Electric-Light
Senior Member
In the USA. What would you say the proper nominal service voltage is?
if the voltage across poles at dryer recep. is 215v the service voltage must be?
- Thread starter Electric-Light
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walkerj
Senior Member
- Location
- Baton Rouge
125 * 1.73 = 216.25
124 * 1.73 = 214.52
124 * 1.73 = 214.52
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I am not sure what the dryer has to do with it. If the voltage reading at the service is 215v which I would assume would be the same at the dryer then I would guess something is amiss.
- Location
- Massachusetts
At the service it could be certainly be 208 or it might be 240 running well under voltage.
At the dryer it could be either and still be within limits.
broadgage
Senior Member
- Location
- London, England
The actual service voltage will be close to the meter reading, it would be slightly higher at the service if the dryer was in use due to voltage drop in the wire to the dryer.
If the dryer outlet is connected to a sub panel, then the voltage at the service could be slightly higher due to voltage drop in the feeder to the sub-panel.
The voltage drop in the feeder or the dryer branch circuit would normally only be a few volts, but could be more in the case of long or undersized conductors.
The NOMINAL voltage of the service could be either 208 near the upper limit, or 240 volt near the lower limit.
In theory the nominal service could also be 200, 210, 220, or 230, but these are not standard voltages for USA residential service.
In practice the voltage from either hot to ground will determine the matter.
215 volts hot to hot with about 108 volts to ground would suggest a nominal 120/240 volt service with significant voltage drop.
215 volts hot to hot with about 125 volts hot to ground would sugest a nominal 120/208 service running at close to the maximum actual voltage.
If the dryer outlet is connected to a sub panel, then the voltage at the service could be slightly higher due to voltage drop in the feeder to the sub-panel.
The voltage drop in the feeder or the dryer branch circuit would normally only be a few volts, but could be more in the case of long or undersized conductors.
The NOMINAL voltage of the service could be either 208 near the upper limit, or 240 volt near the lower limit.
In theory the nominal service could also be 200, 210, 220, or 230, but these are not standard voltages for USA residential service.
In practice the voltage from either hot to ground will determine the matter.
215 volts hot to hot with about 108 volts to ground would suggest a nominal 120/240 volt service with significant voltage drop.
215 volts hot to hot with about 125 volts hot to ground would sugest a nominal 120/208 service running at close to the maximum actual voltage.
ptonsparky
Tom
- Occupation
- EC - retired
To many other factors, like voltage drop work into this. Is the Dryer On/Off? What is the total load at the transformer? Is it 100 degrees out in the middle of a densly populated area?
weressl
Esteemed Member
In residential areas the service most likely be 240/120V single phase, 3 wire.
In commercial service it would be either as above or 208/120V, 3 phase, 4 wire. (Of course larger, institutional users may have a 'service' delivered at MV and internal distribution steps it down, in the strictest sense that would not be the service, but the distribution voltage.)
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I voted for 240V because I was thinking 208V is not something dropped to residential customers in any place I have worked. But I hadn't considered that it might be a commercial application.
Oh wait, the thread topic actually SAYS residential dryer.
And a friend who does a lot of apartment building work tells me some complexes take a 120/208V 3 phase feed and break it out to single phase for each apartment, so in that case if the dryer is in there, it may be 208V too.
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Electric-Light
Senior Member
Dryer wasn't on. I just chose dryer, because dryer, stove and less commonly window shaker 15A/20A are usually the only line-to-line RECEPTACLES available in homes.
Washer receptacle fed from same panel was 125v.
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- Location
- Massachusetts
Almost all multi-unit apartments will be 208 and many city neighborhoods will have 208 volt services to single family homes.
kwired
Electron manager
- Location
- NE Nebraska
I don't understand the need for the poll. It is either a 208 volt supply running at the upper end of tolerances which is very common around here 215 is expected for unloaded 208 volt systems or it is a 240 volt system with very bad voltage drop. Most 240 volt systems here typically will measure 250 with no load.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
If this information was presented in the OP, I think everyone would have said it's a 120/208V service (2/3rds of a 3-phase 208/120V transformer). Since it's residential, I'm assuming it's a single-phase panel.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
OK now we're getting somewhere.
If the line was 120/240V sigle phase residential and the 215V measurement was indicating it was low, then 120V would be low by the same percentage and should have read around 107V.
It is was part of a 208Y120V 3 phase service and reading high at 215V, the Phase to Neutral voltage would be 215 / 1.732 = 124V. I call Bingo!
Can I change my vote?
Small apt building or residence 120/240, large apt complex 120/208, VERY LARGE apt complex or high rise condos 277/480 service or 2 services one at 120/208 one at 277/480.
If the dryer is off the voltage at the panel/sub panel it is fed from should be the same as at the outlet.
If the dryer is off the voltage at the panel/sub panel it is fed from should be the same as at the outlet.
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ptonsparky
Tom
- Occupation
- EC - retired
I waited for that small detail, so nope you can't change it now! To late.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Where is the "this poll is incomplete and silly" option? I'd vote for that.
It's akin to "I had ham and eggs for breakfast. What beverage did I have?" :roll:
It's akin to "I had ham and eggs for breakfast. What beverage did I have?" :roll:
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
110705-1213 EDT
George:
I agree.
There must be some other objective to this poll than is apparent. My initial reaction was not enough information, but with a stretch of one's imagination the answer could range from 200 to 240. This choice did not exist.
From a probability perspective and lacking information on why such a silly question was asked, I would select 208, but I think there is a trick to the question.
.
George:
I agree.
There must be some other objective to this poll than is apparent. My initial reaction was not enough information, but with a stretch of one's imagination the answer could range from 200 to 240. This choice did not exist.
From a probability perspective and lacking information on why such a silly question was asked, I would select 208, but I think there is a trick to the question.
.
M
MadWulf
Guest
M
MadWulf
Guest
Apartment buildings can vary on incoming service based on when they were built. Newer ones are 277/480 or 120/208 as they are commercial. Older ones are 120/240 delta....I truly dislike the wild leg!
All single family homes around here are 120/240 services.
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