Inside an American emergency light (with schematic).
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- เผยแพร่เมื่อ 17 พ.ย. 2018
- This American style LED emergency light was sent by Andy for exploration. It's very neat, I like it. That might be because it's so different from the normal UK versions and has a certain "American appeal" to it.
The design is simple and functional, and the choice of red LEDs means that it should put in a good long service life. Changing the battery pack is easy and the circuitry is simple, so it should last a long time if the transformer runs cool.
The transformer is tapped for 120V and 277V for use with standard supplies or the higher voltage lighting circuits. Make sure you always insulate unused taps on transformers as explained in the video.
The case has no screws and just snaps together which is an interesting approach.
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This also keeps the channel independent of TH-cam's advertising algorithms allowing it to be a bit more dangerous and naughty. - วิทยาศาสตร์และเทคโนโลยี
In the USA, we use 480V 3-phase in a lot of industrial applications (presumably because 120V isn't good for delivering industrial levels of power). 277V happens to be the phase-to-neutral voltage of a 480V three phase. So that's why it's often used for industrial lighting; it doesn't require an extra transformer beyond what's already being used.
Was going to add this myself - most office buildings are 208v 3P 4W, so lighting is typically 120v. Industrial settings for the most part these days are 480v 3P 4W, so 277v makes sense in that case - no extra components needed.
Also more suitable for multi-thousand-foot runs in parking lots and warehouses due to the higher voltage
TailSaber Those are the same reasons most of the world runs on 400V 3P, which gives 230V phase to neutral or on 220V phase to neutral which gives 380V phase to phase. Britain was the odd one with 240V/415V . Unlike the US, none of us bothered with split phase after switching from DC to AC, as proper 3 phase has so many advantages even for household appliances like washing machines, plus it used to be common having small industries and homes mixed in each neighborhood, so would be impractical to use separate grids,
277 V lighting branch circuits can have more fixtures for the given ampacity of the wire. Less voltage drop on long runs (such as parking lots) as well.
We use 480V 3P because of current draw, voltage determine insulation, current determines how big your wire will be, reduce the voltage you can use smaller (cheaper) wire. There are also 575V motors so they can use 600v insulated wire and still have room for boosting voltage to do VD compensation.
277V was popular for fluorescent light fixtures because in the days of magnetic ballasts, you could wire individual fixtures to the three phases of a 480V 3P system, and collectively reduce the effect of the lamps strobing at mains frequency. It not only reduced eye strain, but was a safety enhancement for fluorescent-lit workplaces with machines that could possibly be mistaken for not running due to the strobing of fixtures on a single phase.
A real transformer for longevity and a user replaceable battery. So much better than the replace entire fixture every 5 years disposable stuff.
Yes indeed. This does look reliable.
The Dollar Guy the originals with incandescent bulbs would always melt the fixture from the inside because of the absolute lack of any cooling solution.
Yeah, i'm impressed by the way they did this, i'm actually considering them for replacement with the garbage ones we have here in Europe. Especially the tube ones, ugh.
looks old, they're more chinesium electronics now... although many with old school SLA batteries are around, the battery cost is causing them to be replaced
Not if it's your objective to sell lots and lots of exit signs....
I work in a large industrial plant. (10 acres under roof) We often use this brand of exit signs. New in the box, they come with a second legend plate which can be exchanged for the blank back allowing mounting on the end or top to a wall or ceiling with visibility from both sides. Very versatile. I discovered the live transformer lead issue in a unit which was not working because the unused lead shorted to a metal junction box and dragged the voltage below the working threshold. Having heard arcing in the unit, I was very careful when examining it!
I've also installed these where I work, and all of ours came with the second plate for the back.
That's the type I was talking about in the other comment section, the type with the 277V transformer.
As someone else said here, the 277V tap allows this to be used in installations where there is 480V three phase. (277V from phase to neutral)
480V three phase is fairly common in large industrial or commercial buildings.
I love a well-laid-out circuit board. Someone clearly took some pride in this layout! It reminds me of turret board construction.
PLEASE more morbid stories. I teach electronics to students and nothing helps to emphasize the point of safety more than such stories. And I ran out of stories of me getting zapped because of my stupidity.
I have many.......
1- never trust the guy that says "The breaker is open".
2- If you don't check for errant strands of wire on a terminal row, you will replace said terminal row.
3.-If you try to use a drive that is rated 410-3ph-1g-1n on a power supply that is rated 440 3ph1g, said drive will die gloriously.
4.- Check the new guy's work for a few days and make sure he doe's not put all of the "extra wires" in the bottom of a 480 x 240 x120 volt transformer into ONE LARGE WIRE NUT. It will release a LOT OF MAGIC SMOKE.
Rent a copy of the Martin Sheen movie "The Believers" and show the opening scene. I was a teenager, not afraid of electricity, and since I saw that I've been very wary.
I heard in class of a copper thief stealing the copper bonding from a transformer substation and died on his way out from the brand new electric fence.
Never be one "thing" away from a fatal situation. Always treat the wires as live, even if you know they're dead. That's saved me a couple of times. Once from my own stupidity and once from someone else's mistake. When death is on the line, you want as many safeguards as you can reasonably get.
When I was at school doing a project involving water pumps and a tank, the teacher handed me a "12v" transformer to wire up my damp windscreen washer pumps. The zero had rubbed off. That's the one time I've ever been electrocuted (based on the fact I passed out for a few seconds I'm going with electrocuted!) and I can't say I enjoyed it.
Moral of the story - teachers are assholes :)
We've transitioned in Canada to the green exit signs with the running man looking like he just stole something.
You probably live out west. In Southern Ontario I have NEVER seen a green EXIT sign anywhere.
I think the green ones are required for new installations in Ontario. We have them in parts of the building I work in that were renovated recently.
@@rick_. Haven't seen any yet myself, but I wouldn't be surprised if you were correct.
@@rick_. Ontario requires for new construction and certain renovations. This has been case since 2014. It made all the papers. It was actually sort of interesting as the case made was that international persons or non-english/french speakers would not understand "EXIT"/"SORTIE", but they expected people looking for "EXIT"/"SORTIE" signs to figure out what the green man meant.
They were tested in Detroit for a few years before certification.
Depending on local jurisdiction codes, we also have green EXIT signs in the US. There is some discussion on whether red or green is more visible in a structure fire situation.
Years ago I worked in a 3/4 star hotel as a "maintenance technician", (AKA engineering technician). As I was new to the field, I began as what was referred to as an "Engineer 1" then later on after I had learned more, I was promoted to an "Engineer 2". Ultimately, I was made the "Room Care Tech." (someone who's primary job was to refurbish both guest rooms and conference rooms to tip-top shape by repairing anything maintenance related). So... as I was learning my trade, I learned that in my particular hotel we didn't actually have 220 or 240VAC (the old industry norm.) but rather we had 120 and 208VAC. I was told the reason that many businesses or industrial buildings were converted or otherwise spec'd to 208VAC was the fact that the power grid in the US is becoming so overloaded they were backing the "industrial norm." to 208VAC to lighten the load on the grid. If a business really wanted or needed 220 or 240 they had to pay out the nose for it. During my time there, I found that most things that were designed for 220 or 240 would usually work just fine at 208. I enjoyed that job because I worked with some good people who taught me a lot. I just thought I'd pass that on as some FYI about American power grid voltages. Keep up the great work, Clive!! 🍻
Yes Roger Smith I remember those days real well. I worked for Holiday Inn the same place two times for 6 months each but that was all that I could handle of it from all of the boredom after repairing everything that needed caught up. A boring lonely job that is, especially on the night shift.
It’s amazing how a simple “exit” sign can trigger nostalgia of many American films.
Reminds me of school
You should have a those radioactive tritium glowing exit signs you can buy. Apparently they last for 20 years. Not really electronics but I think it still fits in with your channel well.
In UK do you now have Brexit signs?
Now there's an idea for a project.
@@bigclivedotcom
But the engineer who designs it has to leave and then it goes "Bang"
Backwards electrolytics way under their rated voltage will give you exactly the right amount of time for the boss to arrive before they go bang. I know because I did that experiment.
Ba dum tiss
Without the capacitor on the control transistor's base, the sign would switch to battery power whenever ripples on the input capacitor cause the voltage to drop Vbe below battery voltage instead of only while AC power is severely below spec or out altogether. The base capacitor reduces the circuit's sensitivity to input ripples and low AC input voltage so the sign doesn't waste battery power until it becomes absolutely necessary.
I took one of these apart around five years ago. The unit I had was exactly the same although I never got around to reverse engineer it. Thanks for uploading this video and finally putting my curiosity to bed!
You were inside an exit sign. The paradox are complex... 👍
The best part of these videos is the notepad and schematic .....you must have a stack of notepads filled with scribbles by now Clive
I've always had piles of notepads full of doodles, schematics and software.
bigclivedotcom Hope you’ve made backups 😂
@@bigclivedotcom you should publish those you could sell it and make a few bucks or just give it away free. Either way I'd check it out.
Hey BC, ever hear of the American electronics guy Forrest Mims?
In the 1970's he authored ( by hand including text ) a series of small books that filed the racks at Radio Shack stores titled Getting Started in Electronics and Engineer's Mini-Notebook. There were also articles in various electronics magazines. Great stuff.
I love the way Clive ends the videos. Doesn't reference all the other videos he wants us to watch. No like and subscsribe. No 30 second fade out. Just business.
My first thought when looking at those wires: oversized USB lead
When I saw that 5v on schematic I was thinking "... you can run this off USB?"
Technically speaking it should be an easy conversion. Possibly even a simple plug-on one.
@@bigclivedotcom please do it Clive
Thanks for featuring this Mr Clive. I'd installed several of these and intuitively already knew to expect this. I snip off the red wire leaving only a few inches then pinch electrical tape over the end to leave a square flag. Since it's not a stripped end, this just keeps the wire from butting up against anything. Though, fortunately, since the unit is plastic any wayward installs shouldn't become an epidemic.
Awesome Clive CAD drawings. Keep up the channel enjoy so much.
277v is nothing. In Canada we have a terrifyingly high voltage of 347/600V for our lighting systems. Always fun sniffing out a broken neutral.
Ontario!!! I have designed machines to go into those installs. PITA to be honest!! 330/575/3ph delta is the official designation for 4W and 575/3 for 3W delta. Typically just called a "600v" system. Still its a real pain for equipment designers like myself. Thats where we push off the distribution transformation of voltage onto the customer and supply a normal 120/1 system.
Many years ago I fixed shipboard RADARs for a living. The bridge display units had 600V DC at multiple points and I took shocks to the hands many times. At 600V the arc burns a perfect pin-sized hole into the skin right to the bone. Didn't actually hurt too much and after a day it will close over and then swell up a bit. LOL
Martin Green That is terrifying
@@kraio-sfu as someone who loves to play with pulsed high voltage and also high frequency tesla coils, i can assure you that there is worse. You can get a shock with the skin effect, which will basically cause a really large wide burn without the feeling of getting shocked. the pain comes much later.
@@drkastenbrot - You should probably point out that "skin effect" is not so named because it burns human skin, but is actually the tendency of very high frequency electricity to flow most heavily at the outer edges of the conductor. The higher the frequency, the more the current is pushed outward, to the point that at the frequencies used in RADAR and Tesla coils, you can actually cut out the middle of the conductor (saving copper and weight) without reducing the ability of that wire to carry the current since the wire core wasn't really carrying current anyway. I've never played with Tesla coils, but I have a mental image of super high frequency/voltage flowing through the outer millimeter or so of my flesh without affecting the inner tissues. Yikes.
we have a very similar exit light at work, but it had a few more transistors on it. After reverse engineering it, 2 of the transistors formed an SCR (cross-connected) so that when the device is shipped, the battery is connected, but the LEDs do not light. Once power is applied for the first time, the "SCR" is triggered and the LEDs light, and will continue to light when power is disconnected. Disconnecting the battery will reset the battery "freshness seal"
Right. Our transformers are out in front of your house. 'Round here it's 2 houses to a box.
I think the extra capacitor is to keep the the battery from activating when the ac line crosses zero. There is a smoothing capacitor on the other side of the rectifier diodes, but you can still see the LEDs pulsing a bit when run on AC power.
That's correct!
I'm not sure an exit sign needs to provide "a good long service life", I heard they're on the way out
Baaaaaaed joke!!!
Here in Calgary, the green running man exit is legislated for all new construction, while the old Red Exit are grandfathered until renovations. Red is a little less irritating definitely.
It's a "Western" thing... the US western states like Colorado and California have used international green EXIT signage for decades now, whereas the Eastern states still use red signage.
@threeparots1, here in Ontario the Green Running Man is the new standard. Old buildings keep the traditional red exit signs until reno's or replacement time.
I just noticed a green sign last week at a recently renovated MacDonalds in NS. It looked exactly like the on Clive showed recently.
I'm in Ohio and all of the signs I've bought for the last 5 or so years have come with a green panel you can put in to replace the red one and a switch on the circuit board to switch from the row of red LEDs to a row of green LEDs. I've always left them red because that's what I'm replacing.
@@pingumcping I guess we just like to live dangerously. :)
my apartment building just replace all their old Exit signs with these new LED signs. I grabbed the old ones and scrapped the transformers and circuits. It literally took them 2 hrs just to install one sign! I dont know if maintenance was having trouble installing them, or just milking the job. Thanks for sharing the new ones I didnt really get to see inside these.
I wish I could find one of the old edge-lit Exit signs my grade school had, it had a bronze-ish colored background with red letters, and lacked battery backup. I remember it clearly, mounted on the ceiling above the crawlspace door (where they "discovered" asbestos in 1990, and were surprised to "discover" asbestos there again in 2015).
A hospital near me has one wing that has received only very minor facelift-type renovations since the 1960s (the original building was built in 1913). It has an aluminum-walled boxy Exit lamp with white plastic signs that have "EXIT" emblazoned in black. At the bottom of the aluminum box is a rectangular opening with a light diffuser at the bottom, which probably seemed like a good idea on paper to shine down to the floor, but in reality most likely was of dubious effectiveness.
I have installed a few cases of that very fixture. So much better than the incandescent ones that had 2 sets of lamps. The 120VAC and the 6VDC lamps.The old type used to have gel-cells and
over time the trickle charge would cook the cell. You could get new cells and other parts but it was less hassle just to replace the fixture. We got so much better life out of the LED ones.
How old were the 120V lamps versions?
I have replaced a few old Euro ones (admittedly, the oldest I've seen were 20 years old, so they would be from around 1993) and all the ones I've seen used either 6V bicycle lignbulbs for "standby" and "emergency light" modes (Euro unit must do both tasks : showing the direction of the exit, and also, provide enough light for your to actually see around the room you're in) or 12V car lightbulbs (or 12V lightbulbs for standby and a fluorescent tube for light, and for 'transitionnal" units, orange or green LED for standby and lightbulbs for light before they went all LED).
@@LeSarthois I think they started to die out at about 4 years. Because at the time I was head of facilities maintenance I always had the lighting on my list of things to test. One of the other buildings that I took over after the manager was moved elsewhere I had to do all the emergency lighting.What a mess. I did both pathway and exit signs, The code here is 90 minutes of lighting during a power failure. I even had to replace a central battery type unit that had started to leak from the very large batteries. That was a spendy hunk of hardware and very heavy.
Yes I know that sign very well. I was installing one for a church.... As I was installing it I had an issue with one of the knockouts so I had to get the drill out and as I was drilling it I caught one of the wires. I had to do transformer surgery and I managed to just barely be able to reconnect it and solder it back on and seal it up. And wouldn't you know it of course it was the one wire I needed I believe it was the hot, if only it was the 240v line as our emergency lighting circuit was 120v.
I always wondered about that extra lead I've always capped them but I've seen them not capped.
And in case you're wondering after installing the entire tech booth audio video and finishing the electrical in our new building because the volunteer electrician got to busy, few years later I was told I didn't know anything by the pastor which used to be my youth pastor at one point prior to the church plant. But I digress there's broken people in the world and nobody's perfect but at that point I decided it was time to leave.
I came back 4-5 years later working with a band for an event held there and they did not change pretty much anything except for what I expected to change ... new speakers, I guess it was good enough that the pro sound company that came in couldn't make to many recommendations.
I'd guess the extra cap at the transistor base adds a very small time delay before the LEDs will be switched back from battery to mains. Probably something useful when power comes back and goes a couple of times in quick succession.
Or is used for additional smoothing since main capacitor is not enough. There is a noticeable flicker on camera when on mains.
Designed by a real engineer who wanted a pleasing delay from mains operation to battery, with a soft start on the LEDS.
That would kinda make sense especially when you consider that these things are after all designed to guide an evacuation in most emergency situations ranging from local problems with a single building to severe storms or other disasters that could afflict the entire regional grid with numerous transient faults.
Probably the other way round, to protect the life of the battery... if the first capacitor isn't fast enough while charging to keep the voltage high enough through the whole wave as it discharges through the LEDs before its next charge part of the cycle, the voltage across the +5 to ground rails will spend time at a lower voltage than what the battery's able to kick out, and you'll end up using the battery for smoothing the power to the LEDs, causing them to switch between tiny charge/discharge cycles 120 times a second... with the second capacitor, which will discharge slower than the first as resistance across it's discharge path is much higher, will stop the battery from discharging anytime the +5V rail drops below the battery's voltage, as without those transistors, the battery won't start discharging until the +5V rail drops below the battery's voltage minus the voltage drop across the 33ohm resistor, which you'd hope the first capacitor is at least capable of stopping it dropping that low. The flickering you can see from the LEDs when running from mains is an indicator of how much the battery would be constantly discharging to fill in the flicker without the capacitor keeping the transistors off.
Something about that circuit just seems... cute. In a completely non-disparaging way.
Thanks Andy. I was hoping we'd see one of these.
The white lead is neutral the black is hot where I live in America. This could be deadly if the wrong hot is assumed. 277VAC is a single tap off a 480VAC 3 phase transformer.
Upon I think trying to get through this for the 5th time and falling asleep.
I noticed the LED is on that side of the test button to indicate incoming power and not be affected by the capacitor, although they could've put it on the other side of the button to indicate that the button was working when pressed.
Interesting simple design, although I am partial to the green color signs we do have them as well. usually a different color plastic, I don't know about the lights now that they've gone LED. They used to be just a little 7w( screw in bulbs like nightlights take ( but totally different because those aren't rated for emergency use…).
From my brief visit to the UK I think the exit signs are more classy with their symbols rather than words.
This video reminds me of my dad's efforts as an amateur electrician.
He wanted to install an electrical line in the basement to power his electric organ.
He reversed the live and the ground wires, so that, although the organ worked, if anyone touched a metal part of the organ, he got a shock.
Oh god, thanks now I’m gonna be looking at these everywhere...
I leant from my dad he sadly died last year August last year and. Safety very important
In the US we have a couple different kinds of 3 phase power, 208Y/120V, 480Y/277V, and 120/208/240 high leg Δ, as well as 480Δ (these are the 4 I know, but there are probably more). That is why the transformer has a 277 volt tap on it.
I’ve always been intrigued by the tritium ones. They are hard to come by nowadays in the US.
Nifty gadget! We have a similar design in our local Hospitals (with green lettering rather than red). Ours are designed for 240V operation only though.
I use these in schools. Commercial buildings have available to them 110-120V outlets. a couple of schools I worked in had their lighting at 347V. Also available is 220V for stoves and small fans like roof exhaust fans. We also have schools with 12V networks to operate relays. Finally 550V for motors, large fans and large rooftop AC units. This is in Canada.
I haven't seen an actual mains power transformer for years! Americans are so quaint with their technology.
I like the graphic of the European sign, especially since it makes it easier to understand for those who can't read. However, I feel there's much more simplicity in the visual design of the American sign which also makes it fairly clear. I also think the red is a better color for the purpose.
Your eyes are roughly 20 times more sensitive to green photons as they are to red photons, thus the change.
Also, in the case of fire the green will be seen as a sign rather than possibly confused for a spot of flame.
@@pingumcping never seen them in the US, only European media so didn't know that
IMHO, they should have used blue (or a blue-green) because most colorblindness is green or red. But then again, men are affected more often by it, so it wouldn't surprise me if the agencies don't care.
I'm going to miss the red exit signs though, they always stood out more than the green ones, in my opinion. (and I'm not colorblind) But that might also be due to my interest in engineering and/or design, where green means "good" (I guess you could say though, the exit is a "good" place to go? XD)
@@pingumcping we fucking NUKED Japan! Why the fuck should we have to adopt their signs?
@@pingumcping we use the running man ones in the usa too. in both red and green. it just depends on where you are. places have different fire codes and laws. i know state sovereignty has become hard to understand when you have your eu parliament dictatorship unilaterally handing down laws to you for your own good.
Nice test. Thanks for sharing👍😀
In Canada, many commercial buildings, apartment buildings, etc. are wired on a 120/208 three phase scheme, or on some sort of intermediate voltage such as 277/480 or 347/600. Where intermediate voltages are used (mostly commercial buildings), as many loads as possible are wired on this intermediate voltage, however, transformers are still needed as there are still a few 120 volt loads to be supplied.
Red lights are to help navigate in darkness. The light doesn't effect the dilation of your pupils so if you were to go into a hallway that is pitch black, you can see the signs clearly and still see surrounding area so you don't trip.
IMHO this fixture is a bit dangerous with the loose wires. A lot of multi-voltage equipment I've seen, they don't strip the wires and they dip the ends in a sealant so there is no exposed conductor. MUCH safer. Make you strip your own wires!
Here in US most new construction uses the green exit signs as well. I have seen both but I'm not sure of the code requirements, red may simply be older or it may be allowed under specific circumstances.
OK article covering exit sign colors in USA. more governmental tomfoolery involvement for sure..
blog.1000bulbs.com/home/exit-sign-guide
The US light is just like the display screens on German airports. They light up once they're connected, no matter whether the airport is online or not. Thus, this summer, they found out that at the BER airport of desaster, all the screens will have to be replaced before the airport is even in use, just because they've reached their end of life displaying nothing at all. I wish I knew where the trash bin for those "old" new screens is sitting...
Two transistors - considering the point of the transistors is only to reduce the resistance in the circuit (the 33ohm resistor plus the two diodes) that the battery current has to go through to light the LEDs (after all, if you remove those transistors, the battery will still light the LEDs, but dimly) that might be a clue that it's to reduce the resistance further... that the chosen transistors have too high a voltage drop across, but this value is halved by putting two in parallel, allowing the battery to light the LEDs brighter, and warm the transistor less... IOW, it's a cost issue or something, a single transistor at the right spec may cost more than two cheaper transistors that will reach the spec by team effort.
White is netural. We still call it 'neutral' over here.
Black is hot. For 120V.
That Orange wire should be Red? Either way, it's 277V, which is one leg of our 277/480 three-phase service.
It's not that 277V is better for ballasts, it's that, if you've got a really big building and lots of lights, you can jam a lot more lights on a 20-amp 277V circuit than a 20-amp 120V circuit. Also, the service to such buildings is quite often 277Y480 (480V WYE, 277V per leg) with another transformer in the building to get 120/208 wherever it's needed. Running all of your lights straight off 277V gives you that much less demand on your transformer.
My office is all wired this way -- all of our lights are 277V, HVAC is 277/480, the exit signs in the hallways are 277V.
That story reminds me why I always cap off unused wires, even if I know for sure it is dead. You never know what can happen.
I like it. Elegant in its simplicity. Even the PCB looks to be designed to use minimal etching. No switchmode PSU rubbish either
Chances are the transformer costs less. An isolated switcher still needs a transformer.
There are several versions. This is your classic red. You have the classic green as well which is identical except for green plastic and green LEDs. You also have the tritium types and the phosphorescent types that are glow in the dark material and are charged by the existing room lights.
As usual, the US is weird and varies state by state. The feds only require that it says "EXIT" in a certain size - color is left to states or even municipalities to regulate. Some are green, some are red - I think one is even orange. Some places let you use photoluminescent signs, which obviously do not need testing. Another "as usual", NYC is weird (for the US) and is switching to the green running man (not on the lit signs, but on fire doors).
NYC is unlike most US cities, in that it is composed of five counties. In some of those counties, English is NOT the language spoken in some 50% of homes. About 40 other languages are in use, about 6-8 are used at the polls and in other places. NYC puts an unusual emphasis on not using English but using symbols instead, so there is less confusion for the many folks who speak no known language.
Its a good idea to cover off every wire that is not in use always
I think the floating lines is a bit of a ridiculous idea. Surely they could have had some binding posts or something and if you want to wire up to either of the windings you can, without a hazardous thing flapping around.
@@BenHelweg Or both wires could have come capped right out of the box, letting the user uncap whichever one is going to be used.
Its weird how he left the wire there, he should have cut and taped it. Was he certified to do the job?
I've got some old metal-cased exit signs w/ glass letters & incandescent bulbs, inside. One is double-sided; would be ceiling-mounted in the middle of a corridor/hallway.
I remember when UK exit signs were like that, in fact I was working at a village hall the other week that still had them. No euro signs for them! Far clearer and unambiguous.
Village Hall hadn't updated its signage; immediately makes me wonder if there are any other changes in safety they had missed out on.
@@gleggett3817 its ok, it was in a village where they all spoke english
Here in the US, most homes use 120V/60Hz service, except where there is an electric stove or dryer or other large electric appliance or heating system that requires 240V. Yes it's split 240V, with 120V on one side, 120V on the other with neutral in the middle.
So things like stoves, the 240V runs the burners and heating elements in the oven, the 120V side runs the electronics where present. Dryers, the timer sees 240V at the on position for timers, be it mechanical or electronic but itself runs off of 120V and at the heater elements. The heater elements require the full 240V, with one half coming from the motor start switch, the other half is fed by a series of thermostats, one being the high limit switch, the other the actual thermostat, together they make up the entire 240V circuit.
I know first hand as last summer, I lost heat in my dryer last spring, and with some assistance of an appliance repair forum, I figured it out and it was the motor start switch and it's an easy fix. The switch unscrews from the motor itself and is easily disassembled and the contacts cleaned, reassemble and that's that. I got heat again.
Anyway, while testing, I was getting more like 121V per side of the 240, or in this case, 242V as I was literally within sight of the transformer that serves my house out in the back alley. I'm not the only one on that transformer however but the proximity to it determines whether your service is 120 or a touch higher.
Also, I think building codes have standardized of recent years as it depended on where you lived and what jurisdiction you were in because you may not have had much in the way of building codes but I believe that's all changed to simplify the building codes in the US, and that I believe also applies to electrical codes as well. This was done to help those in those trades/fields to be able to move from one area of the country to another and the code is now codified as at one point, there were something like 6 or 7 jurisdictions and they were all different, so when the standards were codified to one basic set of standards, they then took in some of the variables from say Florida where hurricanes are prevalent to areas of the Midwest where tornadoes exist to the NE for the Nor'easters that hit most years putting on feet of snow to the west where wildfires in the SW and earthquakes for much of the west coast are now part of the code itself. Even though it's not a federal, nor technically national code, it is adopted nationally and all cities, towns etc must do their best to adhere to these codes or they ARE held liable for any injuries or deaths due to inadequate building and electrical and plumbing standards as I believe it's all the same for building and water as well.
So things like older standards are grandfathered in until a major renovation takes place, such as remodeling the kitchen in an older home that predated GFCI outlets, once renovated, it MUST have them as part of the modern code being just one example.
I'm not in the trade, but did read up extensively on this 3 years ago or so.
7:22 It's very commendable that you don't see the difference between black and white, but only when it comes to people, not when it comes to wires.
I disassembled one of these (in the US) in the 1980's. Back then they had two sets of incandescent bulbs inside - a pair of 120 volt tubes for normal use, and a pair of 12 volt automotive bulbs that had to be connected to an emergency lighting circuit.
Wouldn't normally think that its essentially an auto-transformer. Definitely worth noting...
Those little 120/277V transformers are marvelous for building Cockroft-Walton ionizers.
I've toyed with whether they could be used like that. Theoretically a small secondary load like an indicator LED would help with primary coupling too.
I was about to ask you about this, glad I just searched first. I was recently thinking of trying to tear down the little pcb to use the boost circuit to drive 5V IC's from the 1.2v NiCD cell that comes with the standard led exits I see. It seems clean enough at around 5.7V with a little extra smoothing and will take 12v input to recharge slowly.
infact, there is a green color option and a combo (lamp heads attached to the unit)
EDIT: here in the US, style varies alot. my favorite style is black body with cast aluminum front and green text.
Awwww, I was hoping you'd hook up the black wire.
New Zealand like Canada has officially moved from the green "EXIT" signs to the running man. Older installations are grandfathered in but cannot be used in new installations.
In America we have 3 phase, 2 phase and high voltage I can't tell you much about the three phase right now, but I know that the two phase is in everybody's houses and operates in 120 volts AC and high power is 220 for things like clothes dryers and stoves
Wikipedia's definition for 3 phase:
Three-phase electric power is a common method of alternating current electric powergeneration, transmission, and distribution.[1] It is a type of polyphase system and is the most common method used by electrical gridsworldwide to transfer power. It is also used to power large motors and other heavy loads.
A three-wire three-phase circuit is usually more economical than an equivalent two-wire single-phase circuit at the same line to ground voltage because it uses less conductor material to transmit a given amount of electrical power.[2] Polyphase power systems were independently invented by Galileo Ferraris, Mikhail Dolivo-Dobrovolsky, Jonas Wenström, John Hopkinson and Nikola Teslain the late 1880s.
Etham Cohoon What you call "two phase" is actually "split phase". Actual two phase is an obsolete system used in the early 20th century. It consisted of two single phase circuits 90 degrees out of phase with each other.
I frequently work on 24V transformers with 120/208/240/480v inputs. We use the 208v tap.
It does not feel good when you brush that 480v terminal with the back of your hand.
You can run a lot more lights per circuit at 277 than at 120v. More lights per switch without having to use a contactor for multiple circuits. good for large offices or factories.
In most cases these exit lights are on a dedicated circuit breaker, not only to insure they continue to get power should a device plugged in somewhere else cause a breaker to trip, but also to do extended battery testing/repair simply by disconnecting power to the signs exclusively. Not sure if that is required in electrical codes, but it is widely considered a "good practice."
You can run even more lights on a 347V circuit ;)
It depends where you are, Ive only ever seen the exit signs on their own dedicated circuit once or twice, usually we have always just wired them to the nearest lighting circuit.
@@dashcamandy2242 I just meant that is why most commercial and industrial building have a 277v system. So they can run more lights(not exit lights) per switch and circuit. It's a lot easier to have 5 switches with each doing 50 lights, than 20 switches with each doing 10 lights
The older lead acid ones of these always had ballooned batteries in them lol
iamdarkyoshi LOL, that’s how you know when to replace the battery when the cover is pouched out!
I miss the nostalgia of seeing the backside of the older signs with two bulb-shaped, brown-colored, heat-warped, spots from the old "test tube" bulbs inside.
They were continuously overcharged. Doomed
But lead is supposed to like being continually charged. They're just only good for five or ten discharge cycles (power outages).
In the US, certain areas can dictate what color the exit lighting is. For example, in one county in the State of Colorado, green is the required color. Never opened one up to see what color the LEDs are, but the plastic is green.
Oh Clive, you didn't just say that we in the US get 240 by going across two phases, did you? We have single phase power in residences in the US. It is 240V, single phase, center tapped with two 120V legs. You get 120V from each of the two hots to neutral (yes, the white is neutral, not "common".), and 240V across the two hots. It is single phase. Not two phase.
Many industrial buildings in the US run the lighting off the 3 phase power. This is the reason for the slightly odd optional voltage input.
Reason the back also snaps off is that double sided versions are available. It is cheaper to make a blank side than a new mold for 1 side and box
I remember back in the late seventies, when I was completing my electricians' "apprenticeship", these signs becoming standardised in colour and form.
I think this was due to EC conformity (but I may not be entirely correct here).
We (as students), were told that the signs were now to all be green, due to each language having a different word for: "EXIT".
And green means *"GO"* as opposed to red, which universally, means: *"STOP"* (At least as far as I am aware).
This made total sense to me then, as it still does now, and I cannot understand why this red colour, (or should that be color?), continues to predominate in American emergency exit signs today.
In fact, the standardised European emergency exit sign no longer employs the word "EXIT" but features a graphic of a running biped in a particular direction accompanied by an arrow should the direction of the running figure prove a little distracting for those of a thoughtful and contemplative nature.
Outside of traffic applications the use of traffic colors in other applications is usually a code for severity rather than permissiveness. In that context Green often meant OK/normal while Red indicates Emergency and was considered conspicuous and attention grabbing. Though several states in the US do recommend or require Green Exit signs rather than Red, but the legend on it is still the word EXIT rather than the ISO pictogram
I've had these open before. I've never found a logical use for 277v. These signs are really only used where 110 is being used. It's also just for LED'S. I've never seen one of these in such good condition. All the ones I've seen have been pretty beat up.
Shinigami Lee it's not 240 it's 277, and many buildings use 277 for lighting circuits.
It's a misnomer or misunderstanding that US residential power has 230V across two "phases", we have transformers with one distribution phase and two 115V secondary windings, one turning in the opposite direction, to create two "poles".
Relative to GND the two sides of a North American power installation are indeed 180 degrees out of phase, but it's really just one 220V phase with a center tap.
Technically you could call it "two phase" but usually it is referred to as "center tapped," or in the case of being connected to circuit breakers and such, "two pole." (Two "hot"/live wires)
The reason why "two phase" is not correct is, there were older power distribution systems that used two phase, *90* degrees apart, thus making it easy to run motors. Of course, if the loads are not balanced, the phasing will be off, so the circuit won't work well (possibly even overheating the motor!). So, it wasn't very popular.
I prefer the term "split phase".
trickster721 Technically, it's called "split phase".
There is no such thing as 110 volts or 115 volts in North America. Standard line voltage is 120/240 single phase or 120/208Y three phase. Commercial buildings are often fed with 277/480Y three phase, in which case the 277 volts is often used for longer lighting runs with less copper, while one or more transformers step it down to 120/208 for standard loads.
You will NEVER see 110, 115, 220, or 230 volt mains in the United States.
Nice reverse eng. The cap on the base of the transistors might be just to hold them off after power fail for a short time - though I still can't see a good reason to do that from your cct. I like the way you had a stab at what wavelength the leds are Clive - very good ! ( I just checked, and yeah, 640nm looks a good guess - very orange-y)
A very neat and clever design, double pnp transistors give less vdrop when on, i would have thought :-D
thats a bit old. In Iowa USA, we have off the ceilings ones similar to your icon someone made shining Green LED's thru transparent plastic that light up the Exit sign. all green here..
I really like it when you not only tell us but show us the differences from the UK and USA. I've heard 2 reasons why North America uses 110v volt 1 is the Edison and Tesla rival and amount of copper needed and number of substations to run DC the other reason was recent from AvE he said this major copper mine was producing so much copper they pushed to run 110v( SMALLER VOLTAGE THICKER wire) but if that was the case why didn't we go with DC. I know Edison zapped the baby elephant in public to show teslas electricity was bad. Edison was a dark dude.
No complaints here about only having 110. Been shocked more times than I care to admit, one being grabbing a metal pull chain on a light fitting that had become live, while I was bare-foot. Interesting situation to actually let go. Had to wait for the zero crossing before I could open my hand.
Also the choice to stay away from DC was simple: Voltage drop and transformers. That was the major downfall of DC was that it could not be stepped up or down. Even with thick transmission lines it was still an issue. With AC voltage drop is handled nowadays by multi-tap transformers at substations. As the load changes, different taps are selected to handle under and overvoltages.
you want high voltages for long range transports and high power applications. You don't want that for local installations. Transformers are easy and cheap. Basically the only way back in the day to change DC voltages was a motor/generator pair.
@@FreeOfFantasy
As ukezi said AC is much more efficient at moving high voltage/high amperage at distance. DC loses much more power beyond about 100 ft./30m.
@@dr666demento beyond 300km HVDC transmission is more efficient.
Clive, do you suppose that capacitor is to prevent flicker when there's a problem with loose power line connections at their transformers outside on the pole during a storm?
I install many of these units. They are much better than the old lead acid versions but they are light weight and flimsy so getting them to hang level is a pain. Often when I open one up the helper monkeys installed and doesn't work.... They didn't plug in the battery and they tend to leave the 277 wire hanging or if lucky they cut off the bare wire part. The emergency light units now are a royal pain to wire as there is no room for the wire and you are wiring it with solid core wire... We really should be looking into running 14ga for emergency lights to make the installers happy.... Or them design a better wiring connection on the light.
It's 40 years since I was involved with those things in the UK, but most designs of exit sign would also throw downward illumination to save having to fit an emergency light as well as the sign. Upside: lower cost. Downsides: if the sign fails you've also lost illumination along the exit route and the manufacturer sells fewer items.
In Colorado in 2005 I was surprised to see the green exits signs at floor level in hallways and corridors. This makes them visible even under a smoke cloud (where people would be crawling) and also provides some areal illumination.
In the USA, most homes have split phase, so it creates some problems when setting up the power distribution panel (breaker)
so we have to hot legs, a neutral and a ground.
Watched all the way to the end and you didn't tell us what the three diodes in the centre of the board were for... I want my money back!! :-D
that story was a very good cautionary tale.
Something else neat about red lights is that when it's dark and you look at them it doesn't affect your night vision
That is such a sad story. It's worth reminding people though wearing gloves helps a lot. It's saved my life at least once. Plus AC detectors are fairly cheap. You don't have to wear gloves all the time but holy fuck if people are saying they are being shocked proceed with caution.
I've never understood why exit signs in the US are red. The color red has a negative connotation which seems like the exact opposite of what you would want for something that is supposed to lead you to safety. And in the case of a fire, the sign wouldn't stand out near as much against the flames as a green sign.
Tyler Kelley Perhaps the reason exit signs are gradually being changed to green, with the running man on them.
Well, it make sense in the context that other fire-related equipment is red.
I don't think they'll make green fire extinguisher since green "extinguishers" already exist (they are portable showers to be used for cleaning chemicals from people's faces and body).
I was thinking that the probable reason for the same fittings for the front and back panels of the unit was so that a ceiling-mounted double-sided sign pointing to a side exit from a corridor could be made from the same components, by putting a front panel on both front and back of the unit.
In terms of safety, I was wondering why the live wires (black and orange) didn't come already insulated in some way, with a system where the insulation of the required wire could be removed easily (but not inadvertently) when connecting it up. It would then be much more difficult to leave the unused wire uninsulated.
As a Canadian I haven't installed anything but the green running man in years. I don't think these meet building code.
As an English ex-pat who was moved to Ontario Canada when I was almost 8 years old, I grew up with American-style red EXIT signs. In 2005 I worked a 9-month contract in Denver Colorado, and was really surprised to find that ALL the EXIT signage was international green in colour. What really caught my attention though (and maybe this is normal in UK/Europe too but it's not in Canada) is that the signs are mounted at floor level in hallways and corridors. This is so they remain visible if you need to find your way out under a hanging smoke cloud.
I don't think it's normal in Europe. I replaced a few units (and kept a few for myself , heh) and they are always (in France) at "over the door" level. there is a maximum distance for them to be set up (no more than 25 meters between two units if I remember right) but I never heard nor seen a requirement for being visible at floor level.
I remember reading about international versions, and European ones are either outputting more light or working longer, I don't remember which. Supposedly European emergency lights must work at least one hour. (I got old, lead based models with a fluorescent light and it's about that; LED based ones seems to last more, almost 2 hours).
On the technical side, Euro ones connect on 230 volts, and on a 12Volt line for testing and/or possibly centralized/extra 12V independant power supply.
That light color is very close to Portland orange (the color seen on the 'stop' hand on a crosswalk here in the US). Then again, could be the yellowing of my screen. Either way...
Great Shot: Exit” Sign Clive✍️✌️😃
"I need to be careful because this is live" *holds partially uninsulated live wire in bare hand*
That looks like the Lithuania emergency exit light. They come in green and red and are usually pretty cool lights. I've installed many of those over the years on both 120 volt and 277 volt.
Looks like autocorrect turned your "Lithonia" into "Lithuania" :)
@@fillg lol... Silly Autocorect strikes again!
You think the base of that transistor is biased at about 3 volts with the voltage divider (820 and 560 ohms) which forms a shunt regulator holding the battery at 3.6 volts (based on 5 Volts in??)? When 5 Volts goes away the base is at zero and the transistor turns on.
Hmmm, the led's on the sign only started to flicker when the power was connected, is there a way to stop flicker with stuff connected to mains?
Tox Laximus Maybe don't use 60Hz equipment on 50hz with low voltage? You won't drain the filter cap so easily.
Strange how the lights only started flickering once it was connected to main power
Thats AC vs DC for you
And a device designed for 60Hz on 50Hz...