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#82576 11/28/02 04:54 PM
Joined: Nov 2002
Posts: 7
B
Junior Member
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 09:17 AM
Joined: Jan 2001
Posts: 1,044
Tom Offline
Member
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."


Few things are harder to put up with than the annoyance of a good example.
#82578 11/29/02 09:24 AM
Joined: Nov 2002
Posts: 7
B
Junior Member
Thanks for our reply TOM

#82579 11/29/02 01:38 PM
Joined: Nov 2000
Posts: 2,148
R
Member
Look at 392.11(A). This section is not real clear to me, and (A)(1) appears to conflict with (A)(3).
Don


Don(resqcapt19)
#82580 11/29/02 03:20 PM
Joined: Jan 2001
Posts: 1,044
Tom Offline
Member
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?


Few things are harder to put up with than the annoyance of a good example.
#82581 11/29/02 10:58 PM
Joined: Jun 2001
Posts: 642
N
Member
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.


ed
#82582 12/06/02 09:49 AM
Joined: Nov 2002
Posts: 7
B
Junior Member
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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