600 amp main grounding

B

boblhead

Member
Location
New Hampshire
Occupation
Electrician
I have an old building being converted into5 apartments and one house panel. Meter bank fed from transformer, no disconnect except individual 100 amp unit disconnect’s, meter bank is mounted on pedestal then individual runs to trough on building.
The only grounding available for service is ground rods. I planned on#4 to ground rods but should I be using 250.122, 1awg copper
 
If the only grounding electrodes are rods, a #6 is all that is required but #4 is commonplace due to protection requirements.
No need whatsoever to go to #1.
 
boblhead said:
I have an old building being converted into5 apartments and one house panel. Meter bank fed from transformer, no disconnect except individual 100 amp unit disconnect’s, meter bank is mounted on pedestal then individual runs to trough on building.
The only grounding available for service is ground rods. I planned on#4 to ground rods but should I be using 250.122, 1awg copper
Click to expand...
Can you do that?
If the meter bank is on a pedestal. Would that not be supplying a detached structure (building ) with feeders if the meter bank has breakers in it. Then they would have to be grouped at the building.

If there is no breakers in The meter bank these would be service conductors. Again would they need to be grouped.

If service conductors they can not go through one unit to feed another.

I take it the house panel may be out side which would be main #1 or feeder disc #1.

I know that was not the question. Just curious.
 
Tulsa Electrician said:
Can you do that?
If the meter bank is on a pedestal. Would that not be supplying a detached structure (building ) with feeders if the meter bank has breakers in it. Then they would have to be grouped at the building.

If there is no breakers in The meter bank these would be service conductors. Again would they need to be grouped.

If service conductors they can not go through one unit to feed another.

I take it the house panel may be out side which would be main #1 or feeder disc #1.

I know that was not the question. Just curious.
Click to expand...
230.40 Exception permits each occupancy to have a set of service conductors. It is my opinion that each meter supplies an occupancy. 230.71(B) permits each set of service conductors permitted by 230.40 Exception 1 to have up to six disconnects.
There is nothing that requires the service disconnects for one set of service conductors to be grouped with the service conductors for any other set of service entrance conductors.
However each set of service disconnects would have to be located nearest the point of entrance of the service entrance conductors. That rule would likely be a problem for this application
 
boblhead said:
Meter bank fed from transformer, no disconnect except individual 100 amp unit disconnect’s, meter bank is mounted on pedestal then individual runs to trough on building
Click to expand...
Maybe describe what this means in a little more detail. Some seem to think there is problem here. I thought it sounded ok, but maybe some of us are missing a detail or so.

I took it to mean meter(s) on a pedestal.

Service disconnects on a trough on the building.

As mentioned each occupancy likely can have it's own service, but since there is less than six it sort of doesn't matter anyway if they are all grouped together - which I kind of assumed they were if coming off a trough.

If the disconnects are not on the building it can be a little more complicated. If not on building but very close to the building - NEC doesn't exactly say so but some AHJ's may allow that to be treated same as if it were on the building.
 
boblhead said:
I have an old building being converted into5 apartments and one house panel. Meter bank fed from transformer, no disconnect except individual 100 amp unit disconnect’s, meter bank is mounted on pedestal then individual runs to trough on building.
The only grounding available for service is ground rods. I planned on#4 to ground rods but should I be using 250.122, 1awg copper
Click to expand...
2023 NEC

250.66 (A)
A 6 Cu AWG is the correct size for any size service or voltage as long as it does not extend on to another type of electrode(s) that require a larger size.

T.250.122 is for selecting an EGC (equipment grounding conductor) of the wire type based on the rating of the conductor(s).
Not for a service.
See the caption of T.250.122 and the description found there in 250.122 in the left side of the table.

Thanks for reading
Comments accepted
TX+MASTER#4544
 
kwired said:
Maybe describe what this means in a little more detail. Some seem to think there is problem here. I thought it sounded ok, but maybe some of us are missing a detail or so.

I took it to mean meter(s) on a pedestal.

Service disconnects on a trough on the building.

.
Click to expand...


My comment was based on service disconnects built into the meter enclosure on the pedestal, feeders run to the building. But yeah, OP needs to clarify where the service disconnects are.
 
don_resqcapt19 said:
230.40 Exception permits each occupancy to have a set of service conductors. It is my opinion that each meter supplies an occupancy. 230.71(B) permits each set of service conductors permitted by 230.40 Exception 1 to have up to six disconnects.
There is nothing that requires the service disconnects for one set of service conductors to be grouped with the service conductors for any other set of service entrance conductors.
However each set of service disconnects would have to be located nearest the point of entrance of the service entrance conductors. That rule would likely be a problem for this
Click to expand...

kwired said:
Maybe describe what this means in a little more detail. Some seem to think there is problem here. I thought it sounded ok, but maybe some of us are missing a detail or so.

I took it to mean meter(s) on a pedestal.

Service disconnects on a trough on the building.

As mentioned each occupancy likely can have it's own service, but since there is less than six it sort of doesn't matter anyway if they are all grouped together - which I kind of assumed they were if coming off a trough.

If the disconnects are not on the building it can be a little more complicated. If not on building but very close to the building - NEC doesn't exactly say so but some AHJ's may allow that to be treated same as if it were on the building.
Click to expand...
Not on building, no available space, old existing building, no basement, I will be calling state inspector for a look
 
kwired said:
225.30(C)(1) for multiple occupancy building - 2023, but likely 2020 as well. Is preceded with 'by special permission'
Click to expand...
225.30(B) was the one I was thinking of, but that would require the disconnects at the second building to be grouped.

He might be better off with no service disconnects at the pedestal and just running service conductors over to each occupancy per 230.40 exception number one
 
So appreciate the input, although bank on pedestal has disco/meter for each unit, I will put additional disconnects grouped at building. Since redoing everything that was done would be costly.Pedestal is more than 50’, (80’)
 
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