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Old 09-22-2009, 02:31 AM   #1
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Default 3 wire feeder was installed to detached garage need input

First let me tell you what im doing on this job. Lady called and said she has no lights in the garage, pond pump outlet doesn't work, and shed light doesn't work. She also said she felt a light shock touching the aluminum siding on the garage.


So i go in the garage its a complete nightmare! Romex everywhere, disconnects everywhere, receps all over the place, switches ect...

Most of it was done ofcorse by the home owner

Ok so here is what layout is in the garage... You have the 3 wire feeders coming underneath the driveway and up in the corner of the garage into a 50 amp Murray circuit breaker disconnect. The load goes across the garage feeding another 30 amp murray breaker disconnect that feeds a recep for a welder. Also off of the load it feeds an OLD name? fused disconnect next to it. When i opened the fused disconnect i seen lots of neutrals wire nutted together with the grounds. From this disconnect it feeds a **** load of receps and switches all over the garage. It also feeds a switch that controls the pond gfi it transitions to UF at the switch.

Now the pond and shed are like 10 feet away from the garage. The shed is aluminum and the garage has aluminum siding.

There is a brand new black top driveway that seperates the shed,garage, and pond from the front house about 15 feet away.

I plan on putting a new subpanel in the garage and eliminating all the old disconnects and starting from scratch. As far as bonding, grounding what are your thoughts?

p.s. phone line was run in the conduit(pvc) with the feeders. Not sure if i should do this like a new service bond the ground with neutral in the panel and drive a ground rod?


Last edited by pawirenut; 09-22-2009 at 03:07 AM.
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Old 09-22-2009, 04:24 AM   #2
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Are there any 240 Volt loads (welder still in use?)?

I would rewire that feeder for 120 Volt operation only, making one line the hot, one a neutral, and one the EGC.

Otherwise, be prepared to get out a mole machine, and replace the whole feeder with a 4-conductor.

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Old 09-22-2009, 04:27 AM   #3
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Have u read NEC 250.32?
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Old 09-22-2009, 12:45 PM   #4
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Quote:
Originally Posted by Magnettica View Post
Have u read NEC 250.32?
About isolating the neutral from the EGC? That would work if i had a 4 wire feeder but i dont.

Basically the homeowner only wants lights in the garage to pull her truck in. She's 70 years old and her husband is in a wheel chair so he no longer is in the garage using welders and stuff she said.

I was going to install 4 porcelan pull chain lights operated by a switch. She doesn't want fluorescents. Its an old barn style garage with the sliding barn door.
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Old 09-22-2009, 12:54 PM   #5
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If you are putting in just four lights, this sounds like one
branch circuit, and 250.32 Exception says a grounding
electrode is not required. 225.39 allows a snap switch
for the disconnect, so it sounds like you would be done
with one switch and taking out all the other junk.
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Old 09-22-2009, 12:58 PM   #6
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Quote:
Originally Posted by rexowner View Post
If you are putting in just four lights, this sounds like one
branch circuit, and 250.32 Exception says a grounding
electrode is not required. 225.39 allows a snap switch
for the disconnect, so it sounds like you would be done
with one switch and taking out all the other junk.
Yes but their is a 20 amp shed circuit, and another cuircuit for the pond gfi coming from the garage. Like i said where the 3 wire feed comes in the garage it goes right into a 50 amp breaker disconnect then 3 other disconnects downstream from that.
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Old 09-22-2009, 02:07 PM   #7
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Ok what i've been reading is that as long as their isn't any metallic paths between the house and the garage a 3 wire feeder is ok. There isn't any metallic paths.

So im going to install the subpanel and bond the neurals/grounds together and drive a ground rod and call it a day.
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Old 09-22-2009, 03:38 PM   #8
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Didn't quite understand the termonology but it sounds a bit of a dogs dinner!! I would be inclined to start again.
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Old 09-23-2009, 01:53 PM   #9
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Quote:
Originally Posted by pawirenut View Post
Ok what i've been reading is that as long as their isn't any metallic paths between the house and the garage a 3 wire feeder is ok. There isn't any metallic paths.

So im going to install the subpanel and bond the neurals/grounds together and drive a ground rod and call it a day.
Yes. Do as you say. This was legal until the 2008 code was introduced. Even though I always considered it a personal violation. Just would not pull a three wire feeder to an unattached structure. I would drive two rods if the AHJ is involved.
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Old 09-23-2009, 05:30 PM   #10
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I don't know that I would ground the neutral at the garage . But I would bond the panel box locally with a ground rod..
The neutral should only be grounded at incoming main service to the property.
Or am I wrong?
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Old 09-24-2009, 02:22 PM   #11
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Quote:
Originally Posted by Toronto Sparky View Post
I don't know that I would ground the neutral at the garage . But I would bond the panel box locally with a ground rod..
The neutral should only be grounded at incoming main service to the property.
Or am I wrong?
In most every case you are right. But not in this case.
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Old 09-24-2009, 10:13 PM   #12
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In this case the 3 wire is existing so you can use it as is.Bond neutral and ground. and drive ground rod.
If 4 wire is use isolate nuetral and still drive a ground rod.
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Old 09-24-2009, 11:34 PM   #13
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Quote:
Originally Posted by John Valdes View Post
In most every case you are right. But not in this case.
My concern would be if the conductors were in a metal raceway or were encircled with steel (IE. Rebar) But I guess being that the amperage is low that would not be a concern.

Or possibly of a ground loop problem if any computerized equipment were to be used.
I know if a crt monitor is plugged into a receptacle that has a stray ground in contact with it's neutral will cause the monitor to have interference lines on it.
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Old 09-25-2009, 07:41 AM   #14
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The three-wire feeder was legal until the 2008 Code. The problem is the phone line. Even when a 3-wire was legal, it wasn't legal IF there were other metallic paths back to the house. The include water lines or phone and cable lines. There is nothing you can do with the existing that will make it compliant with any recent codes, except maybe turn it into a 120 V feeder.

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