Sub Panel Amperage Limit?

B

behindpropellers

Member
Location
NE Ohio
Occupation
Mechanical Engineer
Hello,

We have a 15KVA transformer that was installed for a 200A service. It previously had a 100A service that was installed directly to the panel in the building which was too small. I had an electrician install a sub-panel adjacent to the transformer and we ran the branches off of that. I asked him to install 200A service into the building.

After asking for the 200A service I was out at the jobsite a few days later and he had installed a 125A service.

Is there a technical reason to why they did not do what I asked them to do?

Other issues I am having with this contractor:

1. Main leg into panel was not torqued down.
2. Loose grounds in job box next to receptacle.
3. Ground rod was sticking out of the ground (hazard). I pounded it down and found the ground clamp was loose.
4. Electrician didn't tell me I needed a EE PE to sign off service changes prior to starting the job.
5. Panel installed has a manufacturing defect.

I'm frustrated that I hired an "expert" and I am now reading regulations to find out what they messed up.

Tim

PS - The conduit connecting panels is 2" PVC. 1/0 ALU conductors with a #4 AL ground.
 
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Your description leaves a lot to be desired however it might be worth noting the output of a 15kva transformer would be more in the 75 amp range and, although it might not be a violation to feed a 200 amp panel (dependent on primary protection), a smaller panel might be more logical which lklely explains why the electrician wanted a PE or EE involved.
Obviously there are several workmanship issues that need addressing
 
augie47 said:
Your description leaves a lot to be desired however it might be worth noting the output of a 15kva transformer would be more in the 75 amp range and, although it might not be a violation to feed a 200 amp panel (dependent on primary protection), a smaller panel might be more logical which lklely explains why the electrician wanted a PE or EE involved.
Obviously there are several workmanship issues that need addressing
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Thanks. The electrician did not get a PE involved, they just did the work. They inspector asked so I'm the one getting the PE involved.

Pretty frustrated with the whole thing.

Tim
 
behindpropellers said:
Rob,

Electric company transformer. 7.2KV/12.5KV.
Click to expand...
So I'm confused. Why does the size of the utility transformer matter? If you've upgraded from a 100 amp service to a 200 amp service it's up to the POCO to decide if the transformer is adequate and should have no bearing on what your electrician installed. It sounds like your issue is solely with your sparky that you're unhappy with.
 
infinity said:
So I'm confused. Why does the size of the utility transformer matter? If you've upgraded from a 100 amp service to a 200 amp service it's up to the POCO to decide if the transformer is adequate and should have no bearing on what your electrician installed. It sounds like your issue is solely with your sparky that you're unhappy with.
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According to the building inspector it matters.
 
Service transformer sizing and protection is the responsibility of the power company. The NEC and the building inspector have no control over them.

You are allowed to put in what ever size main breaker you want to, as long as you advise the power company.

If the meter socket and service were supposed to be upgraded to 200A, per job specs, your EC should have done so. No PE required. If the socket and conductors were not upgraded, 125A may be your maximum size.
 
After some digging:

The meter/breaker combo (exterior by our transformer) (SC2040M200C) has a branch breaker rating of 100A. My electrician installed a 125A breaker and 1/0 wire to my main panel.

Apparently the previous PN of this panel accommodated a 200A branch circuit and breaker.

I can't find a meter base/main breaker that is rated at 200A with a branch capacity of 200A. Any alternatives?

Tim
 
behindpropellers said:
After some digging:

The meter/breaker combo (exterior by our transformer) (SC2040M200C) has a branch breaker rating of 100A. My electrician installed a 125A breaker and 1/0 wire to my main panel.

Apparently the previous PN of this panel accommodated a 200A branch circuit and breaker.

I can't find a meter base/main breaker that is rated at 200A with a branch capacity of 200A. Any alternatives?

Tim
Click to expand...
Still not all that clear when you say "by our transformer" as to whether this is a utility transformer or not.

Utilities often have small transformers relative to the sum of all the main breakers it may end up supplying. They have no issue with overloading them to some extent as long as it is not for an extended time, but most those are not loaded all that much very often. I also see a lot of 200 amp services, particularly to dwellings that only have #2 or even # 4 aluminum service drop run to them. The load just isn't there and POCO isn't going to upgrade the drop until there is enough load to be worth updating it in their eyes. This is all ahead of the "service point" and NEC does not apply to it. POCO can sort of do whatever they wish with it as long as it will deliver proper voltage within certain tolerance level.
 
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