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Regination 11-10-2012 01:44 PM

Box size for larger conductors
 
In my house I have to bring (3) 2/0's and (1) #6 into the back of a 4" deep box and then have them come out of the side of the box. I'll be using 2" PVC

What size box would I need? Would a 6" X 6" work or would I have to go wider?

Also, these wires are going straight thru, they are serving as a feeder for a panel. Would have have to ground the box if the wires aren't cut and spliced? If so, what's the best way to ground it? Can I just drill the box and bolt 2 lugs to it and then cut the #6 ground wire and run it into one lug and then come out of the other?

Thanks!

k_buz 11-10-2012 01:49 PM

Edit: 16"x16" Buy a PVC box. No grounding necessary.

Regination 11-10-2012 01:53 PM

Quote:

Originally Posted by k_buz (Post 1048908)
Edit: 16"x16" Buy a PVC box. No grounding necessary.

I was planning on putting this inside of the wall in the next stud bay over from the electrical panel.

Wow, 16" X 16" won't fit between the studs (14.5" space) :( I couldn't go smaller?

As for PVC, that sounds like a good idea. My only concern is that I know they make flush mount covers for metal boxes (in which the cover is larger than the box so it covers up the hole). I've never seen one for PVC. Do you know if they make them like that in PVC?

Regination 11-10-2012 02:01 PM

What if I used smaller PVC pipes to bring the conductors in and out of the box through? What is the smallest pipe I could bring (3) 2/0's and (1) #6 through?

k_buz 11-10-2012 02:01 PM

Quote:

Originally Posted by Regination (Post 1048913)
I was planning on putting this inside of the wall in the next stud bay over from the electrical panel.

Wow, 16" X 16" won't fit between the studs (14.5" space) :( I couldn't go smaller?

As for PVC, that sounds like a good idea. My only concern is that I know they make flush mount covers for metal boxes (in which the cover is larger than the box so it covers up the hole). I've never seen one for PVC. Do you know if they make them like that in PVC?

16"x16" is minimum. I do not know of metal JBoxes in these sizes that have flush mount covers. The covers come with the boxes and are the exact size of the box. You man be thinking of panels. Covers for panels come in flush and surface covers.

k_buz 11-10-2012 02:13 PM

Let's back up a bit here. I may have given you some bad advice. I saw you wrote straight thru and sized the box according to that. Now that I reread your OP, you are coming in the back of the box then out a side.

You need a minimum 12"x12"x4" box depending on where the conduit enters the back of the box, not a 16"x16" as I previously stated.

The code rule states...

Quote:

(2) Angle or U Pulls, or Splices. Where splices or where
angle or U pulls are made, the distance between each raceway
entry inside the box or conduit body and the opposite
wall of the box or conduit body shall not be less than six
times the metric designator (trade size) of the largest raceway
in a row.
This distance shall be increased for additional
entries by the amount of the sum of the diameters of all other
raceway entries in the same row on the same wall of the box.
Each row shall be calculated individually, and the single row
that provides the maximum distance shall be used.
Exception: Where a raceway or cable entry is in the wall
of a box or conduit body opposite a removable cover, the
distance from that wall to the cover shall be permitted to
comply with the distance required for one wire per terminal
in Table 312.6(A).
The distance between raceway entries enclosing the
same conductor shall not be less than six times the metric
designator (trade size) of the larger raceway.
When transposing cable size into raceway size in
314.28(A)(1) and (A)(2), the minimum metric designator
(trade size) raceway required for the number and size of
conductors in the cable shall be used.
So it is conceivable that you need a much larger box than a 12"x12", but the max depth will remain 4".

Regination 11-10-2012 02:15 PM

1 Attachment(s)
I've definitely seen metal box with oversized covers before. But that is the smallest concern I have right now, I'll probably just go with the PVC box like you mentioned.

I'm curious how you came up with the 16" X 16" size?

Using the following diagram and the applicable tables, I come up with 12"

Attachment 60309

I'm required to have a minimum of 3 1/2" of depth so the 4" box will work. And it seems like I would multiply the 2" pipe size by 6 to get 12" box width.

I appreciate your help with this :thumbsup:

Regination 11-10-2012 02:16 PM

Quote:

Originally Posted by k_buz (Post 1048931)
Let's back up a bit here. I may have given you some bad advice. I saw you wrote straight thru and sized the box according to that. Now that I reread your OP, you are coming in the back of the box then out a side.

You need a minimum 12"x12"x4" box, not a 16"x16" as I previously stated.

Great, that will work well for me and I am glad that I learned a little bit more about box sizing. Thanks :)

k_buz 11-10-2012 02:20 PM

I made some changes to the post you replied to, go back and reread it again. You might not be as happy as you were. Sorry for the roller coaster ride.

Regination 11-10-2012 02:37 PM

That last addition kinda sucks. If I was to put a nice big loop of conductors inside of the box, why does it matter how far away the entry points are?!?! :furious:


OK, I settled down a bit :laughing: So if I am using 2" pipe, and I come in through the back of the box all the way up near the top right side, and then come out the left side of the box all the way near the bottom, it should be at least 12" away. So I believe I am still good.

Basically, I have a meter pan outside with the main panel inside. I want to put an ATS right next to the meter pan and make that my main disconnect. So now I have to find a way to come out of the back of the ATS into the house and then over into the panel. I will be abandoning the nipple that currently exists between the meter pan and panel.

Maybe I would be better off forgetting about this box and just using a piece of SE cable? But then i have to worry about bend radius with that too :(

k_buz 11-10-2012 02:42 PM

SE cable to the panel is your best option, but I didn't suggest it because I didn't want to change your whole plan.

Regination 11-10-2012 02:51 PM

You're probably right, I just hope that the bending radius won't ruin it.

k_buz 11-10-2012 02:53 PM

It shouldn't.

Regination 11-10-2012 03:31 PM

Final question, I swear1

What would bend easier, copper 2/0-2/0-2/0-2 or aluminum 4/0-4/0-4/0-2/0?

k_buz 11-10-2012 03:33 PM

I have never used CU SE. I'm guess there is a SIGNIFICANT price difference between CU 2/0 vs AL 4/0. I'd go with AL.


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