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Bud--

wrote:
On Thu, 29 Oct 2009 10:50:29 -0600, bud--
wrote:

I have never seen an installation with a delta breaker. Catalog pictures
what I remember is a delta breaker has 2 bus stabs and a wire. The wire
goes to the neutral bar?
Is this the only way delta breakers are used?

"Delta" breakers are really only telling you they have higher line to
ground ratings. The normal breaker you see in 120/240 is really only
rated 120v nominal to ground. In a delta you always have at least one
leg above 200v to ground. In corner delta you have 2 at 240v above
ground. The place you are likely to see corner delta is in a sewer
lift station where the only load is the pump and a control panel that
runs l/l at 240v. That will usually be open delta too.
The panel will look like a single pole (2 hots and a grounded leg)
unit but the tip off is 240v to ground and 3 p loads. That is really
the one you have to look for "delta" breakers in. All 3p breakers I
have ever seen are rated that way.
Although a corner delta panel looks exactly like a 120/240 panel, it
still needs to be listed for delta (higher voltage). I suspect it may
only be the label ;-)

An example would be to compare a QO230H "delta" breaker $200
with a QO230 120/240 breaker (the one on your water heater) $67

That is list price, you will beat that by up to 60% on the regular
breaker but you might not on the delta breaker.

Interesting.

A few posts back I mentioned a "delta breaker" then you mentioned "delta
rated breakers". My last post confused the distinction. I looked in the
SquareD catalog and your delta ratings are easy to find. They are
supposed to have a catalog for corner grounded delta but I haven't
searched for it yet. Should reinforce the info you provided above.

I looked in an my old electrician's handbook and it shows a "delta
breaker" as a 3-phase breaker except it only has 2 bus connections. The
third connection comes out to an additional lug. In use, you have high
leg delta service entrance wires but a single phase panel. The delta
breaker plugs into the panel and picks up the 120V legs. The service
high leg connects directly to the additional lug on the breaker. The
only 3-phase available is on the load side of the delta breaker - to
equipment or a subpanel. Everything else in the service panel is single
phase. I suspect they were used to add some 3-phase load to a single
phase panel - you just add 3-phase service wires and meter to the
existing single phase panel. To be safe you also add a 3-phase common
trip circuit breaker as a separate service disconnect. They could also
be used as one of the service disconnects in a split bus panel.

I looked on google (Holt) and delta breakers have not been allowed in
panelboards since 1978 (408.36). I sure have never seen one. But I
remembered seeing them in the NEC which is why I was interested.

--
bud--