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Old 08-06-2010, 11:39 AM   #16
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Ground wire when multiple branches run through same conduit


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Originally Posted by darren View Post
Do you plan on running a neutral with each hot, if so there is nothing wrong with this plan.
That was the plan.

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Could you not use multiwire branch circuits and save yourself some wire. This would also reduce your current carrying conductors(if the rules are the same in the USA) down to 4 instead of 8. Won't make a difference on wire size but with a couple less wires in the pipe it may be easier to pull the wire in.
I guess there's no big reason I couldn't do this. I'd have to rearrange stuff in the service panel since one phase (sorry if that's not the right term) is filled up and the the other has all the open spots. But since it's not particularly well load balanced between the two phases as is maybe that's not a bad thing.

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Old 08-06-2010, 02:19 PM   #17
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Ground wire when multiple branches run through same conduit


Phases alternate down each side. So unless you have every other space empty you have room on both phases.
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Old 08-06-2010, 02:46 PM   #18
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Ground wire when multiple branches run through same conduit


Don't forget to use handle ties or a 2-pole breaker if you plan to do a MWBC.
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Old 08-06-2010, 02:58 PM   #19
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Ground wire when multiple branches run through same conduit


There is little point to try to "balance" a panel in a residential setting. The location of the loads shift too much and you would need to realign the breakers at different time period due to changes in use based on time of day.
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Old 08-06-2010, 03:45 PM   #20
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Ground wire when multiple branches run through same conduit


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Phases alternate down each side. So unless you have every other space empty you have room on both phases.
Ah yes, thanks. heh. Otherwise a double pole breaker wouldn't have 240 across it. anyway I'll probably just do the original plan unless I have trouble pulling that many wires through.
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Old 08-08-2010, 01:39 PM   #21
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Ground wire when multiple branches run through same conduit


I have another question I can't find the exact answer to in my books. In the case of EMT to a junction box and then MC from the junction box to an outlet box, do I still have to pigtail the EGC and attatch it to the outlet box? In other words does the wrap of MC cable count as a connection for the outlet box. [Note that I'm only talking about the ground connection of the box, not the outlet. The EGC would of course get connected directly to the outlet.]

I managed to pull 9 wires through but I went with 3/4 EMT to do it. Probably would have been very hard with 1/2".
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Old 08-08-2010, 07:07 PM   #22
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Ground wire when multiple branches run through same conduit


Anytime you make a connection inside a box, the box must be grounded.
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Old 08-08-2010, 11:21 PM   #23
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Ground wire when multiple branches run through same conduit


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Anytime you make a connection inside a box, the box must be grounded.
Understood, but what I'm wondering is if the connection via the metal jacket of the MC cable is acceptable as the ground connection to the box or if it's mandatory to connect the EGC to the box even though there will also be a ground connection via the jacket. I presume the latter since the jacket can't be used as the EGC but I don't see this spelled out in the books I have.
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Old 08-09-2010, 09:04 AM   #24
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Ground wire when multiple branches run through same conduit


The armor of MC is not considered an EGC.

The armor of BX is considered an EGC because it has the bonding strip inside.
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Old 08-09-2010, 09:32 AM   #25
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Ground wire when multiple branches run through same conduit


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The armor of MC is not considered an EGC.

The armor of BX is considered an EGC because it has the bonding strip inside.
I understand that, which is why I said it's presumably not an acceptable connection for the box. To put it another way I'm wondering if the NEC differentiates between the ground connection required for the box and that for the outlet (I don't know why it would but it seems possible.) Obviously the EGC of the MC goes to the outlet as always.
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Old 08-09-2010, 05:38 PM   #26
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Ground wire when multiple branches run through same conduit


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Originally Posted by Ptron View Post
I understand that, which is why I said it's presumably not an acceptable connection for the box. To put it another way I'm wondering if the NEC differentiates between the ground connection required for the box and that for the outlet (I don't know why it would but it seems possible.) Obviously the EGC of the MC goes to the outlet as always.
not sure what the confusion is. When you bring MC into a metal box, you must bond the egc in the MC to the box. If you have an EGC coming from your feed side, that too must be bonded to the box. If you are using conduit as your EGC, the connector bonds it to the box.

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In other words does the wrap of MC cable count as a connection for the outlet box.
NO. The sheathing on MC cable is not considered to be an EGC.

Now, if you actually have AC cable instead of MC, then the sheath and the bonding wire within the sheath is considered to be an EGC as long as you use listed connectors.


and proby; I sure wish people would use the proper term. BX, as far as I know, was never an actual listed wiring method. Even when it had problems, I believe it was considered to be AC cable. I know what we use today is called AC cable. I believe that leads to a misunderstanding of the two different types of cable that look virtually the same externally (MC, AC)

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