Subpanel/junction Box - Electrical - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical


Thread Tools Display Modes
Old 03-29-2011, 11:35 PM   #1
Join Date: Mar 2011
Posts: 1
Rewards Points: 10

subpanel/junction box

When do I use a subpanel vs j-box


smiledoc55 is offline   Reply With Quote
Old 03-30-2011, 02:40 AM   #2
Electrical Contractor
kbsparky's Avatar
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Rewards Points: 2,000

When you want to install more circuits/breakers.



Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 03-30-2011, 06:09 AM   #3
Join Date: Feb 2011
Location: SE Mass
Posts: 87
Rewards Points: 75

I assume you need to add circuits.
If there is room in the main panel for additional breakers, that should be considered first.
You need to factor labor and materials to get the additional circuits back to the main box.
A J-box will need EMT or PVC pipe from main panel to it, then circuits pulled,
(derating if there is more than 3 current-carrying conductors) all splices made up, neutrals, grounds, etc.
With a sub-panel, you'll have to run one heavier cable back to the main box,
but you'll use less branch-circuit wire,(as your 'homeruns' will be shorter).
The biggest mistake made with J-boxes is people put in ones that are to small,
they think a 4" box is enough, when it's far from it.
If you'll be branching out with many circuits, get a big one, 8 x 8, 10 x 10,etc.
I've seen horror-shows of boxes that look like a plate of spaghetti w/wires stuffed in, 1" long screws used to "pull" the cover down.
And the minute you dig-in...BZZZZT, now your stuck fixing the short-fall.
Usually the labor to install a box with individual wires is equal to adding a subpanel, or close.
Depends on how many circuits are involved, the distance, and the difficulty getting between locations.

Sorry if I ranted there...

Last edited by Do It Right; 03-30-2011 at 06:13 AM.
Do It Right is offline   Reply With Quote
Old 03-30-2011, 12:04 PM   #4
Join Date: Jun 2007
Posts: 3,772
Rewards Points: 204

If you have to ask that question, I highly encourage you to either learn alot more about this type of work or leave it to a pro.
J. V. is offline   Reply With Quote
The Following User Says Thank You to J. V. For This Useful Post:
Saturday Cowboy (03-30-2011)

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1