I started many years ago just as you. Worked for a design engineer building process control instrumentation. We calculated the length of wire we use in those nema rated Hoffman enclosures. I think we estimated the amount or length of wire would span the earth a couple hundred times. Those were the days when there was a ton of manufacturing here in this country. Not so any more.
In the US, the line voltage is 240 (or 208) volts between the 2 hot lines. We center tap the secondary of the pole transformer to get 120 volts. So, we get 120 volts between one of the poles and the center of the secondary winding. Because the center tap will always be zero volts when each of the poles are at their maximum voltage, it will never be "hot". GFM
@@DasAntiNaziBroetchen Yes gladly, but there are so much and I find it maybe a bit much to comment on every detail on the whole video. So could you please point out what parts I should elaborate on? :-)
Actually switched mode adapters such as shown do usually have a connection from input to output in the form of a class Y capacitor. Its purpose is to act as a high pass filter and shunt the high frequency switching noise that is capacitively coupled from the transformer primary into the secondary back around to the input side before the switching circuit effectively eliminating it. Unfortunately it also has the side effect of sometimes causing an AC or pulsating DC phantom voltage on the output.
My father, just turned 80. And he is giving me a lot of his old tools. He gave me an old 1950's ShopCraft drill. It's a all metal case. Still works great! I need to replace the cord, and make sure the case is grounded on a three prong plug. They just don't make tools/things to last this long today. Such a shame...
so the only "earth ground" is at the service panel... but the ground part of the outlet does not run to earth ground it runs to service panel and hits neutral correct? if that is the case, then all outlets are considered to have floating grounds if the ground of the outlet is not connected to earth ground? Great explanation and video! ( im just trying to confirm if what i think im hearing is accurate. cheers!
I have two audio appliances which are two prong ,floating ground ,and to get rid of the interference I am getting I have been told to run an independent ground wire from the appliance to the earth outlet on the wall or to an independent copper ground rod(which the house already has one) and that should cure the issue IS THAT advice CORRECT AND SAFE? thank you I understood your video but didn't know the earth went back to neutral I thought just to the earth (ground rod)
Thanks for this video, very well explained. However, I have a dumb question- Why do some chargers and power supplies have 3 prongs even if they are completely plastic? I don't see why it would be needed since you can't get a shock through plastic. Thanks!
LOL thanks. I think I may have an explanation now that I think about it. Maybe it's grounded so the end that plugs into the device can't become live if something shorts out?
Ok my battery powered inverter has a floating ground and will not charge my electric car. What is the best way to have a ground for this type of application? I have seen people use a jumper wire connecting neutral and ground together. I'm not so sure how safe that is. Can you suggest a safer way? Thanks.
I don't think the ground is the problem. Many times inverters do not produce a clean enough sine wave (even the ones that say they do) that is acceptable to the charger. GFM
Thanks a whole lot. You did a fantastic job explaining the concept of a floating ground. Is there any way you would be able to explain how my multimeter reads 110v on the load side of an open ssr as it pertains to a floating ground? I'm so lost.
You need to understand that An SSR is an electronic device. It is not just open as in a mechanical relay. There will always be some bleed thru. Voltage is not power without amperage. GFM
Great video.. Do you know how to correct my generator open ground, so that I can use on my 5th wheel? The safety on the trailer will not accept the power from my generator. Thank you
Get a 3 prong plug. It'll be a dummy plug used for nothing but providing a grounded neutral. Make a short jumper from the ground terminal to the neutral terminal. Do not attached anything else to that plug - Close up plug and insert in any of the receptacles on the front of the generator - you now have a generator that will work just fine with a furnace or some trailers that are wired for grounded neutrals. Takes less than 5 minutes- problem solved
Question..........I live in a double wide Mobil home, I have a large main panel on a pole 20 foot away from my home , I think the neutral from the power company is connected inside the panel to ground, are you saying that when the power comes over to the home and into the main panel in the house, that the neutral should not be connected with the ground bar, if so , should there be a separate grounding stake to serve the ground from the panel in the home, and not connected to neutral.
RJParker is wrong on this one. Checkout 550.11(A) & 550.16 of the NEC. DO NOT connect the neutral and ground together at the panel inside the structure. Any ground rod you may install at the structure should be connected to the ground bar, not the neutral. The chassis of the mobile home should be connected to the ground bar. GFM
I stand corrected. GFM is correct that only the first panel should have the neutral and ground bars connected. I knew that but missed the fact there was an outside panel first.
Thanks everyone, So after further review, this is what I found, At the main box on outside pole (main panel), the neutral and ground are tied together with a bar. There are 4 cables coming to the inside box, 1. Li / L2 / Neutral / Ground. The ground ties inside ground bar sub panel inside) to main panel ground in main panel on pole. there is also a ground wire from inside panel to trailer frame. The ground bar and the neutral bar are not tied together on the inside sub panel. I installed new cables from the outside box to the inside box 2 years ago, and basically redid what was done before, but with all new cables, and put them in Sch 80. Should the ground wire be wired between the Main and the sub panel ?
It sounds like the 2 prong transformer power supplies are safer than a 3 prong device like the tools since they isolate you from the AC mains voltage, is that right? And do you have a link to the playlist you mentioned at the end about the electrical system in the US? I'd love to check it out, thanks
My take on a floating ground can be electronics that have a logic ground but that logic ground is not tied to the panel ground by design. However interconnected devices often will connect to each others floating ground. In a similiar fashion hvac control power is often floating on the common/ground side. It is possible to have a floating ground in an electrical panel because of a bad connection in the panel. This situation can sometimes burn out appliances especially when other items are incorrectly grounded at the appliance, including a previously acceptable neutral tied to equipment ground on three wire dryers and ranges. Floating neutrals are worse.
grayfurnaceman ...im getting the following readings on my digital multimeter ....120v from hot to neutral.... 70 v from hot to ground and lastlt 12v from neutral to ground on every receptacle in my dining room, what is the problem???
Or some weird leakage to ground that shouldn't be there. If the checking connections don't fix it: try flicking breakers on other branch circuits to see if the problem goes away.
Hey man, great stuff, I have an issue with my DJ mixer, i get small electric shocks when touching the metal screws and surface and a small tingle in my hands, now the back of the mixer output (AC) only has a 2 pin outlet (no ground) but routes into the main socket with a standard 3 pin UK plug (with ground), going by the manuals of the mixer i have it shows it has 3 pin output, but I have 2.. will this mean I need to go and have a ground put in the mixer? Or is it just a short somewhere, just asking your advice before I visit my local electronics store. Thanks
Can i connect the neutral (white wire) coming from the electrical panel to the neutral and ground (white and green) of the furnace if i do not have a ground coming from the panel?
If I understand your question correctly that would be called boot legging and is very dangerous!!! You should never connect the ground to the common, or neutral on an outlet. A wall outlet tester will show you have it hooked up correctly but if you use a fluke it will show that you have 120 volts going from neutral to ground when it should read 0-1 volts. Hope this helped.
3 phase electric utilizes ground to run power back to panel, also single phase will run fine with hot and ground without neutral until the GFCI or AFCI comes into play
My generator has a floating ground. The frame is connected to the ground, but is not bonded to the neutral. Your 2 prong plug on the jig saw is connected to the hot and neutral only. There is no ground to float, because it is not connected to ground.
@@grayfurnaceman - You're wrong and putting misinformation out there. floating ground means its not bonded to neutral. The actual earth doesnt absorb anything. Its not some magical place that current goes. The earth is actually a conductor. If you send current to the earth then the earth will be live. The only way to stop current is cut the source.
👍, I just doubt that ground is connected to neutral in panel. What you need is ELCB to disconnect the electrical supply when the phase is short to ground. ELCB: Earth Leakage Circuit Breaker.
My 1970 model pop up toaster has no safety ground connection. Hot and neutral conductor only. This is a floating ground, because it has no ground fault connection. Conversely we know inside the main panel the Neutral and the safety ground are BONDED together. Confusing, seem to be counter to one another?
First, throw away that toaster. The separation of neutral and ground at sub panels and appliances is necessary to keep the appliance from operating with an open neutral. GFM
1:07 "... things you don't want ..." Would it be correct to say: In DC, ground IS the place all the electricity is trying to get to, and while it's trying to get there we put it to work. In AC, ground ISN'T the place all the electricity is trying to get to -- it's the place we send energy which isn't part of the AC push-pull action."
There is no ground in DC. In automotive uses, we may call it "ground" but it is just the second wire of the circuit. We use the chassis of the vehicle as one of the wires. Not always true in newer cars, as they use 2 wires in the circuit. In AC, ground is not necessary for the circuit but we do, as you say, use it to dissipate surges and spikes. GFM
Surge protection strips won't work as effectively, especially important for TVs and computers. Most older houses with two wire outlets are dangerous around wet locations. The safest thing to do on two wire systems is to install GFCIs at any location like baths and kitchens where severe shocks could occur.
Great thanks. I agree on the GFCIs particularly in the kitchen and bath. It was somewhat of a smartarse question I know. I have learned a lot from your videos, keep 'em coming. I have tried to explain this chassis ground concept to a lot of people that see my 2 wire receptacles and I usually get a blank stare and a "uh ughhh uhh that's not safe" as response. Even people who should know better.
all electrical potential returns back to generator sub station via ground earth . Out side substations power plant generators there are large ground rod arrays buried under soil to neutral ground etc. Many are unaware of this.In wye star three phase industrial power systems (such as where power is generated at plant) the center tap is neutral to ground ( earth) and not used in Delta. Three phase primary power line transformers and sub stations all have earth ground which all power generated returns potential via ground. That is why you only see three wires on primary pole in street all hot between each phase in three phase commercial services and ground( earth neutral) for single phase house service. . No neutral between poles because the earth is used for such and pole transformer s usually have a neutral tap to earth.Study motor controls and Delta wye three phase schematic and find where center tap of wye goes....NEC has these diagrams. Nice show Thanks.
I hear a lot of UK commenters say this on various American electrical instructional videos. IMO, you Brits are overly paranoid and always have been when it comes to electrical code. You put fuses in 3 prong wires when such a thing is wholly unnecessary. If it were necessary our board at the NEC would have mandated it long ago. I mean this is America, we have an entire industry of lawyers looking to sue the first time little Johnny gets shocked by an unsafe device. If our plugs were that dangerous I guarantee any such company producing them would have been sued out of existence long ago. You also do not allow any outlets or light switches in bathrooms which I think is insane. To my understanding all bathroom lights must be pull chain (correct me if I am wrong). In America we allow light switches on the wall in bathrooms and I have never heard of someone being seriously injured or killed from a light switch. Electrical outlets, yes, but not light switches (all outlets in bathrooms have to be GFCI protected here nowadyas because in the old days people were killed by hair dryers making contact with water). (
In relation to Automotive electronics the term floating ground is related to some sensor grounds . The sensor grounds are usually on certain vehicles floating meaning means the ground is actually positive with a few hundred milivolts . Like Oxygen sensors , if you use an Oscilloscope on one and ground the scope to battery ground you'll see that it floats about .3V above what you would expect to see ( .1-.8V) . If you probe the sensor ground then you'll see it switching is reference to the 0V line being low reference . The do this to help reduce noise on sensors
The ground should be bonded at the panel and there should be a ground to the waterline or preferably a driven ground rod. A ungrounded tool is dangerous. this term floating ground is dangerous because when you use it, it is misleading the unaware. The fix is simple. Change the cord and drill and tap the metal screw the ground from the new cord to the tool.
You seem to be at odds with appliance manufacturers and the NEC. Computer power supplies, phone chargers and electric drills are just a few. Where would you drill and tap a phone charger to provide a chassis ground? GFM
Exactly right, which is why if you have a generator for your home, you really should do what your manual suggests, which is hook up an appropriately-sized ground wire. Otherwise, the frame of the generator could become energized and kill you. Lifelong electrician and 30 year electrical inspector.
I'm an almost retired electrical engineer. Understanding how electric works can be confusing. You did a good job explaining.
Thanks for the support.
GFM
I started many years ago just as you. Worked for a design engineer building process control instrumentation. We calculated the length of wire we use in those nema rated Hoffman enclosures. I think we estimated the amount or length of wire would span the earth a couple hundred times. Those were the days when there was a ton of manufacturing here in this country. Not so any more.
Great video!! Great Audio! Great lighting! I also liked the way you explained everything! Thank You!!
Welcome
GFM
very educative .Thank you regards
Good Job! Way to relate the topic of a floating ground to everyday electronics. ⭐
For me electricity is not an easy topic to comprehend. I appreciate your explanation of the ''floating ground'', thank you GFM!
Welcome
GFM
Nice explanation! Thank you!
Great explanation. Thank you.
Welcome
GFM
Very very helpful!!!! Thank you Sir!!!!!!!! 👍😄
Welcome
GFM
Thank you.
good video. well said.
4:05 What does "hot" and "neutral" mean in AC, where the energy goes to and fro equally on both wires?
In the US, the line voltage is 240 (or 208) volts between the 2 hot lines.
We center tap the secondary of the pole transformer to get 120 volts. So, we get 120 volts between one of the poles and the center of the secondary winding.
Because the center tap will always be zero volts when each of the poles are at their maximum voltage, it will never be "hot".
GFM
@@grayfurnaceman But AC outlets can have just two conductors. Aren't they both hot?
@@johnaweiss A 120 volt outlet has a hot and a neutral. Neutral has a 0 voltage potential.
GFM
@@grayfurnaceman Wow, i'm very surprised.
Great video, it's amazing how different the systems are! In Denmark would 90% of what you say, be wrong:-)
Can you elaborate?
@@DasAntiNaziBroetchen Yes gladly, but there are so much and I find it maybe a bit much to comment on every detail on the whole video. So could you please point out what parts I should elaborate on? :-)
makes perfect sense thank you
Actually switched mode adapters such as shown do usually have a connection from input to output in the form of a class Y capacitor. Its purpose is to act as a high pass filter and shunt the high frequency switching noise that is capacitively coupled from the transformer primary into the secondary back around to the input side before the switching circuit effectively eliminating it. Unfortunately it also has the side effect of sometimes causing an AC or pulsating DC phantom voltage on the output.
thanks for clarifying this ...
Welcome
GFM
My father, just turned 80. And he is giving me a lot of his old tools. He gave me an old 1950's ShopCraft drill. It's a all metal case. Still works great! I need to replace the cord, and make sure the case is grounded on a three prong plug. They just don't make tools/things to last this long today. Such a shame...
Try a De walt 18v cordless. 15 years of hard use and still going strong.
GFM
so the only "earth ground" is at the service panel... but the ground part of the outlet does not run to earth ground it runs to service panel and hits neutral correct?
if that is the case, then all outlets are considered to have floating grounds if the ground of the outlet is not connected to earth ground?
Great explanation and video! ( im just trying to confirm if what i think im hearing is accurate.
cheers!
my HP has the ground from plug to the box you were showing, then just the 2 wires from there to the laptop.
It does not have a floating ground.
GFM
I have two audio appliances which are two prong ,floating ground ,and to get rid of the interference I am getting I have been told to run an independent ground wire from the appliance to the earth outlet on the wall or to an independent copper ground rod(which the house already has one) and that should cure the issue IS THAT advice CORRECT AND SAFE? thank you I understood your video but didn't know the earth went back to neutral I thought just to the earth (ground rod)
It is safe. A separate earth ground is best.
GFM
Thanks
Thanks GFM.
Welcome
GFM
Thanks for this video, very well explained. However, I have a dumb question- Why do some chargers and power supplies have 3 prongs even if they are completely plastic? I don't see why it would be needed since you can't get a shock through plastic. Thanks!
I have a dumb answer. I have no idea.
GFM
LOL thanks. I think I may have an explanation now that I think about it. Maybe it's grounded so the end that plugs into the device can't become live if something shorts out?
Ok my battery powered inverter has a floating ground and will not charge my electric car. What is the best way to have a ground for this type of application? I have seen people use a jumper wire connecting neutral and ground together. I'm not so sure how safe that is. Can you suggest a safer way? Thanks.
I don't think the ground is the problem. Many times inverters do not produce a clean enough sine wave (even the ones that say they do) that is acceptable to the charger.
GFM
Thanks a whole lot. You did a fantastic job explaining the concept of a floating ground. Is there any way you would be able to explain how my multimeter reads 110v on the load side of an open ssr as it pertains to a floating ground? I'm so lost.
You need to understand that An SSR is an electronic device. It is not just open as in a mechanical relay. There will always be some bleed thru. Voltage is not power without amperage.
GFM
Good explanation gfm thanks
Welcome
GFM
Great video.. Do you know how to correct my generator open ground, so that I can use on my 5th wheel? The safety on the trailer will not accept the power from my generator. Thank you
I have no info on that one.
GFM
Get a 3 prong plug. It'll be a dummy plug used for nothing but providing a grounded neutral. Make a short jumper from the ground terminal to the neutral terminal. Do not attached anything else to that plug - Close up plug and insert in any of the receptacles on the front of the generator - you now have a generator that will work just fine with a furnace or some trailers that are wired for grounded neutrals. Takes less than 5 minutes- problem solved
@@avflyguy thank you
How would you fix a floating hot?
I have never heard of a floating hot.
GFM
Question..........I live in a double wide Mobil home, I have a large main panel on a pole 20 foot away from my home , I think the neutral from the power company is connected inside the panel to ground, are you saying that when the power comes over to the home and into the main panel in the house, that the neutral should not be connected with the ground bar, if so , should there be a separate grounding stake to serve the ground from the panel in the home, and not connected to neutral.
That is correct. You can and should use a separate ground rod connected to earth ground at the panel ground.
GFM
The neutral from the power company should be connected inside the [first] panel to the panel's ground bar AND should be connected to a ground rod.
RJParker is wrong on this one. Checkout 550.11(A) & 550.16 of the NEC. DO NOT connect the neutral and ground together at the panel inside the structure. Any ground rod you may install at the structure should be connected to the ground bar, not the neutral. The chassis of the mobile home should be connected to the ground bar.
GFM
I stand corrected. GFM is correct that only the first panel should have the neutral and ground bars connected. I knew that but missed the fact there was an outside panel first.
Thanks everyone, So after further review, this is what I found, At the main box on outside pole (main panel), the neutral and ground are tied together with a bar. There are 4 cables coming to the inside box, 1. Li / L2 / Neutral / Ground. The ground ties inside ground bar sub panel inside) to main panel ground in main panel on pole. there is also a ground wire from inside panel to trailer frame. The ground bar and the neutral bar are not tied together on the inside sub panel. I installed new cables from the outside box to the inside box 2 years ago, and basically redid what was done before, but with all new cables, and put them in Sch 80.
Should the ground wire be wired between the Main and the sub panel ?
It sounds like the 2 prong transformer power supplies are safer than a 3 prong device like the tools since they isolate you from the AC mains voltage, is that right?
And do you have a link to the playlist you mentioned at the end about the electrical system in the US? I'd love to check it out, thanks
My take on a floating ground can be electronics that have a logic ground but that logic ground is not tied to the panel ground by design. However interconnected devices often will connect to each others floating ground. In a similiar fashion hvac control power is often floating on the common/ground side. It is possible to have a floating ground in an electrical panel because of a bad connection in the panel. This situation can sometimes burn out appliances especially when other items are incorrectly grounded at the appliance, including a previously acceptable neutral tied to equipment ground on three wire dryers and ranges. Floating neutrals are worse.
grayfurnaceman ...im getting the following readings on my digital multimeter ....120v from hot to neutral.... 70 v from hot to ground and lastlt 12v from neutral to ground on every receptacle in my dining room, what is the problem???
I would think you have a poor connection from neutral to earth ground. Probably in the main panel.
GFM
Or some weird leakage to ground that shouldn't be there. If the checking connections don't fix it: try flicking breakers on other branch circuits to see if the problem goes away.
Hey man, great stuff, I have an issue with my DJ mixer, i get small electric shocks when touching the metal screws and surface and a small tingle in my hands, now the back of the mixer output (AC) only has a 2 pin outlet (no ground) but routes into the main socket with a standard 3 pin UK plug (with ground), going by the manuals of the mixer i have it shows it has 3 pin output, but I have 2.. will this mean I need to go and have a ground put in the mixer? Or is it just a short somewhere, just asking your advice before I visit my local electronics store. Thanks
You have a short in the machine.
GFM
Are you an electrical engineering coz you know a lot I mean your knowledge is infinite and thanks for keep sharing it😀
My knowledge is definitely not infinite. My wife tells me so.
GFM
Can i connect the neutral (white wire) coming from the electrical panel to the neutral and ground (white and green) of the furnace if i do not have a ground coming from the panel?
I would not. Replace the wire from the breaker.
GFM
Thank you
On a electric outlet is it ok if I just tie gnd to neutral rather than just leave a floating gnd
I would not connect them together.
GFM
If I understand your question correctly that would be called boot legging and is very dangerous!!! You should never connect the ground to the common, or neutral on an outlet. A wall outlet tester will show you have it hooked up correctly but if you use a fluke it will show that you have 120 volts going from neutral to ground when it should read 0-1 volts. Hope this helped.
Very dangerous and will create objectionable current which could make your ground fault circuit become hot circuit.
@@LucifersDeathSquad yupper!!!
nice explanation,the teachers always taught us in hvac school that ground saves you from shock,i think it was evena test question
I used to think so too. Not so.
GFM
3 phase electric utilizes ground to run power back to panel, also single phase will run fine with hot and ground without neutral until the GFCI or AFCI comes into play
Basically its a bonding (the ground wire) is bonding the equipment togethore.
You are getting floating ground and no ground confused. Floating ground simply means the ground is not connected to the neutral.
There is no confusion. no ground is a floating ground.
GFM
My generator has a floating ground. The frame is connected to the ground, but is not bonded to the neutral. Your 2 prong plug on the jig saw is connected to the hot and neutral only. There is no ground to float, because it is not connected to ground.
@@grayfurnaceman - You're wrong and putting misinformation out there. floating ground means its not bonded to neutral. The actual earth doesnt absorb anything. Its not some magical place that current goes. The earth is actually a conductor. If you send current to the earth then the earth will be live. The only way to stop current is cut the source.
👍, I just doubt that ground is connected to neutral in panel.
What you need is ELCB to disconnect the electrical supply when the phase is short to ground.
ELCB: Earth Leakage Circuit Breaker.
My 1970 model pop up toaster has no safety ground connection. Hot and neutral conductor only. This is a floating ground, because it has no ground
fault connection. Conversely we know inside the main panel the Neutral
and the safety ground are BONDED together. Confusing, seem to be counter
to one another?
First, throw away that toaster.
The separation of neutral and ground at sub panels and appliances is necessary to keep the appliance from operating with an open neutral.
GFM
1:07 "... things you don't want ..." Would it be correct to say: In DC, ground IS the place all the electricity is trying to get to, and while it's trying to get there we put it to work. In AC, ground ISN'T the place all the electricity is trying to get to -- it's the place we send energy which isn't part of the AC push-pull action."
There is no ground in DC. In automotive uses, we may call it "ground" but it is just the second wire of the circuit. We use the chassis of the vehicle as one of the wires. Not always true in newer cars, as they use 2 wires in the circuit.
In AC, ground is not necessary for the circuit but we do, as you say, use it to dissipate surges and spikes.
GFM
so if my outlets don't have an earth ground is the world going to end?
Surge protection strips won't work as effectively, especially important for TVs and computers. Most older houses with two wire outlets are dangerous around wet locations. The safest thing to do on two wire systems is to install GFCIs at any location like baths and kitchens where severe shocks could occur.
We lived for many years without a ground on outlets. Grounded outlets are safer. I agree with RJParker on the GFCIs.
GFM
Great thanks. I agree on the GFCIs particularly in the kitchen and bath. It was somewhat of a smartarse question I know. I have learned a lot from your videos, keep 'em coming. I have tried to explain this chassis ground concept to a lot of people that see my 2 wire receptacles and I usually get a blank stare and a "uh ughhh uhh that's not safe" as response. Even people who should know better.
all electrical potential returns back to generator sub station via ground earth . Out side substations power plant generators there are large ground rod arrays buried under soil to neutral ground etc. Many are unaware of this.In wye star three phase industrial power systems (such as where power is generated at plant) the center tap is neutral to ground ( earth) and not used in Delta. Three phase primary power line transformers and sub stations all have earth ground which all power generated returns potential via ground. That is why you only see three wires on primary pole in street all hot between each phase in three phase commercial services and ground( earth neutral) for single phase house service. . No neutral between poles because the earth is used for such and pole transformer s usually have a neutral tap to earth.Study motor controls and Delta wye three phase schematic and find where center tap of wye goes....NEC has these diagrams. Nice show Thanks.
The only problem with this is it is not true. Earth ground has nothing to do with the circuit whether at the end users or the sub station.
GFM
~/~ Excellent explanation !!
Thanks guy
GFM
I work for Power authority and am an engineer. Ground(neutral) is earth to power prime mover at station. Verify
Am still shocked at how unsafe American plugs are in the UK we got rid of plugs like this 40 years ago
I hear a lot of UK commenters say this on various American electrical instructional videos. IMO, you Brits are overly paranoid and always have been when it comes to electrical code. You put fuses in 3 prong wires when such a thing is wholly unnecessary. If it were necessary our board at the NEC would have mandated it long ago. I mean this is America, we have an entire industry of lawyers looking to sue the first time little Johnny gets shocked by an unsafe device. If our plugs were that dangerous I guarantee any such company producing them would have been sued out of existence long ago.
You also do not allow any outlets or light switches in bathrooms which I think is insane. To my understanding all bathroom lights must be pull chain (correct me if I am wrong). In America we allow light switches on the wall in bathrooms and I have never heard of someone being seriously injured or killed from a light switch. Electrical outlets, yes, but not light switches (all outlets in bathrooms have to be GFCI protected here nowadyas because in the old days people were killed by hair dryers making contact with water).
(
With all respect teacher but I have a question
So, ask it.
GFM
In relation to Automotive electronics the term floating ground is related to some sensor grounds . The sensor grounds are usually on certain vehicles floating meaning means the ground is actually positive with a few hundred milivolts . Like Oxygen sensors , if you use an Oscilloscope on one and ground the scope to battery ground you'll see that it floats about .3V above what you would expect to see ( .1-.8V) . If you probe the sensor ground then you'll see it switching is reference to the 0V line being low reference . The do this to help reduce noise on sensors
The ground should be bonded at the panel and there should be a ground to the waterline or preferably a driven ground rod. A ungrounded tool is dangerous. this term floating ground is dangerous because when you use it, it is misleading the unaware. The fix is simple. Change the cord and drill and tap the metal screw the ground from the new cord to the tool.
You seem to be at odds with appliance manufacturers and the NEC. Computer power supplies, phone chargers and electric drills are just a few. Where would you drill and tap a phone charger to provide a chassis ground?
GFM
A floating ground means that there is a potential for you to become the ground.
Exactly right, which is why if you have a generator for your home, you really should do what your manual suggests, which is hook up an appropriately-sized ground wire. Otherwise, the frame of the generator could become energized and kill you. Lifelong electrician and 30 year electrical inspector.