the building has a 120/208 three phase service in it. Each meter/sub panel is getting TWO of the three phases of the three phase service. So you still have 120/208 voltage service on a "single phase" panel. If it was a true single phase (split phase), and you were getting 121 black to ground and 121 red to ground, you would be getting 242 black to red. Resistive heating appliances with provide about 75% the output with 208 input vs 240 input
The building service is 208Y/120V 3-phase 4-wire, but you are looking at a 1-phase meter/main with a 1-phase panel (line-to-line is 208V and line-to-neutral is 120V). This is very common with buildings like larger apartment complexes that need a large 3-phase service to run the entire group of apartment units, but each apartment only gets a single-phase feed and loadcenter (panel). The multiple 1-phase feeds will alternate which phases they are tapped from (A-B, B-C, and C-A) to distribute the load amongst all 3 phases.
Non-electrician here. I love learning about this stuff. I'm too old to become an electrician. But having read all the comments, they make sense. I would never have thought of 2 phases coming in instead of split phase. You all figured that out based on the voltages of both separate lines. That is cool.
@@uthus2000 I didn't want to mention this in my comments, but I'm also disabled. It's a "mental" thing. I find I cannot stand as a result of my childhood abuse when someone is wrong and says I'm wrong when I'm not. By all means, correct me if I've made a mistake and then let me fix it. Apparently that concept is not the way some people work. After falling apart and losing my computer security subcontracting business, I did try to work again at Home Depot. But again, someone told me I was doing it wrong, but I wasn't. I flew off the handle and quit. It was my boss that did that. I was making customers happy by getting them what they needed and restocking shelves as items were returned. (Plumbing no less...I don't prefer plumbing). So after working 29 years, I'm home on disability and it sucks. But I do appreciate your encouragement to get back out there. I wish I could function in the real world, but SIL.
We used to get 3 phase grounded delta service. The panel looked just like the panel above. The standard 120/240 panel was located right next to it. Very confusing.
Because this appears to be a large multifamily dwelling, what you actually have is 120/208 single phase. 208V give or take some is derived from two phases of a 208Y/120V service. A split phase system like you would see in a single family dwelling, smaller multifamily dwellings and very light commercial, would have 240V line to line, 120V line to neutral. The only way you could have 240V phase to phase in a 3 phase system would be in a delta system which may or maynot provide a neutral to allow for 120 volt loads. A 240V delta system with a neutral will have 120 volts available between two phases to neutral, typically A and C but sometimes A and B in systems installed before the mid 1970s. The other phase to neutral would be 208 volts, this is known as the high leg and is required to be colored orange because it cannot be used for line to neutral loads, this system is typically used in industrial facilities where a vast majority of equipment are 3 phase motors and 240 volt single phase equipment, with very limited 120 volt equipment. For these reasons most 240V major appliances intended for residential and light commercial use will list separate wattage and/or ampere ratings for 208V and 240V.
I appreciate your responding. There are 18 units coming off the service gear plus the public panel. Being a residential, 3ϕ is outside what I normally see.
A 240v heater that is connected to 208v will not have the same output. The resistance of the heater is the same but the voltage changes which means the watts will also change. Example: A 3000 watt 240v heater has a resistance of 19.2 ohms. If you connect that same 19.2 ohm heater to 208 you will only get 2253 watt output. The only way you can correct for this is to install a 16/32 buck/boost transformer.
Yeah. I understand all that. The heater and the a/c condenser outside are both dual voltage. I just wasn't expecting a 208y/120. I'm primarily residential and I think this is the second 3ϕ I've worked on in 8 years. Thanks for your insight.
With unequally divided pair of 3-phase power, it's not as simple as Watts = voltage squared divided by resistance. That assumes constant (DC) volts, and these are AC with an attitude. Rectify and filter the 120 degree 208, you'll get the same DC voltage out as you would with 180 degree 240. Weird but true. Requires integral calculus to explain why, so just go with it.
If it was true single phase then L-L would be exactly 2x of L-N. Since L-N is 121, L-L should be 242. 214 is indicative of 2 legs of (nominal) 208 wye voltage.
Is it because of the red line coming in and the white neutral that makes it 3 phase ? Shouldn't you have 2 blacks coming in if it was a single phase. I dont know much about this.
@@supersawyer358Exactly, the utility is providing 3 phase but the meters are single phase thus each meter is only getting two of the phases. There is no legal way to get three phase out of those meters. This is very common for apartments and condos. This is really two phase as the angle between the phases causes them to add up to only 208VAC nominal instead of 240VAC for a "normal" single phase service. This is unfortunate for some loads designed for 240V as you won't get full power out of them. You can put a boost transformer, or learn to live with it.
@@supersawyer358Electrons are color blind. They don't know about wire color. In order to have 3 phase, you must have three hot wires coming in that are normally black, red, and blue. He only has two hots coming in (black and red) so no 3 phase. I am sure there is 3phase inside the meter cabinet but only two of the phases are wired to each meter and they alternate for balancing the load.
@crissd8283 ok 👍 i thought so and wasn't sure. I know enough about electric to be dangerous. I've wired lots of things but always had it looked over by an actual electrician.
The finding of 214VAC between lines is the clue that the lines are nominal 208V.
It's a wye not a delta.
the building has a 120/208 three phase service in it. Each meter/sub panel is getting TWO of the three phases of the three phase service. So you still have 120/208 voltage service on a "single phase" panel. If it was a true single phase (split phase), and you were getting 121 black to ground and 121 red to ground, you would be getting 242 black to red. Resistive heating appliances with provide about 75% the output with 208 input vs 240 input
Thanks. I never see it, so I wasn't expecting it.
The building service is 208Y/120V 3-phase 4-wire, but you are looking at a 1-phase meter/main with a 1-phase panel (line-to-line is 208V and line-to-neutral is 120V). This is very common with buildings like larger apartment complexes that need a large 3-phase service to run the entire group of apartment units, but each apartment only gets a single-phase feed and loadcenter (panel). The multiple 1-phase feeds will alternate which phases they are tapped from (A-B, B-C, and C-A) to distribute the load amongst all 3 phases.
Thanks. I did finally realize what was going on. It was a learning experience.
Non-electrician here. I love learning about this stuff. I'm too old to become an electrician. But having read all the comments, they make sense. I would never have thought of 2 phases coming in instead of split phase. You all figured that out based on the voltages of both separate lines. That is cool.
I figure you're not too old unless you're dead. I didn't go to school until I was 50.
@@uthus2000 I didn't want to mention this in my comments, but I'm also disabled. It's a "mental" thing. I find I cannot stand as a result of my childhood abuse when someone is wrong and says I'm wrong when I'm not. By all means, correct me if I've made a mistake and then let me fix it. Apparently that concept is not the way some people work.
After falling apart and losing my computer security subcontracting business, I did try to work again at Home Depot. But again, someone told me I was doing it wrong, but I wasn't. I flew off the handle and quit. It was my boss that did that. I was making customers happy by getting them what they needed and restocking shelves as items were returned. (Plumbing no less...I don't prefer plumbing).
So after working 29 years, I'm home on disability and it sucks. But I do appreciate your encouragement to get back out there. I wish I could function in the real world, but SIL.
We used to get 3 phase grounded delta service. The panel looked just like the panel above. The standard 120/240 panel was located right next to it. Very confusing.
Because this appears to be a large multifamily dwelling, what you actually have is 120/208 single phase. 208V give or take some is derived from two phases of a 208Y/120V service. A split phase system like you would see in a single family dwelling, smaller multifamily dwellings and very light commercial, would have 240V line to line, 120V line to neutral.
The only way you could have 240V phase to phase in a 3 phase system would be in a delta system which may or maynot provide a neutral to allow for 120 volt loads. A 240V delta system with a neutral will have 120 volts available between two phases to neutral, typically A and C but sometimes A and B in systems installed before the mid 1970s. The other phase to neutral would be 208 volts, this is known as the high leg and is required to be colored orange because it cannot be used for line to neutral loads, this system is typically used in industrial facilities where a vast majority of equipment are 3 phase motors and 240 volt single phase equipment, with very limited 120 volt equipment.
For these reasons most 240V major appliances intended for residential and light commercial use will list separate wattage and/or ampere ratings for 208V and 240V.
I appreciate your responding. There are 18 units coming off the service gear plus the public panel. Being a residential, 3ϕ is outside what I normally see.
A 240v heater that is connected to 208v will not have the same output. The resistance of the heater is the same but the voltage changes which means the watts will also change. Example: A 3000 watt 240v heater has a resistance of 19.2 ohms. If you connect that same 19.2 ohm heater to 208 you will only get 2253 watt output. The only way you can correct for this is to install a 16/32 buck/boost transformer.
Yeah. I understand all that. The heater and the a/c condenser outside are both dual voltage. I just wasn't expecting a 208y/120. I'm primarily residential and I think this is the second 3ϕ I've worked on in 8 years.
Thanks for your insight.
With unequally divided pair of 3-phase power, it's not as simple as Watts = voltage squared divided by resistance. That assumes constant (DC) volts, and these are AC with an attitude. Rectify and filter the 120 degree 208, you'll get the same DC voltage out as you would with 180 degree 240. Weird but true.
Requires integral calculus to explain why, so just go with it.
Just say it's a 2 phase panel
If it was true single phase then L-L would be exactly 2x of L-N. Since L-N is 121, L-L should be 242. 214 is indicative of 2 legs of (nominal) 208 wye voltage.
Thanks.
I work residential and this is the 2nd 3ϕ I've seen in 8 years. Stumped me for a bit.
This dude is confused. He clearly has a 3 phase service and single phase panels. 120/208 is the correct voltage. Some people scare me......
Is it because of the red line coming in and the white neutral that makes it 3 phase ? Shouldn't you have 2 blacks coming in if it was a single phase. I dont know much about this.
@@supersawyer358Exactly, the utility is providing 3 phase but the meters are single phase thus each meter is only getting two of the phases. There is no legal way to get three phase out of those meters. This is very common for apartments and condos. This is really two phase as the angle between the phases causes them to add up to only 208VAC nominal instead of 240VAC for a "normal" single phase service. This is unfortunate for some loads designed for 240V as you won't get full power out of them. You can put a boost transformer, or learn to live with it.
@@supersawyer358Electrons are color blind. They don't know about wire color. In order to have 3 phase, you must have three hot wires coming in that are normally black, red, and blue. He only has two hots coming in (black and red) so no 3 phase. I am sure there is 3phase inside the meter cabinet but only two of the phases are wired to each meter and they alternate for balancing the load.
@crissd8283 ok 👍 i thought so and wasn't sure. I know enough about electric to be dangerous. I've wired lots of things but always had it looked over by an actual electrician.
You can use red and black or 2 blacks. Neutral can be black but must be marked with several inches of white tape .