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Thread: two services

  1. #1
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    two services

    I have two services 0ne 120/240 volt and one 3 phase 240 volt side by side ( 2') from each other. can I use one ground rod for the two.

  2. #2
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    Quote Originally Posted by domnic View Post
    I have two services 0ne 120/240 volt and one 3 phase 240 volt side by side ( 2') from each other. can I use one ground rod for the two.
    only if the one ground bar < 25 Ohms. otherwise you need two.
    Bob

  3. #3
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    2 rods can service either one service or both but as stated above 2 rods are generally needed at least 6' apart, unless you can show 25 ohms on one rod.
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  4. #4
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    think about this.

    if I have either one or two services like this, and ground rods are the only GE, to create my GES I would need to put in two of them 6 feet apart and bond them together with a conductor that never has to be larger than #6, but can be as small as whatever table 250.66 allows.

    i could then attach a #6 (or a smaller conductor if allowed by T250.66) to each rod and go to the separate services with separate conductors.

    however if I came off one rod and went to both services with the same conductor, I would need to make it a 3/0 with taps to each service sized in accordance with 250.66.

    what logic is there in that?
    Bob

  5. #5
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    Quote Originally Posted by domnic View Post
    I have two services 0ne 120/240 volt and one 3 phase 240 volt side by side ( 2') from each other. can I use one ground rod for the two.
    Is it really two services? Two drops or laterals?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  6. #6
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    Quote Originally Posted by electrofelon View Post
    Is it really two services? Two drops or laterals?
    Considering one is single phase and one is three phase, it's a safe bet there are two drops there. That being said, the poco may have tapped the 120/240 single phase service from the 240 volt delta service with a center tap, but I've never seen an odd duck like that.

  7. #7
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    Quote Originally Posted by peter d View Post
    Considering one is single phase and one is three phase, it's a safe bet there are two drops there. That being said, the poco may have tapped the 120/240 single phase service from the 240 volt delta service with a center tap, but I've never seen an odd duck like that.
    Quite a few times I have seen all sorts of permutations with high leg services. Sometimes multi meter set up with some getting the high leg and some not. Personally, I would find it odd for the utility to supply another drop for this arrangement.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  8. #8
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    Quote Originally Posted by peter d View Post
    Considering one is single phase and one is three phase, it's a safe bet there are two drops there. That being said, the poco may have tapped the 120/240 single phase service from the 240 volt delta service with a center tap, but I've never seen an odd duck like that.
    They are all over around here, lots of 120/240 single phase services supplied by a 120/240 three phase source, with that one customer in the five supplied that utilizes three phase (or something of that nature).

    If up to six sets of conductors run from a single source to up to six separate disconnecting means (may be more then six individual wires altogether when considering possible parallel conductors) it is considered one service. 120/240 volt single phase and 120/240 three phase both originating at same source is still only one service IMO. Sure you have different number of phases associated with one, but they are still a part of same system.

    120/240 single phase and 208/120 three phase by nature have to come from separate sources so if you had that for incoming it would be two services.
    I live for today, I'm just a day behind.

  9. #9
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    Quote Originally Posted by kwired View Post
    They are all over around here, lots of 120/240 single phase services supplied by a 120/240 three phase source, with that one customer in the five supplied that utilizes three phase (or something of that nature).

    If up to six sets of conductors run from a single source to up to six separate disconnecting means (may be more then six individual wires altogether when considering possible parallel conductors) it is considered one service. 120/240 volt single phase and 120/240 three phase both originating at same source is still only one service IMO. Sure you have different number of phases associated with one, but they are still a part of same system.
    Understood. My comment was based on local utility practice which would not do what your describe. It's actually almost moot these days since delta services are rare and the poco that serves my area does not offer delta service anymore, and they jump at the opportunity to disconnect them from their system and upgrade to wye.

    120/240 single phase and 208/120 three phase by nature have to come from separate sources so if you had that for incoming it would be two services.
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