Can I use a hose clamp to ground a wire to EMT



What are the rules for how to attach a wire to an already grounded EMT conduit? Can I use stainless steel host clamp and tighten down?


I was installing a metal box for a light switch in our attic and had to terminate existing old NM cables that had no ground. Since there was no ground in the cable to ground the enclosure, a hot shorted to the box would be dangerous and would not pop the breaker.

As a temporary measure I used a metal hose clamp to run a bare #12 copper wire between the box ground screw and a nearby EMT conduit that was already grounded. The wire is never getting out, it is cinched under the clamp quite hard.

However, are there rules on what you are allowed to use fastened a wire to an EMT conduit for grounding? If so, then I can order a real ground clamp and go back up there, but if this is acceptable, then it would be convenient to leave it the way it is.

What I would have used if I had one:

2" grounding clamp

What I used (at least temporarily):

hose clamp

Best Answer

There's the Code answer, and the practical one:

Start from NEC 110.2:

The conductors and equipment required or permitted by this Code shall be acceptable only if approved.

Approved means listed and often means labeled. If the hose clamp has a listing number, it meets that bar.

Then add in NEC 110.8:

Only wiring methods recognized as suitable are included in this Code. The recognized methods of wiring shall be permitted to be installed in any type of building or occupancy, except as otherwise provided in this Code.

If you find a Code section that allows you to clamp the wire directly to EMT with a hose clamp, that would be an approved method.

Most likely your hose clamp is not listed, and I'm not familiar with any Code provision that allows use of a hose clamp for grounding.

Now, the practical answer: if it's genuinely solid this will probably be fine. Hopefully the clamp doesn't corrode, the wire against the conduit doesn't end up with high resistance due to the interaction between the metals, and if it does you never need the ground. That's a lot of items which need to line up.

Personally, it would lead me to pick up one of the right clamps the next time I'm getting other electrical supplies, then replace my hack with the right item. In fact, I did exactly this with a ground wire last year. I used a hose clamp on it to get things up and going, then bought a clamp like the one in your picture and swapped it out a few days later.

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