ECN Forum Forums General Topics of the Trade General Discussion Area Small Xformer

On my last service change, th PoCo hooked up yesterday, and lo and behold, put a dinky 10KVA Xformer on the pole.



The customer's original complaint was dimming lights, due mostly to the 300' long secondary, and a 60A service, circa, 1950, which I assured would be cured. (Bad mistake)

But... She plans to buy an electric on-demand water heater, which uses two 40A 240V circuits to feed heating elements.

So, I figure, if dimming lights still isn't a problem (I saw some flickering myself...) it will be...

Am I correct in asking for, say, at least a 25KVA?

The house demands out at 26KVA.



[This message has been edited by sparky66wv (edited 11-16-2002).]

sparky, in my area , when i request the power co for a larger tf, they will come out and do the math... if justified they will upgrade.

sparky66wv,

I'm assuming that you are in Allegheny Power's area.

usually when I called in for a work order number they would ask if there is any additional load.

Even if thay didn't ask and you complain they should come out and check out the situation.

Heck, when I moved into my house about 5 years ago, my lights dimmed when my NEIGHBOR'S air conditioner came on.

My house was being fed from a transformer about 300 feet away that was being shared by two other homes.

When I complained, APCo came out, installed a new transformer closer to my house and replaced the old 3 single conductor secondary feeding my house. Now I have my very own transformer.

It was a good thing for me that they changed it when they did because later that summer the old transformer feeding the other two houses burnt up in the middle of the night and had to be replaced.

Virgil,

That Custom House I designed / Installed the Electrical and Comm/Data/Security systems for back in 2000 comes to mind.

The existing SCE Xformer on the pole was 25 KVA. It feeds no less than 6 other Houses - each being at least 1500 sq. ft.

The new service is 400 amp type, and load calcs figured around 200 Amps +/-. SCE pulled two 4/0 XHHW al + one 1/0 XHHW al service feeders.

When I closed out this project (after owner's occupied), the same 25 KVA Transformer was powering everything.

Just something to ponder...

Scott s.e.t.

M'66,

Called APCo today, the lady in Fairmont made it sound promising, but I'll wait to hear from the EE. I made it sound like my fault, surprising what a little diplomacy will do!

Scott35,
Yeah, makes one wonder... Hmmmm...
I'm gonna insist on a 50KVA for my house (when I build it) and threaten lots of arc welding if I get a 10KVA!

</dreaming>

The house I live in is fed by the same 25kva transformer that feeds 11 other houses. All of them are at least 2100 square feet with electric cooktops, ovens and dryers. A few of them including my house have 5-ton central A/C units. The transformer was installed 40 years ago and still works good. One thing to keep in mind is that most utilities keep the fault current under 10,000 amps for single family dwellings. Using large transformers may cause the fault current to exceed this unless the length of the service conductors are long enough to reduce the current below the preferred 10K rating.

We wired a medical building a few years ago with a 600 amp service consisting of a 3 section switchboard. The utility installed 1-4/0 AL for each phase and 1-1/0 AL for the neutral. We had several feeders leaving the switchgear and one of them was 300 amps using 350 CU.

Curt