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Thread: Replacing old sub panel 1950's

  1. #1

    Question Replacing old sub panel 1950's

    Hello, In our Michigan cottage, I had the fuses upgraded to 100 amp breaker service. There is a fused subpanel upstairs that feeds the 2nd half of the house
    The wire feed is entance cable 3 wire. The red & black and a bare metal as I remember.
    With a new subpanel, will I simply be copying the wire setup as currently there?
    The red & black load and 3rd wire to neutral? There is no ground wire.
    Thank you.

  2. #2
    Electrical Contractor/Instructor jwelectric's Avatar
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    The bare wire is the equipment ground and you have no neutral.

  3. #3
    Plumber Cass's Avatar
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    The "bare" wire ...is it stranded wire...maybe twisted together? If so it is most likely the neutral. If it is solid bare copper it is a ground wire.

    The sub should have a neutral and isolated ground and should not be bonded.
    Last edited by Cass; 08-07-2008 at 07:12 AM.

  4. #4
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Cass View Post
    The "bare" wire ...is it stranded wire...maybe twisted together? If so it is most likely the neutral. If it is solid bare copper it is a ground wire.
    This is incorrect information.
    Any conductor that is being used as a neutral or the grounded conductor on the load side of the service is required to be insulated.
    If the conductor is bare no matter if it is solid stranded or a wrapped conductor such as in SE cable on the load side of the service and it is uninsulated it is the equipment grounding conductor.
    The only place that a bare wire can be used as the neutral on the load side of the service and be unisulated is found in 250.140 Exception and then it must originate in the service equipment and land at a range or dryer receptacle.

    Quote Originally Posted by Cass View Post
    The "bare" wire ...is it stranded wire...maybe The sub should have a neutral and isolated ground and should not be bonded.
    The subpanel is required to have an insulated neutral and an equipment grounding conductor. Any thing less is dangerous.

  5. #5

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    With a new subpanel, will I simply be copying the wire setup as currently there?
    They did things differently in the olden days. Now a seperate neutral and ground are required. If you copy the current configuration, everything will work the same but will not be code compliant.

  6. #6

    Default 1950's sub panel upgrade

    Ok, as I remember, it was a few months ago I was there, there is the red, black and a 3rd wire. they all are insulated. The red, black connect at the top of this panel, the twisted 3rd wire is attatched at the bottom, I'm assuming neutral.

    Updating to a new panel, the red & black would attatch as load, in their separate locations and the 3rd wire connected to neutral bar. as neutral, with NO ground strap or connection between the neutral bar and any terminal for grounding.
    Since there are no grouned circuits in the home, a gfci at the first outlet on each line would provide the same protection?
    Thanks again.

  7. #7

    Default 1950's sup panel 2

    I missed asking this in my last post; after reading further.
    The 3rd wire is the isolated neutral, how would I get a dedicated ground? Run a ground from the panel, down the second floor wall to a double grounding pipe?

    I'd like to stay as close to code for a reason; it's good sense and safer.

  8. #8
    Electrical Contractor/Instructor jwelectric's Avatar
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    Sounds like you are in way over your head and the advice you are getting here is really bad advice.

    You need to hire someone that knows what is going on before you end up hurt or even worse.

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  10. #10
    Electrical Contractor/Instructor jwelectric's Avatar
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    Cass
    This is a fairly good site but I see some violations in this installation

  11. #11

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    If you use the existing 3 wire feed and isolate the neutral, your panel will not be grounded. This is a very bad idea.

    Can you run a seperate ground back to the service for your ground?

    It would serve the purpose but the legality will come into question. I've seen it passed and I've seen it failed. It's certainly not going to kill anyone.

    What we generally do is run a new 4 wire feed or run new circuits from the new service to the old sub panel location, take out the guts and use it as a JB.

    It will be easier to use GFCI breakers on all your circuits to protect the ungrounded circuits.
    Last edited by Alectrician; 08-09-2008 at 09:01 AM.

  12. #12

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    Quote Originally Posted by jwelectric View Post
    Sounds like you are in way over your head and the advice you are getting here is really bad advice.

    You need to hire someone that knows what is going on before you end up hurt or even worse.
    Thats some sound advice Mike. I am all for DIY but people need to learn thier limits. Its a lot easier to do it here on the internet then the hard way (when somebody gets hurt)

    Lou

  13. #13

    Default 50's subpanel.

    Ok, then to run a new, 4wire se cable to subpanel, the length of 50 ft.
    what guage will we be looking at?
    I can run the cable, have it connected and inspected, or at least inspected
    The sub panel breaker is 60 amp.

  14. #14

    Default

    For 60A. #6 NM will have 3 6's (black, red, white) and #10 (bare) ground.

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