Electrical Engineering

Author

208 to 240

solaron@att.net

2007-01-25, 5:25 pm

Anyone ever swapped a 208 main for a 240 going to a residence. There
is a manhole cover one house down with both mains running alongside.
It's doable, but was wondering about cost, (especially from the utility
for switching), general experience, etc.
Thanks

phil-news-nospam@ipal.net

2007-01-26, 1:25 pm

On 25 Jan 2007 12:21:26 -0800 solaron@att.net wrote:

| Anyone ever swapped a 208 main for a 240 going to a residence. There
| is a manhole cover one house down with both mains running alongside.
| It's doable, but was wondering about cost, (especially from the utility
| for switching), general experience, etc.

Let's see if I understand correctly. 208Y/120 goes by the house. The
utility would get you 2-legged 208/120, but that means your 240 volt
stuff is underpowered. You want to know what is involved in turning
that into genuine 240 volts?

I'd say you are better off just taking the 208 as is. Let that run all
the 120 volt loads as is. Then take off a 2-pole circuit and feed that
through a 208-to-240 single phase dry transformer. From there, it goes
to a smaller subpanel just for the loads that need genuine 240 volts.
This keeps the transformer smaller.

Loads that do NOT use a neutral could be boosted to 240 volts with an
even smaller buck boost transformer. The line-to-ground voltages will
be higher than 120 volts, but not by a great deal. But loads that DO
need a neutral need a full isolation transformer to get them right, or
would have to be doubling a single 120 volt phase to 240.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-01-26-1257@ipal.net |
|------------------------------------/-------------------------------------|

Beachcomber

2007-01-27, 3:25 am

On 26 Jan 2007 19:04:26 GMT, phil-news-nospam@ipal.net wrote:

>On 25 Jan 2007 12:21:26 -0800 solaron@att.net wrote:
>
>| Anyone ever swapped a 208 main for a 240 going to a residence. There
>| is a manhole cover one house down with both mains running alongside.
>| It's doable, but was wondering about cost, (especially from the utility
>| for switching), general experience, etc.
>

You need to know why you got stuck with 120/208 in the first place.

Was it easier for the utility to tap off an existing transformer
serving some nearby business, apartment or condo? Do you have your
own (exclusive) distribution transformer?

You didn't say where you lived, but in the USA, the standard service
for single, stand alone residential dwellings is 120/240V. There must
be some pecular reason why you got stuck with 208V.

In general, if it involves the utility swapping or installing a new
transformer, they probably won't do it, unless you pay.

Beachcomber

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