MC Cable Vs Pipe & Wire

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Alwayslearningelec

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So if you have area with a bunch of receptacles circuits I'm curious when one would switch from pulling multiple neutral MC from homerun box by electrical closet to area where loads are.

Yes I understand after 9 CCC's you would need to use #10. So for say 6 circuits would you pull #10 MC w 6 hots & 6 Neutrals + ground or would you run out a 1" EMT with wires. Same for 7 and 8 circuits. Not sure what determines when would use one method over another. Thanks.
 
infinity

infinity

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We always run out 1" or 1.25" EMT homeruns to several locations and branch out from there with MC. For #10's and 20 amp circuits you put up to 20 ccc's in each homerun.
 
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Alwayslearningelec

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infinity said:
Probably cheaper in the long run. You end up with more terminations of EGC's with cable homeruns versus EMT.
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I'd think more terms of neutrals and hots too if you have to transition from cable to EMT right outside the closet although I'm thinking you may be able to make sure the MC is long enough to get to the panel then just take the jacket off the MC and feed the wires through the EMT thus eliminating having to terminate in the box. Make sense and can you do that/
 
infinity

infinity

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Alwayslearningelec said:
I'm thinking you may be able to make sure the MC is long enough to get to the panel then just take the jacket off the MC and feed the wires through the EMT thus eliminating having to terminate in the box.
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Yes you can do that too as long as your raceway fill and derating are correct. Opinions vary but I find it to be a bit sloppy but that's just me. When using 2 conductor MC cables it does add more EGC terminations in the panel. I would rather just run the MC directly into the panel and forget about the transition to EMT outside the closet.
 
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Alwayslearningelec

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infinity said:
Yes you can do that too as long as your raceway fill and derating are correct. Opinions vary but I find it to be a bit sloppy but that's just me. When using 2 conductor MC cables it does add more EGC terminations in the panel. I would rather just run the MC directly into the panel and forget about the transition to EMT outside the closet.
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I'm not following how EGC would vary in panel. Most all the time the spec call for EMT to leave panel to first box(not even sure the reasoning behind this). So each homerun pipe with receptacle circuits would only have 1 EGC...I believe. How does using 12/2 matter in regards to # of EGC in panel?
 
infinity

infinity

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Alwayslearningelec said:
I'm not following how EGC would vary in panel. Most all the time the spec call for EMT to leave panel to first box(not even sure the reasoning behind this). So each homerun pipe with receptacle circuits would only have 1 EGC...I believe. How does using 12/2 matter in regards to # of EGC in panel?
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If your homeruns are only EMT then you'll have an one EGC in each raceway. For example: 5 EMT's, 5 EGC's to terminate in the panel. If your homeruns are 12/2 MC cable then you'll have an individual EGC for each MC homerun in the panel. 42 circuits, 42 MC's, 42 EGC's to terminate in the panel.
 
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Alwayslearningelec

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infinity said:
If your homeruns are only EMT then you'll have an one EGC in each raceway. For example: 5 EMT's, 5 EGC's to terminate in the panel. If your homeruns are 12/2 MC cable then you'll have an individual EGC for each MC homerun in the panel. 42 circuits, 42 MC's, 42 EGC's to terminate in the panel.
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Correct. But I'm not sure there's many jobs I look at that allow MC out of panel.
 
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Alwayslearningelec

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infinity said:
If your homeruns are only EMT then you'll have an one EGC in each raceway. For example: 5 EMT's, 5 EGC's to terminate in the panel. If your homeruns are 12/2 MC cable then you'll have an individual EGC for each MC homerun in the panel. 42 circuits, 42 MC's, 42 EGC's to terminate in the panel.
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Even if MC was allowed to terminate in the panel that would be insane to run 12/2's. I'd think multi circuit MC would make more sense.
 
infinity

infinity

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Alwayslearningelec said:
Even if MC was allowed to terminate in the panel that would be insane to run 12/2's. I'd think multi circuit MC would make more sense.
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I agree it might make more sense to run out single cables with 4 circuits but there are other things that then need to be considered like the need for homerun boxes to split out the multiple circuits. You wouldn't need HR boxes with 2 wire homeruns.
 
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Alwayslearningelec

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infinity said:
I agree it might make more sense to run out single cables with 4 circuits but there are other things that then need to be considered like the need for homerun boxes to split out the multiple circuits. You wouldn't need HR boxes with 2 wire homeruns.
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Yes , but I would run out 4 ckt cable to box in area and the drop 12/2's from there. Your usually always going to have HR/splice boxes throughout.
 
T

texie

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In my view this one of those cases where there are a number of compliant ways to do things and the most cost effective way in labor and material will vary depending a lot on the distances involved between the various elements of the circuit.
 
infinity

infinity

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Alwayslearningelec said:
Your usually always going to have HR/splice boxes throughout.
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You won't need HR boxes with 2-wire home runs. Even with the added EGC's in the panel 2-wire HR's directly in to the panel is probably the least amount of labor. By how much I have no idea. Multi-circuit MC cables with HR boxes in the ceiling saves on the number of runs individual cables per circuit but adds the HR boxes at the end of each HR cable. EMT homeruns allows you to run a single raceway and gets lots of circuits to one area. If you're already running EMT out of the electric closet because they don't want exposed MC then IMO that's the best choice.
 
Jpflex

Jpflex

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infinity said:
Current Carrying Conductor (CCC) which factors into when they require derating.
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When you derate a feeder conductor supplying several motors, the feeder conductor cannot use the next size up OCPD for non standard ampacity as you could for feeders supplying non motor loads as modified for motor circuits such as feeders for sub panels in houses. Is this correct?

And when you size a feeder to a house sub panel you adjust its ampacity by either the larger of two ways

1) calculating the feeder ampacity to 125% of continuous loads and 100% of non continuous loads or

2 ) calculating the feeder ampacity to ambient temperature derating plus conductor bundling derating to meet the load requirement

Is this correct?
 
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