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  #1  
Old 10/9/06, 6:49 PM
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Default 30 amp breaker wire size

Lately I have run into many 30 amp pool equipment circuits run with 12awg wire. These have been in newer homes and have passed city inspection etc. My Code Check book says 30amp breakers get 10awg wire. Am I missing something here?
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  #2  
Old 10/9/06, 7:10 PM
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Jeffrey R. Pope, CMI Jeffrey R. Pope, CMI is offline
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Default Re: 30 amp breaker wire size

Quote:
Originally Posted by kweiss
These have been in newer homes and have passed city inspection etc.
Since when has that mattered?

Based on Table 310.16, 12AWG CU is allowed for 30 amps if it's Type TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, or ZW-2

Check the sheathing and it's probably THHN or THHW



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  #3  
Old 10/9/06, 7:17 PM
Speedy Petey Speedy Petey is offline
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Default Re: 30 amp breaker wire size

Yes. Breaker to wire size is not always black and white. Such as #10 on a 30 amp breaker.
Breaker sizes for motors, welders and A/C units follow different rules than other branch circuits. So to say #12 on a 30 amp breaker is wrong, is, well, wrong.

If the circuit is dedicated to the pump motor it very well may be legal for #12 to be on a 30 amp breaker.
A single phase motor on a dedicated branch circuit can have an ovecurrent device rated at 300% of full load current, yet the branch circuit conductors must be rated for the full load current at 125%. Current is valued by Tables in the code book according to motor type.

I must say, for residential applications I rarely use these figures. Too many times things are added to circuits,or circuits are changed and used for other loads.
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Old 10/9/06, 7:19 PM
Speedy Petey Speedy Petey is offline
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Default Re: 30 amp breaker wire size

Quote:
Originally Posted by jpope
Since when has that mattered?

Based on Table 310.16, 12AWG CU is allowed for 30 amps if it's Type TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, or ZW-2

Check the sheathing and it's probably THHN or THHW
Jeff, thing is, 240.4(D) typically over rules this for #14, #12 and #10.
I say typically because....see above post.
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  #5  
Old 10/9/06, 7:25 PM
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Default Re: 30 amp breaker wire size

Splain "Tap Conductor," if you would be so kind.



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  #6  
Old 10/9/06, 7:26 PM
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Default Re: 30 amp breaker wire size

Nevermind, I found it.



But I'm not sure I understand it.



IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ®
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  #7  
Old 10/9/06, 7:29 PM
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Paul W. Abernathy, CMI Paul W. Abernathy, CMI is offline
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Default Re: 30 amp breaker wire size

as Speedy says......# 10 AWG is good for 30A......and nothing MORE unless otherwise specified and allowed within the CODE.....as with motors and AC units and so on as Speedy stated.



Paul W. Abernathy
Manager, Electrical Codes & Standards
Encore Wire Corporation

“Promise me you'll always remember: You're braver than you believe, and stronger than you seem, and smarter than you think.” -RIP Dad, Love You!.10/10/2014

Disclaimer - All my posts on this forum are of my own personal opinion and in no way represent the opinions of Encore Wire, or other associations, organizations or affiliations.
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Old 10/9/06, 9:38 PM
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Default Re: 30 amp breaker wire size

normally when you see a residential motor load served by a larger wire than the breaker would normally allow, you will also see overcurrent protection at the motor disconnect itself at a lower rating.
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Old 10/9/06, 10:59 PM
Pierre Belarge Pierre Belarge is offline
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Default Re: 30 amp breaker wire size

Jeff
The tap conductors definition is located at 240.2.
For the benefit of those who do not have their NEC.

"Tap Conductors:
As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4."

(the bold and italicize are mine)

For instance:
conductors from a 2-pole 100amp breaker are installed to a trough. Those conductors are sized at 2 AWG copper.
In the trough there are 2 sets of other conductors (the taps). Each is spliced directly to the 2 AWG conductors without any overcurrent protection at the splice. Those 2 sets are sized at 6 AWG and 8 AWG respectfully. The 8 & 6 conductors each are installed to separate disconnects, the 8 AWG disconnect has a 50 amp overcurrent device at the disco, and the 6 AWG disco has a 60 amp overcurrent device at the disco.

Even though the overcurrent device ahead of the 8 & 6 is 100 amps, the tap rule in 240.21(B) permits this, if all of the applicable requirements of .21(B) are followed.
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Old 10/10/06, 11:23 AM
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Default Re: 30 amp breaker wire size

It seems to me that checking the wire type on the sheathing is somewhat above and beyond the scope of an inspection. I don't check ALL the wires for their type. Often older wire is hard to read the writing on the sheathing or situated in such a way that you cannot read it.

So would you call this out? Or assume that they are using a proper wire type in 12awg. Assuming seems dangerous and is not one of my preferred practices. I suppose you could write something explaining the situation. Is that overkill and unneccesary?
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  #11  
Old 10/10/06, 11:34 AM
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Default Re: 30 amp breaker wire size

It seems safe to say, that it should be called out as improper.



IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ®
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  #12  
Old 10/10/06, 4:42 PM
Speedy Petey Speedy Petey is offline
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Default Re: 30 amp breaker wire size

Quote:
Originally Posted by jpope
It seems safe to say, that it should be called out as improper.
I can see the generic idea that it would be considered wrong, but assuming it IS a legal motor circuit what wording would you use to convey that it is improper?

This is yet another reason I do not like to use these special rules regarding motors in a residential application.
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  #13  
Old 10/10/06, 5:19 PM
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Default Re: 30 amp breaker wire size

I can't see it as a "motor" circuit. Typically these conductors feed a panelboard with additional circuits for all of the pool equipment.



IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ®
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Old 10/10/06, 5:35 PM
Speedy Petey Speedy Petey is offline
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Default Re: 30 amp breaker wire size

No, I do not mean feeders. I do mean a motor circuit.

The OP states these are circuits for "pool equipment", so I read that as circuits, not feeders.

I am not being argumentative, I am merely trying to figure how this would be written up.
Possibly something like: "Possible undersized circuit conductors for pool equipment." Or something like that.
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  #15  
Old 10/10/06, 6:52 PM
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Default Re: 30 amp breaker wire size

I am assuming he was referring to feeders on a 30 amp breaker at the service equipment (I could be wrong).

In any event, if the inspector is unsure that the conductors are properly sized, the recommendation should state something like;

The conductors for the - (insert pool motor, equipment, etc.) - appear to be inadequately sized based on the rating of their OCPD. This circuit should be verified by a qualified electrician and serviced accordingly.



IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE ®
Jeff Pope
JPI Home Inspection Service
Santa Clarita CA
(661) 212-0738
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