What size junction box to use

I am trying to figure out what size junction box I need to connect 6 awg wire.
I went to my local hardware store and the person there looked at me like I was an idiot, after talking to them for a min I realized they were the idiot...
Anyways, the biggest box they showed me was a 4x2 1/8 square box, which I know is just too small. Not enough room to join a 3x6 awg wires.
Basically I have hooked up my hot tub (which is outside) using armor cable for the outside run then when I ran out of that wire I bought another 30ft of indoor wire. Obviously the junction box where i am butt joining the wires is indoors. So basically I just need to know what size junction box I should be using.
Mighty Miindy
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snipped-for-privacy@gmail.com wrote:

I bet you could use a weather-proof circuit-breaker box -- like used for AC disconnect. They're less than $10.00.
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You have 3 wires in and 3 wires out. That is a total of 6 wires. My book is very out of date but it refers to NEC 370-6(b) which you might be able to reference.
My book states that each #6 wire requires 5 cubic inches of space. You need a box rated at 30 cubic inches. This site seems to confirm that information: http://www.tmsoftware.com/el96.htm#jbox
Just in case your math skills are rusty cubic inches is LxWxD.
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On 7 Jul 2006 07:53:12 -0700, snipped-for-privacy@gmail.com wrote:

a 30 sq/in box will work for six #6s. That is a 4x4x2 1/8. They also sell a 4 11/16 x 4 11/16 x 2 that will work. What is wrong is using AC cable for the spa (outside). It should be wire in pipe with an insulated ground.
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Why is using the AC wire outside wrong? I checked with the local codes and they said it was fine. It is a weather proof plasic shield with an armor ontop of that along with another plastic cover over the armor. I took a piece of it to the place where I got my electrical permit and they said it was fine...
Why do you say that it is wrong? I dont think I understand what you mean by a insulated ground.
The 4x4 2 1/8 box that I do have just doesnt seem to hold everything properly. By the time I butt join the cables the wire is extremly hard to bend and leave any extra in the box. But then again that just may be me being not strong enough to bend the wires, but still I would rather have a bigger box and give me more room to bend the wires specially after I butt join them and put the shrink sleave on the butt ends.
Mighty Miindy
snipped-for-privacy@aol.com wrote:

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AC wire normally doesn't have a plastic shield _over_ the armor. The outside is bare metal. Which doesn't work very good outdoors if it's steel.
Here, AC wire with a sheath over the armor is usually called TECK cable. _That's_ fine outdoors.


An electrician wouldn't ordinarily have problems with 3x #6 splices in a 4x4x2 j-box. You might want to use a utility box. These are usually simple rectangular boxes meant to be surface mounted with knockouts for cable clamps. Unlike j-boxes which have integral cable clamps, cover ears etc.
We have one somewhere around 4x4x6" holding a splice between 3 #4 copper and 3 #3 Al (100A feeder to a garage) plus the ground.
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Chris Lewis, Una confibula non set est
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On 7 Jul 2006 09:12:15 -0700, snipped-for-privacy@gmail.com wrote:

Sorry for any confusion "AC cable" is a specific wiring method. It sounds like you are talking about plastic coated "MC cable", which is OK if it has the green wire ground (most does)
"680.21 Motors. (A) Wiring Methods. (1) General. The branch circuits for pool-associated motors shall be installed in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or Type MC cable listed for the location. Other wiring methods and materials shall be permitted in specific locations or applications as covered in this section.
Any wiring method employed shall contain a copper equipment grounding conductor sized in accordance with 250.122 but not smaller than 12 AWG."
You should go for the deep 4 11/16 box or just put an extension ring on the one you have to increase it's depth if you are not comfortable with the fit. I agree 100% jamming wires like this into the box they say will fit may not be easy ... or safe. A two buck ring will give you some breathing room.
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