Size of service entrance cable?

Discussion in 'Electrical Forum discussion & Blog' started by rdtompki, Dec 18, 2007.

  1. rdtompki

    rdtompki New Member

    Messages:
    115
    Location:
    Iowa
    Is there a standard gauge for residential (overhead) service entrance cable? Seems like the gauge would have to be the same as the utilities overhead wire. I'm going to call my utility tomorrow to verify.

    I don't know that it matters, but my breaker panel which is integral with the meter is 100 amps.

    Rick
  2. 480sparky

    480sparky In the Trades

    Messages:
    149
    If you are referring to the aerial wire that's between the pole and service entrance mast (commonly called "triplex"), power companies have their own rules to determine the size.
  3. rdtompki

    rdtompki New Member

    Messages:
    115
    Location:
    Iowa
    PG&E refers to this wiring as the "service entrance wiring" which extends from the connection with their overhead wiring to the meter. Looks like the gauge is a local jurisdiction or NEC issue. I'll look at the NEC tonight and call the inspector tomorrow to verify.

    Seems a bit strange that PG&E says "Weatherproof wire is not permitted in conduit" when this same wire is exposed from where it exits the service head to the connection with the utilites wire.

    Rick
  4. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    I always wondered why they don't extend the triplex down the riser and land it at the meter lugs.


    Here we must provide 2/0 copper (200 amp service) for them to attach their 1/0 aluminum. Maybe it gives the electrons an extra boost the last few feet???
  5. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    999
    Location:
    NY State, USA
    Or that one part is in free air and the other is in conduit. :rolleyes:
  6. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    POCO cable is completely the power company jurisdiction and is not based on the NECode.

    From power company jurisdiction (often the short length exposed at the weather head) to the lighting and appliance branch circuit panelboards in a dwelling the conductor size is controlled by Table 310.15(B)(6). From that panelboard to any subsequent circuits including subpanels the conductor size is controlled by Table 310.16 and subsequent.

    Table 310.15(B)(6) allows smaller conductors than Table 310.16. For example; 2/0 copper may be used for 200 Amp service conductors per Table 310.15(B)(6) but only to 175 Amps per Table 310.16.
  7. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Years back we used to use URD between the meter socket and out the weather head. But they stopped the practice when they realized the insulation wasn't UV resistant.

    It was faster and easier than service entrance cable.
  8. rdtompki

    rdtompki New Member

    Messages:
    115
    Location:
    Iowa
    Thanks, guys.

    I'm going to check the rating on my panel. It's got a 100 amp main installed, but if the panel is rated for 200 amp I may install service cable appropriate to that amperage (I understand the allowable 1 gauge de-rating) in case I ever want to upgrade the service. Would be a bit easier than going through PG&E again.

    PG&E was actually very helpful. The guy I spoke with advised using Sch80 conduit, for example, as being easier than having to put a PVC cover on metal conduit (required in our jurisdiction). All my concern about using the exsting wiring was moot since I was going to have to upgrade from the weatherhead on down.

    Rick
  9. 480sparky

    480sparky In the Trades

    Messages:
    149
    You will also need to make sure the wire size is capable of handling 200amps, as well as the meter socket.

    It would not make sense to install 2" conduit/weatherhead/hub, a 200a meter socket and 2/0 wire only to put in a 100a panel. My guess is you will need an entire service change.
  10. kd

    kd New Member

    Messages:
    207
    Residential sizes: #4 copper ( or #2 Alum.) for 100 amp, 2/0 copper (or 4/0 Alum.)for 200 amp. But some AHJs have outlawed Aluminum or want one size larger wire, so check with the local insp first.
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,561
    Location:
    North Carolina
    Where? .
  12. rdtompki

    rdtompki New Member

    Messages:
    115
    Location:
    Iowa
    I haven't installed the panel yet. I'm thinking that the cost of a 200 amp panel and 15' of appropriate-gauge service cable is small provided the cable that PG&E brings to my pole is adequate gauge. Might as well go with the 200 amp. I'll verify the required gauge with my inspector.

    Rick
  13. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    HD sell a 3-wire 4/0 aluminum cable that is suitable for 200 Amp service entrance. It is a lot larger than the #2 aluminum that the POCO conntected to it when I installed it. You can put that 4/0 into a 2" conduit.

    If aluminum is satisfactory for the POCO then it certainly should be OK for your inside work. They didn't use any antioxodant compound when it was installed and the connections are not covered with waterproof insulation.

    A 200 Amp Load Center and a 200 Amp meter socket may have maximum size of 4/0 so you wouldn't be able to go larger.
  14. kd

    kd New Member

    Messages:
    207
    A few years ago Petaluma city outlawed installation all Alum wire, residential and industrial, but it is approved now. I think it was Newport Beach that wanted me to use #2 Cu instead of the NEC #4...many years ago. The point is check it out- whether upgraded or downgraded-local rules rule! I know the Code says you can only upgrade...but ...it is being done.
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