using 75 degree rating for conductor

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tommyrice

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I just had a disagreement with a friend of mine dealing with the allowable ampacity of a #14 thwn conductor to a 10 amp pool pump.I told him as long as the pump terminations were rated for 75 degrees and breaker was 75 degrees the phase wires could be #14 under a 20 amp breaker.He disagreed with me. I told him equip. grnding cond. had to be #12 but hot legs could be # 14 under these circumstances. Am I right?
 
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sbrehler

Member
I believe that 2011 NEC 240.4 (D)(3) has the answer to your question.

(D) Small Conductors. Unless specifically permitted in
240.4(E) or (G), the overcurrent protection shall not exceed
that required by (D)(1) through (D)(7) after any correction
factors for ambient temperature and number of conductors
have been applied.

...
(3) 14 AWG Copper. 15 amperes
 
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texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
sbrehler said:
I believe that 2011 NEC 240.4 (D)(3) has the answer to your question.

(D) Small Conductors. Unless specifically permitted in
240.4(E) or (G), the overcurrent protection shall not exceed
that required by (D)(1) through (D)(7) after any correction
factors for ambient temperature and number of conductors
have been applied.

...
(3) 14 AWG Copper. 15 amperes
Click to expand...

240.4(D) does not apply in the example provided by the OP. 240.4(G) rules here. The #14 conductor in this case is correct, and the OCPD could be even larger than the 20 amp he used.
 
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sbrehler

Member
texie said:
240.4(D) does not apply in the example provided by the OP. 240.4(G) rules here. The #14 conductor in this case is correct, and the OCPD could be even larger than the 20 amp he used.
Click to expand...

Sorry, my bad...
Recently took my exam so, of course, I think know everything! :ashamed1:
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
IMO you could use 14 awg with a #12 EGC on a 20 amp cir. As stated 240.4 (G) comes into play and if the termination are rated 75 C then #14 is fine at 20 amps.

Also remember that the OCPD can be rated 250% of the full load current. A 10 amp motor with 14 amp conductors and a #12 EGC could then be protected at 25 amps and avoid using a GFCI breaker.
 
jumper

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
iwire said:
We could also use a 14 AWG EGC as the EGC is never required to be larger than the circuit conductors.
Click to expand...

I thought so also, but I do not know how to deal with this then:

680.21(A)(1)The branch circuits for pool-associated motors......
Any wiring method employed shall contain an
insulated copper equipment grounding conductor sized in
accordance with 250.122 but not smaller than 12 AWG.


:?
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
jumper said:
I thought so also, but I do not know how to deal with this then:

680.21(A)(1)The branch circuits for pool-associated motors......
Any wiring method employed shall contain an
insulated copper equipment grounding conductor sized in
accordance with 250.122 but not smaller than 12 AWG.


:?
Click to expand...

OK, I did not know about that one, being in a later chapter it trumps 250.
 
infinity

infinity

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Location
New Jersey
Occupation
Journeyman Electrician
iwire said:
We could also use a 14 AWG EGC as the EGC is never required to be larger than the circuit conductors.
Click to expand...

I thought about that too, but 250.122(A) seems to be in direct conflict with 680.21(A)(1). What does the NEC Manual of Style say?

250.122 Size of Equipment Grounding Conductors.
(A) General. Copper, aluminum, or copper-clad aluminum
equipment grounding conductors of the wire type shall not
be smaller than shown in Table 250.122, but in no case
shall they be required to be larger than the circuit conductors
supplying the equipment. Where a cable tray, a raceway,
or a cable armor or sheath is used as the equipment
grounding conductor, as provided in 250.118 and
250.134(A), it shall comply with 250.4(A)(5) or (B)(4).
Click to expand...



680.21 Motors.
(A) Wiring Methods. The wiring to a pool motor shall
comply with (A)(1) unless modified for specific circumstances
by (A)(2), (A)(3), (A)(4), or (A)(5).
(1) General. The branch circuits for pool-associated motors
shall be installed in rigid metal conduit, intermediate
metal conduit, rigid polyvinyl chloride conduit, reinforced
thermosetting resin conduit, or Type MC cable listed for the
location. Other wiring methods and materials shall be permitted
in specific locations or applications as covered in
this section. Any wiring method employed shall contain an
insulated copper equipment grounding conductor sized in
accordance with 250.122 but not smaller than 12 AWG.
Click to expand...
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
infinity said:
I thought about that too, but 250.122(A) seems to be in direct conflict with 680.21(A)(1). What does the NEC Manual of Style say?
Click to expand...

I don't have the NEC handy but a section of Artcile 90 tells us that the later chapters modify or supplement the earlier chapters.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
So 680 trumps 250. :D

90.3 Code Arrangement. This Code is divided into the
introduction and nine chapters, as shown in Figure 90.3.
Chapters 1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7
apply to special occupancies, special equipment, or other special
conditions. These latter chapters supplement or modify the
general rules. Chapters 1 through 4 apply except as amended
by Chapters 5, 6, and 7 for the particular conditions.
Click to expand...
 
Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I have no doubt that 680 trumps 250. The only issue I would have is whether #14 would be allowed. I see no reason for it to be disqualified but 680 clearly states 12awg min. EGC. You could almost be assured that 12 awg circuit conductors would be used in most all cases.
 
jumper

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
Dennis Alwon said:
I have no doubt that 680 trumps 250. The only issue I would have is whether #14 would be allowed. I see no reason for it to be disqualified but 680 clearly states 12awg min. EGC. You could almost be assured that 12 awg circuit conductors would be used in most all cases.
Click to expand...

Yeah, I would say this backs that up. As many times as I have read 250.4, you would have thought I would have seen this before.:slaphead:

250.3 Application of Other Articles. For other articles
applying to particular cases of installation of conductors
and equipment, grounding and bonding requirements are
identified in Table 250.3 that are in addition to, or modifications
of, those of this article.
 
Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
It would make it less confusing if they just insisted on the circuit being run in a minimum of 12awg. I must say I have never seen an inground pool done with anything less than a 20 amp circuit.

I would also love to know why an inground pool of 20 amps or less must be gfci protected when we know they make gfci up to 50 amp.

Also there is no 3 phase gfci so no larger pools are gfci protected so why do we need it?? i have no issues using it but before 2005 we never wired the pumps with GFCI-- Why now since none of the other pools above 20 amp need it.
 
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