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-   -   Wire size and breaker discrepancy (http://www.diychatroom.com/f18/wire-size-breaker-discrepancy-19703/)

Randell Tarin 04-09-2008 01:29 PM

Wire size and breaker discrepancy
 
I bought a Nutone bathroom heater/vent combo for a new install. The manufacturer's recommendation for the wire size and breaker is #14/3 on a 20 amp breaker.

I was under the impression that #14 was only rated at 15 amps. Are there some finer points I'm missing?

Jim Port 04-09-2008 02:06 PM

You are correct that a 20-amp circuit requires a circuit wired with #12.

hpp58 04-09-2008 02:15 PM

For branch circuits 14 gauge wire can only get a 15 amp breaker.
For dedicated circuits you can use a 20 amp breaker with 14 gauge wire, see 240.4D,

Jim Port 04-09-2008 03:01 PM

hpp58,

Could you please elaborate? When I read 240.4(D) it says nothing about dedicated circuits and seems to me to state very clearly that 14 ga. is limited to 15 amps.

Randell Tarin 04-09-2008 04:13 PM

This is a dedicated circuit.

HouseHelper 04-09-2008 04:23 PM

This is one of those instances where the manufacturer's recommendation is wrong. If it is a heater/vent (no light) you need to use 12/3 w/g on a 20A circuit. Using 14ga on a 20A is not permitted in this situation.

Stubbie 04-09-2008 05:14 PM

Randy

More accurately 240.4(D) restricts the protection of 14 awg to a 15 amp circuit breaker in your case. 14 awg copper is rated at 20 amps (table 310.16). There are situations where you can put a 20 amp breaker on 14 awg copper however this heater/vent combo is not one of them.

What is the model#?

Randell Tarin 04-09-2008 05:34 PM

Model No. 605RP

All the instructions say is: "Provide a separate 20 amp circuit. Use 14 GA power cable of type which meets code."

Sounded fishy to me.

Stubbie 04-09-2008 05:49 PM

Yeah it appears to be a screw up...not all that uncommon. I posted the links to nutone and at the bottom it shows the specification sheet and installation guide.

The specifications sheet says connect to a dedicated 15 amp branch circuit.

The installation guide says in bold type to be sure to use a 20 amp branch circuit.

http://www.nutone.com/product-detail...roductID=10150

Stubbie 04-09-2008 06:04 PM

I should add that the unit operates at 11.5 amps total. The heater is 1300 watts which makes it 10.8 amps and the motor would be another 3/4 of an amp or so. Since this is fixed space heat the heater would require conductors rated 13.5 amps. So a 15 amp branch circuit will do the trick.

Randell Tarin 04-09-2008 06:07 PM

Thanks Stubbie. I already had a roll of 14/3 I had bought for my smoke alarms. That saves me the expense of going out and buying 12/3 wire.

jerryh3 04-09-2008 07:06 PM

Quote:

Originally Posted by Joba Fett (Post 115036)
I'm new here, but some of this info being presented by so called "contractors" is poor at best. These DIYer's are going take this info without doing any credible research and take it as gospel.

Aren't there any moderators or whatever to watch out for this mis-information. This is very dangerous.

Isn't this credible research? There are plenty of licensed electricians on the board that will catch and correct any "mis-information" that is posted.
--A conservative liberal

nap 04-09-2008 09:13 PM

Quote:

Originally Posted by hpp58 (Post 114996)
For branch circuits 14 gauge wire can only get a 15 amp breaker.
For dedicated circuits you can use a 20 amp breaker with 14 gauge wire, see 240.4D,

Quote:

Originally Posted by Joba Fett (Post 115036)
I'm new here, but some of this info being presented by so called "contractors" is poor at best. These DIYer's are going take this info without doing any credible research and take it as gospel.

Aren't there any moderators or whatever to watch out for this mis-information. This is very dangerous.

while hpp58 did post incorrect information, it was caught and corrected by several others. There are also mods that do watch and correct when they do see a problem but many of the regulars here are electricians and do know the correct answers.

As a member of this forum, joba fett, if you see an incorrect post, you are hereby required to make a corrective post. As well, you may report that thread to the moderator who will look at the thread and attach their corrective post, if they believe it is needed.

and yes, electrical work is very dangerous. That is why most here do take it very seriously and do what they can to make sure correct info is provided.

chris75 04-09-2008 11:52 PM

Quote:

Originally Posted by Randell Tarin (Post 114981)
I bought a Nutone bathroom heater/vent combo for a new install. The manufacturer's recommendation for the wire size and breaker is #14/3 on a 20 amp breaker.

I was under the impression that #14 was only rated at 15 amps. Are there some finer points I'm missing?


THis is a misprint in their instruction manual, I've heard this one before...

hpp58 04-10-2008 10:51 AM

Thank you gentleman for pointing out my error.
I was responding to the original post, namplate information 14 gauge, 20 amp breaker.
There are some instances that you can have a 20 amp breaker on 14 gauge wire, the code allows it (see table 310.16)(422.62(B)(1)), but is only for certain applications, and/or if the manufacture specifies it.
Not in this case. I contacted Nutone and they confermed that it was a misprint and this unit should be wired with 12 gauge wire.


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