My home panel has a main breaker 200 amp, but it is 4 breakers (4 x 200 amp)with at tie bar....shouldn't it just be a 2 pole?

What you have is very likely a GE panel.

The breakers are actually four single pole 100 amp breakers rigged with an internal common trip mechanism and set up in such a way that two 100s are paralleled on each phase giving a total ampacity of 200 amps per phase.

I have this very panel in my own house.

[This message has been edited by iwire (edited 04-10-2006).]

Yes they are GE.

Why does GE do this versus using 2 of 200 amp breakers?

I can only imagine it is cheaper.

The first manufacture I remember doing this was ITE (Siemens). GE and Square D (Homeline) must have liked the idea since they started doing the same thing.

curt

Seimens used to do it also. Circa 1990.

If you look at max sum of breaker stab, it may be below 200A. Many of the stab ons are rated at 145-165 max sum of each stab, due to either the reduced contact area of that type of breaker, or the way the buss-work is cut and bent, might reduce cross-section.

GE has a really small contact area on stab breakers.
Murray/Siemens have reduced cross-section.
Older CH, and SqD QO just dont have either to make higher amperage CBs work out without burning the busswork.
Newer CH have bigger greased pads for contact on the stab in CBs in the 50 to 200 range.

Our PM just found out the hard way about this very issue, trying to get a 320/400 MM w/ 200A and another 200 out of the 200 distribution portion of a 20/40 in the same panel. (165A Max sum per stab)

FYI If you need CBs for feeders in the 100 -200 range you may be better off with bolt on's.

Some tears back, an engineer explained to me that the 4-section GE main breaker is comprised of two currect-sensing sections (like a 2-pole, 200a breaker) and two parallel contact-only sections (sort of like fully-rated auxillary contacts) for lower overall contact resistance.

Larry I bet he was guessing.