# junction boxes for 4 gauge



## Bob Mariani (Dec 1, 2008)

An electrical supply will have many sizes of junction boxes. Not box stores! But you need to calculate the cubic inches as well as the size requirements of the box. Wires entering need a specific space from the location they exit. How many #4 wires in and out and total?


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## jamiedolan (Sep 2, 2008)

Homeedepot has 10x10x4's.
Jamie


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## Bob Mariani (Dec 1, 2008)

jamiedolan said:


> Homeedepot has 10x10x4's.
> Jamie


I guess you could just guess what size the code will require? since codes are only for sissies. :furious: But figure out what wires you are really dealing with and then we can help size the box.


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## frenchelectrican (Apr 12, 2006)

The larger box size will depending on following factors :

1) numbers of conductors

2) size of conductors 

3) type of cable or conduit 

4) depending on which way it will enter the junction box 

Those above item it will afffect the size of larger box 

Normally useally are 6X of the conduit or cable clamp size head up:: there is other factors may result even larger box.

Merci,Marc


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## J. V. (Jun 1, 2007)

jamiedolan said:


> Homeedepot has 10x10x4's.
> Jamie


Your right Jamie. They have 4x4x4, 6x6x4, 10x10x6 ect.... A bit expensive and they have concentric KO's which I do not like. For the DIY'er, they are perfect. No hole saw or KO punch required.

The electric supply will have a better selection and you can get a plain galvanized box for much less money if you are going to use this box inside. Also you will have to make your own holes. Most electricians prefer to make there own holes anyway.


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## 220/221 (Oct 9, 2007)

> What kind of junction boxes do you use for splicing 4 gauge wire?


Kind of depends on how many and what type.

A single #4 ground can be spliced without a box. I'd use at least 8x8 for a couple of #4 SE cables and I'd bring them in the same side of the box for a cleaner make up.


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## Bob Mariani (Dec 1, 2008)

Again, you should not just be guessing to box size. why not do it right when so many people here will help. If you use concentric KO's remember that the conduit if used is not sufficient for grounding unless you also use a grounding bushing or locknut. Just explain the number of wires you are trying to use and the type of wire and we can help.


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## 220/221 (Oct 9, 2007)

> remember that the conduit if used is not sufficient for grounding unless you also use a grounding bushing or locknut.


If it's over 250V to ground :whistling2:


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## bulk88 (Feb 2, 2009)

frenchelectrican said:


> The larger box size will depending on following factors :
> 
> 1) numbers of conductors


3 = line line neutral, all same size
-3 from mainpanel (upgradeable to 6 in future)
-3 to 1st subpanel
-3 to 2nd subpanel


> 2) size of conductors


all 4g, need 60 amps, 75C, derated for 85 amps* 4-6 in same conduit (*.8), and high temperature [boiler room/hot summers] (*.94)=63.92amps


> 3) type of cable or conduit


1.25" EMT from main panel
1" EMT to 1st panel
4/3 AC cable to 2nd panel


> 4) depending on which way it will enter the junction box


Either main panel wire and 1st subpanel enter on the east of the box, 2nd subpanel enters on west side of box, OR main panel wire enters on the south of the box, and 1st subpanel enters on north, 2nd subpanel enters on west of the box.

In junction boxes the 3 4g wires (per splice) are spliced with split bolts, fusing tape, covered with electrical tape. Currently the 2 subpanels will share a double pole 60 amp breaker, but in the future if I get a service upgrade, I might upgrade for each subpanel to be on its own 60 amp breaker, and increase number of/amps of the circuits in the sub panels.

Main Panel/service is 100 amps, 2 hot wires from 3 phase power, 208v hot to hot, not sure what the upgraded amperage would be (underground fed, my neighbor's detached 1 family house is fed from my basement before the meter), but I'm not doing a service upgrade myself.


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## frenchelectrican (Apr 12, 2006)

The minuim size I will suggest is 8X8X4 that is the smallest I will use but normally 10X10X6 work the best and also keep in your mind most split bolts are rated for two conductors if more than that you will have to get Polaris connectors I know they are little more expenisve but far much neater than use the splitbolt and quicker.

Use the metal box verison due you mention MC and EMT.

Merci,Marc


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