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stevena 730 · Dec 16, 2006, 07:16 AM

I had my electric service upgraded 18 years ago and had the electrician install two GFCI's,
One for the bathroom and one for the kitchen. They are on separate circuits by themselves. They are each on a 20 amp breaker with 12 gauge wire and the GFCI's are rated 15 amp with 20 amp feed through.
My question is should the GFCI's be rated 20 amp with 20 amp pass through? We've never tripped a breaker, however my wife recently bought a blow dryer of 1875 watts, which still hasn't tripped the breaker.

Also the outlets in my kitchen are rated for 15 amps, but are on a 20 amp breaker with 12 gauge wire. Should I replace them with 20 amp outlets? We've never tripped those either.

Thanks,

Steve

andrewcocke · Dec 16, 2006, 12:08 PM

20 AMP outlets have a special prong that is turned on its side for appliances and other electroics that have the special 20 amp plug.

A 15 AMP outlet on a 20 amp circuit just means that you won't be able to plug anything with the 20 amp plug into that outlet. Will it hurt anything to have a 15 amp plug on a 20 amp circuit? I wouldn't think so, any appliance or electronic that REQUIRES a 20 amp circuit should be wired with the special 20 amp plug, thus requiring the special 20 amp outlet to plug into. Ive never ran into anything in the hosue that has the special plug with the exeption of maybe some window air conditoners.

You could change them over if you wanted to, wouldn't hurt anything, the circuit is already rated for the 20 amp outlet, you could get the 15-20 outlet, this kind can accept both 15 and 20 amp plugs.

See attachment below for the 15-20 amp plug:
NOTE: DO NOT install these on 15 amp circuits on 14 gauge wire, only 20 amp circuits.

Morrowrj · Dec 17, 2006, 05:34 AM

Also, depending on how strong your line voltage is, the hair dryer is going to put you right on the edge of the 15 amp limit, assuming it was ran at the highest setting.

tkrussell · Dec 17, 2006, 06:22 AM

What does strong line voltage have to do with this issue?

Morrowrj · Dec 17, 2006, 06:41 AM

Well, if his line voltage was lets say, 110volts , then the 1875 watt dryer would (approximately) draw 17 amps at full heat. If the line voltage was 128 lets say, then it would only draw 14.5 amps. I know these differences are slight, but my point is a slight fluctuation in line voltage (hot summer day) and this could all of a sudden trip when it had worked fine for months

tkrussell · Dec 17, 2006, 07:55 AM

Ok that is a better explanation to Stevena, however a bit hypothetical.

Nominal voltage supplied by utilities in North America is 120 volts. Utilities are mandated to provide this voltage within certain guidelines, typically plus/minus 5%, so the span is 114 volts to 126 volts at the point of service.

In reality, these high and low voltages occurrences are rare, thou low voltage is more possible in summer due to the high air conditioning load as you refer to.

If the voltages were to go as low as 110 volts or as high as 128 volts, there would be plenty of other problems caused to be concerned with.

Stevena seems to be wondering why the 20 amp breaker is not tripping, and seems to think that because the outlet is rated 15 amps and the breaker is rated 20 amps, there should be some relationship to tripping.

Technically, outlets on a 20 amp circuit should be 20 amp rated, but having 15 amp devices on a 20 amp circuit is fine, the circuit should not exceed a 15 amp draw simply because the outlet will not allow a full 20 amp appliance to use the outlet.

A hair dryer is only on a very short time, at 1875 watts and 120 volts the current draw should be 15.625 amps. This amp draw exceeds the 15 amp rating of a 15 amp outlet.

Outlets are not designed to handle just exactly the amount of rating, and can handle a certain amount of over current for a short time, due to over engineering to allow a safety factor. And this dryer does come with a 15 amp plug, and is UL listed, or at least should be.

A 15 amp device is actually a 20 amp inside, but only allows a 15 amp appliance to be plugged into it because of the receptacle opening configuration to limit the usage on a true 15 amp circuit with #14 wire and a 15 amp breaker.

Breakers are also very forgiving, they do not trip as soon as the draw gets close to the rating, as breakers are inverse time devices, in other words they allow more current to pass initially, and will trip after some time has passed.

stevena 730 · Dec 17, 2006, 03:39 PM

Thank you all for your answers.

Steve