two services
- Thread starter domnic
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
only if the one ground bar < 25 Ohms. otherwise you need two.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
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.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
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?
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?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Is it really two services? Two drops or laterals?
peter d
Senior Member
- Location
- New England
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.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Considering one is single phase and one is three phase, it's a safe bet there are two drops there.
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.
kwired
Electron manager
- Location
- NE Nebraska
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).Considering one is single phase and one is three phase, it's a safe bet there are two drops there.
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.
peter d
Senior Member
- Location
- New England
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.
This isn't my first rodeo.
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