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#82576 - 11/28/02 12:54 PM Table 310.15(B)(2)(a)
Bobby Mercier Offline
Junior Member

Registered: 11/28/02
Posts: 7
Loc: St-Georges,Quebec,Canada
If i use 3c10awg MC cable for cabling 10 hp 460V motors, in accordance with table 310.15(B)(2)(a), i can make a bunch of 10 of this cable. My question is how many space it should have bettween this bunch of cables and another bunch of cables. (i mean in a ladder cable tray)

[This message has been edited by Bobby Mercier (edited 11-28-2002).]

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#82577 - 11/29/02 05:17 AM Re: Table 310.15(B)(2)(a)
Tom Offline
Member

Registered: 01/01/01
Posts: 1069
Loc: Shinnston, WV USA
Space means just that, as in no contact between the bundles. Since no specific dimension is given, if you can see a crack of light between the bundles, they meet the definition of the word "spaced."
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#82578 - 11/29/02 05:24 AM Re: Table 310.15(B)(2)(a)
Bobby Mercier Offline
Junior Member

Registered: 11/28/02
Posts: 7
Loc: St-Georges,Quebec,Canada
Thanks for our reply TOM

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#82579 - 11/29/02 09:38 AM Re: Table 310.15(B)(2)(a)
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
Look at 392.11(A). This section is not real clear to me, and (A)(1) appears to conflict with (A)(3).
Don
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#82580 - 11/29/02 11:20 AM Re: Table 310.15(B)(2)(a)
Tom Offline
Member

Registered: 01/01/01
Posts: 1069
Loc: Shinnston, WV USA
Don has a very good point & I could see a fistfight or two breaking out over it. Maybe you need to space the bundles 1 bundle diameter apart.

I feel I correctly answered your question about space in the ordinary sense, but I didn't do so in the context of your question.

In any case, since you are dealing with #10 conductors, it appears that 310.15(B)(2)(a) would require a derating to 45%. Therefore, #10 would be OK since its final ampacity is more than 125% of the 14 amps the motor draws.

It would be interesting to apply Exception 5 to 310.15(B)(2)(a) by using #12 & supporting on bridle rings instead of cable tray. What do you think?
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#82581 - 11/29/02 06:58 PM Re: Table 310.15(B)(2)(a)
nesparky Offline
Member

Registered: 06/21/01
Posts: 650
Loc: omaha,ne
Don
I believe that 392.11(A)(1) applies to the cable assembly. eg a 10-3 mc cable vs a 10-5 mc cable where you may have more than 3 current carring conductors in that one cable.
I believe that 392.11(A)(3) applies to the total # of cable assemblies installed in the tray.
Keeping cable assemblies seperated is a good practice.
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ed

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#82582 - 12/06/02 05:49 AM Re: Table 310.15(B)(2)(a)
Bobby Mercier Offline
Junior Member

Registered: 11/28/02
Posts: 7
Loc: St-Georges,Quebec,Canada
I think if i respect table 392.9 i don't have to derate cable.

Do you thing it's OK

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