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I installed a spa sub-panel on the exterior of my house. The inside wiring is NM-B 6AWG cable that goes to a junction box where it's spliced to 6AWG direct bury cable (the NM-B wire I had wasn't long enough, so it was cheaper to splice).

The splice was done with split bolts, wrapping 3M Temflex rubber splicing tape, then wrapped in electrical tape.

The inspector claimed that split bolts wrapped in tape are not rated for live connections and I would need to replace the split bolts with standard blue wire nuts.

Is the inspector wrong? To me, the wrench-tightened, rubber insulated splice would be more durable then a $0.50 wire nut.

isherwood
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Chris Thompson
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  • Are the split bolts used listed for use with 6AWG wire? – ThreePhaseEel Jan 19 '17 at 22:55
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    "To you" isn't really a factor; usability is decided by, as ThreePhaseEel says, the manufacturer listing the splice for certain uses, and a testing lab like UL or CSA certifying it. This is also informed by the voice of experience watching splices fail. – Harper - Reinstate Monica Jan 19 '17 at 23:01
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    The split bolts are rated for 6AWG and are UL listed. The Temflex is rated for 600v and also UL listed. The splice is for a 3 conductor, 240v circuit. – Chris Thompson Jan 20 '17 at 06:18
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    Are they listed for conductors rather than just grounds? You could push back on the inspector with those arguments. I suspect he's not against the split bolts so much as the tape, which makes it impossible for him to inspect. And he has every fair reason to want to inspect homeowner work more thoroughly. – Harper - Reinstate Monica Jan 20 '17 at 16:12

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If you are discontent with the quality of wire nuts, you can go to a proper splice block. These are my go-to for anything larger than 6 AWG.

enter image description here Source

The wires are inserted in the side, then they are tightened down from the top holes with hex keys to a specified torque. The holes where the hex keys go in are then capped. If the wires are near the largest size the block permits, there is nothing exposed at all. The quality of the connection is exceptional.

Harper - Reinstate Monica
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To answer your question, split-bolts properly insulated (as you've done) certainly ARE rated for "live" conductors. Ask your inspector to provide the code citation prohibiting them. For decades split-bolts were the go-to splice for larger conductors.

Speedy Petey
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    You do commercial so I'd like to ask. Do you ever even bother arguing with an inspector, so long as *what they say to do* isn't itself a code violation or outright wrong? – Mazura Jan 20 '17 at 02:38
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    @Mazura, I wouldn't argue with an inspector, but if they ask for something that is not required it generally costs me money. .... I'd simply ask *"Can you provide me the code section for this violation? I'd like to go over it so I don't make this mistake again."* It has worked for me in the past, they typically just say well, it's not a code requirement, but I'd like to see it. I guess I am lucky to not have asshole/incompetent inspectors in my area. – Speedy Petey Jan 20 '17 at 12:24
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Code inspector is right, but not for reasons you are arguing. Code inspector needs UL certification, and a $1 split bolt has very little UL certification. No manufacturer would pay $5K for cert, and $4K/year for certification renewal in order to sell you a $1 bolt. (There are some, but not approved or tested below ground for the same reason: no money in it)

However, a $3 splice, a rectangular block of aluminum, perhaps $6 with a heat shrink tube from HD would likely have the UL cert. You could squeeze a little nolox on it and tighten down with an allen wrench. A wire nut has the cert, but will not be happy in conduit when new wires need to pass through.

UL cert is awesome, but unfortunately multiplies the cost of some components which sell less. This is the same reason a tough plastic box can sell for $8, but an electrical plastic box will sell for $50. But you get something by paying more: if nationwide there is a problem with the accepted solution, you get recall knowledge.

Fredric Shope
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norman graham
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  • Split bolts are UL listed to UL486A/B just like other kinds of wire connectors, see the [cutsheet for this Ilsco split bolt](https://www.ilsco.com/Ilsco/CutSheetPDF?sku=IK-2-ILSM-ILS) for a representative example – ThreePhaseEel Mar 09 '23 at 04:38