Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I ran a new 240 volt circuit to operate some motorized equipment. The equipment has a 3 prong grounded 240 volt plug. My source however doesn't have a grounding strip. Would it be better to not connect the ground wire to anything on both ends.

My source is a dry transformer with a neutral but the neutral is not grounded. The building is a mower/ maintenance shed for a golf course built in the early 60's. The source to the building from the utility is 277y/480 volts mostly to run the irrigation pump. I think the building was added as an afterthought, therefore the dry transformer was added to provide power for outlets in the building. Two 480 legs and 1 supposed neutral provide power to the high side of the dry transformer. When I arrived on the scene, I discovered that the neutral is not used and is just floating. The secondary coils were paralleled to provide 120 volts only to the entire building. I since then have successfully split the coils and now have 120/240 to the whole building. So in answer to the question on grounding, I don't know if the main breaker at the meter has a good ground for the entire building or not because it is locked up(key issue?). At any rate, like I said the neutral on the secondary side of the dry transformer is not grounded and all individual 120 circuits going out from this panel have a hot leg and neutral only -no ground wires.

share|improve this question
What is your source, and why doesn't it have a ground? Are you saying you don't have a grounded conductor (neutral), or a grounding conductor (equipment ground)? –  Tester101 Dec 23 '12 at 13:24
Where in the world is Carmen San Diego? Planetary location tells us what Electrical Code you might be under. Grounding is usually a good idea so a short to the motor housing doesn't kill the person who accidentally bridges it to ground through their body. –  Fiasco Labs Dec 23 '12 at 18:40
@larry - please consider registering your account. That way you'll be able to edit your question and post comments –  ChrisF Dec 24 '12 at 22:00
You should seriously consider retrofitting a proper grounding system to the service entrance for the building. All new work can then be equipment grounded. Where feasible, existing circuits can have grounding added. It's the right thing to do. –  bcworkz Dec 25 '12 at 1:36
add comment

2 Answers

Yes I highly recommend grounding, or any hot wire to a metal casing will you use as its ground- not cool. Not cool at all! In fact it will probably be just the opposite.

share|improve this answer
add comment

If you're in the United States, a grounding conductor is defiantly required for all new work.

If the system was installed before grounding was required, you're not required to update the system and add grounding when the code changes. However, if you add anything to the system after the code change, you must do so in a code compliant manner. This might mean bringing the entire system up to current codes, or at least enough of it to allow the new work to be code compliant.

You might be able to simply install a proper grounding electrode at the building, and use that to ground the circuits on the secondary side of the transformer. You'll have to contact your local government to find out if that's adequate, and also to have the work inspected to insure it's done properly.

share|improve this answer
Given that he has a transformer, I would guess a ground is only needed for the secondary side of the transformer. Does anyone know? –  Philip Ngai Apr 9 at 6:14
add comment

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.