Butt Splicing allowed inside a junction box?


Old 10-13-14, 08:33 AM
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,465
Butt Splicing allowed inside a junction box?

I have a problem that perhaps butt splicing may help solve.

All metal junction boxes and EMT conduits. I have say three boxes.

BOX A(PANEL) ------> BOX B ------> BOX C

From BOX A to BOX B is about 40' and from BOX B to BOX C about 50'. BOX A and C are on walls, where BOX B is in the ceiling.

When I opened BOX C to do some rewiring, I noticed one #12 conductor is a bit short. It extends only like 3" into the box and the wire nut is a bit strained.

I then went to BOX B to look, and that conductor has some slack in BOX B. BOX A is the panel and the length there is barely enough.

This particular conductor is just passing through BOX B, really does not need to be spliced there, yes I know I can rerun a 90' long run from A to C and that's the best solution. However that seems to be a bit costly to just gain 4" or so of slack, not to mention I don't think I can pull just that one conductor out and refeed a new one, without having to pull out the rest of the conductors in the conduit.

So my question is, can I use one of these?


SolderGrip Heat-Shrink/Solder Multiple Wire Butt Splices
SolderGrip heat-shrinkable solder-type connectors and terminals are designed for electrical termination of multiple-wire combinations. They provide a reliable alternative to crimping, welding, or conventional twist-on-style closed-end connectors. Their unique combination of wire fixturing and controlled soldering technology provides dependable electrical termination.
  • Solder/heat-shrink multiple wire butt splices
  • For 14-12 wires
  • Temperature rating of insulating material 125o C (257o F)
  • Insulation rating of wire 75o (167o F)
  • Voltage rating 600 V
  • Copper solid/stranded wire
  • Shrink Ratio s:1
  • CRU US listed

Can I use one of these in BOX B, to provide a soldered butt splice connection, so that I can pull out more slack in BOX A and BOX C?

It seems this would solve my problem nicely. As the line is just passing through BOX B, it doesn't need any slack...or does it? May be the existence of a butt splice, any splice, requires say 6" of extension into BOX B so I can't rob B to pay A and C?
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Old 10-13-14, 08:38 AM
pcboss's Avatar
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Join Date: Jul 2002
Location: Maryland
Posts: 14,587
If the connector is rated for solid as you listed above you should be fine. I am not sure how you are going to solder if the wires are that short.

Ideal make a similar connector that is a push-in style or one of their regular push-ins could also work.
Old 10-13-14, 09:38 AM
Thread Starter
Join Date: Oct 2005
Location: Florida
Posts: 1,465
pcboss, I think I can disconnect everything in BOX A and C, pull back all six conductors for about 6 or so inches...in BOX A the panel, I think I might be able to just pull that single conductor by itself to give me some slack in BOX B. In any case I think I can create enough slack for this conductor to isolate it with enough distance to perform the butt splice with the heat gun. Once I am done, I will push everything back in place and hopefully in BOX A and C I gain enough free conductor.

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