seperate service transformers

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mannyb

Senior Member
Location
Florida
Occupation
Electrician
we have a cell tower with multiple meter loops coming from a single utility pole opposite cell site. our drawing shows a new service coming off new new transformer opposite side. This is what POCO said could be a no go

POCO reponse to new service.....The plan you sent shows a proposal to feed the new meter from a new transformer to be installed on the north side of the fire station. This might be possible, except that we believe the National Electrical Safety Code will not allow it for this reason. There would be multiple points of service on a single structure from widely separate sources, and on a metal structure. We do not believe this is acceptable.


i havent replied to email just yet but i do believe this is permitted 230.2 B 1 what do you guys think??
 
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mannyb

Senior Member
Location
Florida
Occupation
Electrician
REPOSTED

REPOSTED

REPOST I wasnt able to edit first draft. We have a cell tower with multiple meter loops coming from a utility transformer on one side of the cell site. our drawing shows a new service coming off separate new transformer opposite side.

POCO response to new service.....The plan you sent shows a proposal to feed the new meter from a new transformer to be installed on the north side of the fire station. This might be possible, except that we believe the National Electrical Safety Code will not allow it for this reason. There would be multiple points of service on a single structure from widely separate sources, and on a metal structure. We do not believe this is acceptable.


i havent replied to email just yet but i do believe this is permitted 230.2 B 1 what do you guys think??[/QUOTE]
 
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mannyb

Senior Member
Location
Florida
Occupation
Electrician
multi points of service

multi points of service

The NEC in my opinion permits multiple service to a single building provided certain rules. Our local POCO is referring to NESC as far as multple service points to a single metal structure. We have customer who has several cell phone carriers on a piece of land with seperate Hframes and meterloops for each carrier. The POCO claims this violates NESC and a more expensive alternative is the only way. It not expensive on their end its expensive to our customer on our end. ANY WHOO! anyone ever hear of such a thing? i believe NESC governs safety for utility providers just not familiar with NESC?
 
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GoldDigger

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Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
The only thing I can think of is that POCO is concerned about separate distribution Multiply Grounded Neutrals (MGNs) originating possibly from different substations becoming interconnected through customer wiring by virtue of both being bonded to the local GES.
In some cases this might result in objectionable current or even exposure to high stray voltages in the event of failures on their side.
The only way to alleviate this would be to have an isolation transformer on the POCO side to isolate the MGN from the customer bond point (acting as an SDS).
With one or more POCO sources from the same distribution line, multiple metering should be OK.
Very large sites with redundant feeds from multiple substations require substantial engineering on the POCO side.

Different isolated buildings on the same land should not pose any problems.

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