I have a situation where the power companies transformer is about 300 ft from the panel we are feeding. Due to wall space problems the meter is being placed by the trans along with a 200 amp main breaker . The panel at the building now becomes a sub panel. So my question is , do i have to install 2 ground rods at the main panel and no gec at the sub panel. There is no water in the new building,but there is a concrete enclosed electrode allready installed?
service gec
- Thread starter m2oliva
- Start date
- Status
- Location
- Massachusetts
Re: service gec
Bond only at the transformer, install grounding electrodes at both locations.
Bond only at the transformer, install grounding electrodes at both locations.
- Location
- Illinois
- Occupation
- retired electrician
Re: service gec
What type of raceway is being used between the meter disconnect and the building? Are you installing an EGC with the feeder? No matter what, you need a grounding electrode system at both the building and meter locations?
Don
What type of raceway is being used between the meter disconnect and the building? Are you installing an EGC with the feeder? No matter what, you need a grounding electrode system at both the building and meter locations?
Don
- Location
- Massachusetts
Re: service gec
he was installing one. :roll:
Bob
Good question, I went ahead and assumed
he was installing one. :roll: Bob
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: service gec
Here goes:
2/0 copper ungrounded feeder circuit with 6 AWG EGC at 300'. Total resistance of circuit conductors is 0.1764 Ohms. Maximum line to ground voltage: 120V. 120/0.1764= 680A
Will 680 Amps safely and quickly initiate a 200 breaker?
I agree that a full sized fault clearing conductor (such as the nuetral) will do a better job (2,068Amps), but will the above scenario not work?
I'm not going to yell, but I will do some math, will all values from the NEC [310.15(B)(6)], 310.16, 250.122, table 8 of chapter 9.
Here goes:
2/0 copper ungrounded feeder circuit with 6 AWG EGC at 300'. Total resistance of circuit conductors is 0.1764 Ohms. Maximum line to ground voltage: 120V. 120/0.1764= 680A
Will 680 Amps safely and quickly initiate a 200 breaker?
I agree that a full sized fault clearing conductor (such as the nuetral) will do a better job (2,068Amps), but will the above scenario not work?
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: service gec
In the meantime, enjoy this inverse time curve.
In the meantime, enjoy this inverse time curve.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: service gec
"Is two posts w /some type of pressure treated wood between acceptable?" This question can only be answered by the POCO. Where I am, we can't mount a meter on a pressure treated post, it has to be metal strut, with a concrete pad in front.
I always liked using 10 ft PT posts, 6x6, that gives you 5 ft in the ground, 3 feet below the bottom of the ditch, so it stands up while the service is being installed. Now its strut and concrete, takes more time to install, not always better. But the POCO has probably seen meters installed on 2x4 that fall over..
"Is two posts w /some type of pressure treated wood between acceptable?" This question can only be answered by the POCO. Where I am, we can't mount a meter on a pressure treated post, it has to be metal strut, with a concrete pad in front.
I always liked using 10 ft PT posts, 6x6, that gives you 5 ft in the ground, 3 feet below the bottom of the ditch, so it stands up while the service is being installed. Now its strut and concrete, takes more time to install, not always better. But the POCO has probably seen meters installed on 2x4 that fall over..
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: service gec
What do you think Bennie?
What do you think Bennie?
- Status