POCO Transformer Sizing - Electrician Talk - Professional Electrical Contractors Forum

Cletis · 09-14-2011, 05:18 PM

What factors do the engineers from POCO use to determine if residents need new transformer?

Ex. I have a house we put a 25kva on demand heater in and when it kicks in the whole house dims. Turns out that 7 houses are on a 50kva transformer. The tech said he will talk to his boss to see if they can upsize it.

Magnettica · 09-14-2011, 05:26 PM

Quote:

Originally Posted by Cletis

What factors do the engineers from POCO use to determine if residents need new transformer?

Ex. I have a house we put a 25kva on demand heater in and when it kicks in the whole house dims. Turns out that 7 houses are on a 50kva transformer. The tech said he will talk to his boss to see if they can upsize it.

Did you upgrade the service? A 25 kw load is a significant load that the POCO I'm sure wants to know about. Perhaps your inspector can answer your questions since he's the one sending in cut-in cards. That's probably what I would do is call the local EI.

BBQ · 09-14-2011, 05:27 PM

My guess is, when it fails or when it cannot supply the voltage that is required by the local rules.

BBQ · 09-14-2011, 05:29 PM

One other thing, before you get the power company involved you might want to look at their terms of service and find out if they require being notified before a 25 KW load was added.

BBQ · 09-14-2011, 05:30 PM

Quote:

Originally Posted by Magnettica

A 25 kw load is a significant load that the POCO I'm sure wants to know about.

Yeah, that dawned on me as well, that is 104 amps at 240 volts.

Cletis · 09-14-2011, 05:35 PM

Yeah. It's all legit. Did a 150-200 amp upgrade with added circuits and a load calc (RCO). It passed and that is when the POCO tech came out and looked at service. I've notice around here they tend not to do things until they blow up or get enough complaints. I know it technically needs to be upsized I"m sure of,but, if they do that's another story.

randas · 09-14-2011, 05:59 PM

I just did my first tankless.. 80A at 240. Walked down the street and there are 6 houses on a 15kva...

meadow · 09-14-2011, 06:44 PM

If the houses are all Electric in the area I see that transformer failing very prematurely. Hopefully its fused right and wont go out with a bang

.

If diming is a problem the house should have its own 25-50kva unit. File a complaint with poco.

Magnettica · 09-14-2011, 07:01 PM

Quote:

Originally Posted by BBQ

Yeah, that dawned on me as well, that is 104 amps at 240 volts.

This is an issue going forward all over the country. From what I understand is that if an upgrade past 200 amps is in order then the POCO needs to know about the added load. That's a PSEG requirement. I'd imagine that other poco's have similar rules and regulations.