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jamiedolan 01-13-2009 11:18 AM

Wire size for dryer
 
HI;

I just want to verify that the wire size that was used in correct for my parrents dryer.

Name plate reads:

120/240 3 or 4 wire connection. I realize a 4 wire setup is required now.
It's Amp rating is at 28A. It was on 10awg with a 30A double pole breaker.

I only questioned it because it is rated (28A) so closely to the breaker size (30A) I am just wondering if since it is rated at more than 80% of the capicity of the circuit if it needs to be upsized?

Thanks so much
Jamie

rgsgww 01-13-2009 11:30 AM

It isn't a problem, you usually size loads to 80% when the load is long lasting. Like 3 hours or more.

You could double check with the manufacturer, they might have a max. over current protection and minimum over current protection.

If it is 3-wire, you could run a 10/3 line there. 8 awg is ok, but I think its a waste unless the distance is far.

Stubbie 01-13-2009 01:01 PM

There seems to be a lot of confusion about the 80% rule. This continues to drive me nuts.

80% rule equals = general purpose branch circuits serving more than one outlet. No single cord and plug appliance can exceed 80% of the branch circuit rating. Branch circuit rating = circuit breaker size.

Duplex receptacle = 2 outlets
Single receptacle = 1 outlet

Dryer branch circuit = branch circuit to a single outlet no other outlets..ie..an individual or dedicated branch circuit.

NEC 210.21(B)(1)

A single receptacle on a individual branch circuit shall have an ampere rating not less than the branch circuit rating. 30 amp breaker serving an individual branch circuit = 30 amp receptacle rating minimum.

NEC 210.23 Permissible Loads

An individual branch circuit shall be permitted to supply any load for which it is rated.

Dryer = 30 amp individual branch circuit, therefore it can be 100% of the branch circuit rating. So a 28 amp dryer is just peachy.

Quote:

Operating 3 hrs or more on a on going basis = continuous load = branch circuit conductors rated 125% of the equipments load for an individual branch circuit. 28 amps x 1.25 = 35 amps. Would require 8 awg copper conductors minimum for the branch circuit if using 60C column of table 310.16.
Your dryer is not a continuous load so this doesn't apply

Hope this helps

jamiedolan 01-13-2009 08:45 PM

Thank you for the explanation and the help
Jamie

Speedy Petey 01-13-2009 09:17 PM

Guys, what about

210.23(B) 30-Ampere Branch Circuits. A 30-ampere branch circuit shall be permitted to supply fixed lighting units with heavy-duty lampholders in other than a dwelling unit(s) or utilization equipment in any occupancy. A rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating.

chris75 01-13-2009 09:31 PM

I'll ask the simple question, what model did you buy that has a nameplate of 28 amps?

jamiedolan 01-13-2009 11:18 PM

Quote:

Originally Posted by chris75 (Post 212271)
I'll ask the simple question, what model did you buy that has a nameplate of 28 amps?


Not sure what brand it is, but will take a look and let you know. It is fairly new, just a few years old. Is that a weird rating for a dryer? I hope I am not an idiot that read the name plate wrong... I was using a flashlight... Guess I should push in some new wires for the light in there. too much to do..:laughing:

Will let you know tomorrow. Thanks
Jamie

Stubbie 01-13-2009 11:59 PM

I'm pretty sure but not positive that 210.23 (A) thru (D) is speaking about branch circuits supplying more than one (individual) outlet. 210.23 1st paragraph specifically IMO singles out individual branch circuits as being able to supply any load for which they are rated. Everything after that is talking about more than one outlet. 210.23(B) is talking about supplying more than one 30 amp outlet on the same 30 amp rated branch circuit.


Handbook commentary:

A branch circuit that supplies two or more outlets is permitted to supply only the loads specified in accordance to 210.23 (A) through (D) and summarized in table 210.24. Other circuits are not permitted to have more than one outlet and are considered individual branch circuits.

What say Ye??

InPhase277 01-14-2009 12:54 AM

I bet the plate said something like 23 A, and Jamie saw 28. Besides, as long as the wiring is protected by the correct size breaker, that's about all we really have to be concerned with from a safety standpoint.

Speedy Petey 01-14-2009 07:36 AM

And of course Stubbie is right. :jester:
It's what I don't read that kills me. You think you know something by heart for 20 years and still miss a sentence. :wink:

Stubbie 01-14-2009 09:03 AM

Quote:

Originally Posted by InPhase277 (Post 212358)
I bet the plate said something like 23 A, and Jamie saw 28. Besides, as long as the wiring is protected by the correct size breaker, that's about all we really have to be concerned with from a safety standpoint.

There you go trying to make things simple.......:)

Stubbie 01-14-2009 09:05 AM

Quote:

Originally Posted by Speedy Petey (Post 212397)
And of course Stubbie is right. :jester:
It's what I don't read that kills me. You think you know something by heart for 20 years and still miss a sentence. :wink:

This happens quite often when we actually stare at the code too long.....:laughing:

Gigs 01-14-2009 12:17 PM

Quote:

Originally Posted by Stubbie (Post 212019)
There seems to be a lot of confusion about the 80% rule. This continues to drive me nuts.

80% rule equals = general purpose branch circuits serving more than one outlet. No single cord and plug appliance can exceed 80% of the branch circuit rating. Branch circuit rating = circuit breaker size.


I'm more confused now. Wouldn't a 1500 watt coffee maker on a 15 amp circuit violate this then?

Or lets say I put all 20 amp outlets on my 12 gauge circuit... The biggest load I can plug into any one of them is 16 amps? Really?

Stubbie 01-14-2009 07:47 PM

The only people that would really know these requirements would be electricians or someone familiar with the NEC. The typical homeowner will plug anything they want in the receptacle. The NEC can not control what you plug into an outlet. The intent is to not consume the entire branch circuit rating with one appliance since there are other receptacles on the branch circuit ... possibly lights and other loads both fixed and cord and plug.

In my opionion these code sections are more for recommendations to the electrician so he will design his circuits to prevent reasonable overloads from cord and plug equipment that he knows will be on the branch circuit.

jamiedolan 01-15-2009 06:43 AM

It is a Whirlpool Dryer. Will get a photo of the name plate and post it.

I looked again, but, have to take a photo, it looks like 28, but is printed pretty small.

Ran across this on the Iaei.org site tonight:

Question 7. Is a 28-amp electric clothes dryer plugged in to a 30-amp individual branch circuit in compliance with the permissible loads of NEC 210.23, or does the 80 percent rule apply? — E.K.
Answer 7. Section 210.23 [NEC 2002] states, "In no case shall the load exceed the branch-circuit ampere rating. An individual branch circuit shall be permitted to supply any load for which it is rated. A branch circuit supplying two or more outlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as summarized in 210.24 and Table 210.24." Section 210.23(B) states, "30-Ampere Branch Circuits. A 30-ampere branch circuit shall be permitted to supply fixed lighting units with heavy-duty lampholders in other than a dwelling unit(s) or utilization equipment in any occupancy. A rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating."
Thus, the question asks if a 28-ampere load is acceptable on a 30-amp individual branch circuit, and the answer is yes, as long as that is the only utilization equipment on that circuit with one outlet or receptacle. The 80 percent rule applies when two or more outlets or receptacles are installed per 210.23(A) through (D). — Raymond W. Weber


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