Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
For a source of a separately derived system that is located outside the building or structure, a grounding electrode connection to one or more grounding electrodes shall be made 250.30A
My grounding book says the system bonding jumper is to be located at or near the same point of where the grounding electrode conductor connection is made to comply with 250.30 A 5
HOWEVER
The company I work for has a substation feeding 4,800 volts via power poles. Apparently the company owns the poles, lines and final pole mounted transformer which steps voltage down to usable 120/240
At the automotive repair shop within the surface of the mine I’m working at has the final pole mounted over head transformer feeding overhead to weather-head to inside first disconnect/ single phase distribution panel. (Ground strap type neutral bus to ground bus bonded via metal bar)
A year ago I installed a system bonding jumper
From the neutral bus to the panel cabinet sized per 250.102C
I have read that the transformer neutral cannot be bonded at this point of first disconnection from the building for separately derived systems but must be at the outdoor transformer or both outdoor location and inside distribution panel only if a parallel path for neutral current is not created
I also do not know if a system bonding jumper was installed at outdoor transformer and I assume the system bonding jumper could be installed at both the transformer and the building first disconnect/ distribution panel using NEC exemption if no EGC was ran with the supply conductors to panel and neutral conductor was also serving as EGC
Every panel inside a building I’ve seen has had either a system bonding jumper or main bonding jumper installed at the first disconnect / transmission beside house or building first distribution panel.
It has been very confusing where to add or remove system bonding jumpers. Thoughts?
My grounding book says the system bonding jumper is to be located at or near the same point of where the grounding electrode conductor connection is made to comply with 250.30 A 5
HOWEVER
The company I work for has a substation feeding 4,800 volts via power poles. Apparently the company owns the poles, lines and final pole mounted transformer which steps voltage down to usable 120/240
At the automotive repair shop within the surface of the mine I’m working at has the final pole mounted over head transformer feeding overhead to weather-head to inside first disconnect/ single phase distribution panel. (Ground strap type neutral bus to ground bus bonded via metal bar)
A year ago I installed a system bonding jumper
From the neutral bus to the panel cabinet sized per 250.102C
I have read that the transformer neutral cannot be bonded at this point of first disconnection from the building for separately derived systems but must be at the outdoor transformer or both outdoor location and inside distribution panel only if a parallel path for neutral current is not created
I also do not know if a system bonding jumper was installed at outdoor transformer and I assume the system bonding jumper could be installed at both the transformer and the building first disconnect/ distribution panel using NEC exemption if no EGC was ran with the supply conductors to panel and neutral conductor was also serving as EGC
Every panel inside a building I’ve seen has had either a system bonding jumper or main bonding jumper installed at the first disconnect / transmission beside house or building first distribution panel.
It has been very confusing where to add or remove system bonding jumpers. Thoughts?
