3 phase service

One consideration that is not electrically oriented is if there is a house fire and there is no meter for the firefighters to pull for their safety, they will just stand by and watch the house burn.

Paul

Open Delta. Only two transformers, and ONLY two high voltage lines to feed the TWO transformers. Pretty common all over.

Three phase can be had off of two hi voltage primary wires. It is just that you have no choice but to go open delta on the lv.

John

Yuck. You're right. But you do have to have a neutral referenced to the hv wires.

What an ugly kludge. I'm surprised anyone would use such a thing.

Slab type transformers aren't particularly difficult to locate outdoors or indoors.

An armor channel covers the HV side conductors downward along the side of the utility pole, as underground service is typical with pad xfmrs.

Various sizes of outdoor-duty types can be seen around commercial sites, and also mobile home parks and campgrounds.

In a wire mill environment where I worked years ago, the KV lines were run underground into the facility, and the switchgear, xfmrs and various cabinets were mounted on a reinforced overhead slab standing on beams. The 3-phase 460VAC circuits were branched out with buss systems.

Yes, but typically the utility will only provide a pad mount if the user is not close enough for secondary service from a pole or existing pad mount.

All the plants that I do maintenance in are old.... transformers all sit behind a chain link fence.

Now that I think about it most residential developments around here are fed underground with a nice neat little pad and transformer a couple of feet high and about 4 foot square. A commercial installation would be just a little bit bigger.

I'm surprised that the electric co. doesn't supply you the transformer for free if you use a minimum amount of power.

John

Personal would be on the ground seems to me.

Small company ? - larger one ?

Building contractors put them in neighborhoods - have overages ? Cosmetic ?

Mart>

Ugly ? - add another transformer and you have true 100% power 3 phase.

With two - and that two gave you three phase and split 220 as well.

So it used the center tap on the right side If split 22O came from the house on the underground - and the three phase from the pad transformer, then only three secondary wires are used.

The Military and police/fire all use Three Phase. Delta-Delta.

The idea - overrate the transformer by at least 1/3 but normally 1/2. Then if or when worse comes to worse, and an input leg is lost, or a winding is lost (bullet...) the secondary can continue at ~66% e.g.

100% of wanted (due to overrate.) They could take a hit on the primary and secondary and still stay alive.

Mart> john wrote:

Meter on the pole or in the pad transformer - normally on the end and the sides hinge open. Nothing is hardwired by professionals.

Our big pad units had meters on then.

Mart> >> "The Kid" is putting in underground wiring to his outbuildings. For