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Recently bought a house with a suspicious electrical setup running to a detached garage. Garage is about 70 feet from the main panel. Feeding the garage is 10/3 Romex with no ground wire on a 30amp breaker. The romex is fed to the garage from the roof of the house overhead. Inside the junction box in the garage is a mess - 10 gauge pigtailed with 10,12 and 14 garage wire feeding several outlets, lights and switches (see second picture).

Would love some advice on whether or not this is a safe enough setup. We have no need for 30amp power so I’m wondering if I can just change the breaker from 30a to 20a.

Also, concerned that there is no ground wire and how to remedy without installing a sub panel.

Thank in advance for any advice!

[junction box in garage1

overhead feed to garage

panel

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    Wait, is that weatherhead with the 3 separate wires the feeder to the garage? Are there actually 3 wires coming out of that weatherhead and is the metal pipe grounded? – Harper - Reinstate Monica Nov 11 '20 at 20:51
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    Do you really need 240v in your garage? You might be able to re-wire at each end, and use one of those hot wires as a ground (and marking it as a ground wire). If there's 14 gauge wire pig-tailed in, you'd have to replace the breaker with a single 15 amp breaker, not 20. – Steve Sether Nov 11 '20 at 20:55
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    @harper Yes that is the feeder to the garage with three wires coming in and out. The metal pipe is not grounded. Steve- I do not need 240v in the garage so that is what I’m thinking. You’re right if I do keep the 14 gauge wire, I’d go with a 15a breaker. Thank you both – Robert Nov 11 '20 at 21:11
  • First off: what is actually used for the overhead cable to the garage? Is that a prefab triplex, or...? – ThreePhaseEel Nov 12 '20 at 1:33
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First there are multiple code violations even if done in the 60’s when Romex or nmb did not have a ground.

Having 2 hot and a neutral was ok I believe until the 1999 code change. But the max breaker is 15 because of the 14 gauge wire. If the 14 gauge was removed a 20 amp breaker could be used but that was the max when built and still is today without a sub panel.

The switches and outlets for 120v are only listed for 20 amp circuits a 30 amp is a violation (even if a 15 amp receptacle or switch they can be used on a 20 amp circuit and be code compliant).

Could this be made safe? Yes, change the breaker to a 15 amp OR remove the 14 gauge wire and go to 20 amp. Install GFCI protection on both lines you have 2 120v 15 OR 20 amp circuits at that point and this would be safe and even code compliant.

What would it take to make it better? Meet today’s code? I would suggest a sub panel but then you would need A ground would have to be pulled from the service or on a point from that same panel to the garage. A ground electrode would need to be driven or other method of grounding electrode to the panel. Then you could leave the 30 amp breaker in the main, install a 20 amp breaker for the #12 and a 15 amp breaker for the #15. And that would pass (what you have should have been flagged on the home inspection for the reasons I mentioned).

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