A long long time ago I was told that wafer breakers don't perform well in comparison to full sized breakers. I can't recall just what was said, but I keep thinking my JW was trying to tell me that, perhaps, a certain brand of wafer breakers weren't thermal magnetic, but just magnetic. I've never run into any wafer breaker that wasn't thermal magnetic, so I keep trying to figure out what that JW was trying to teach me. Anyone have a clue about some controversy about using wafer sized breakers instead of full sized ones...other than the issue of cramming too many of them in a panel?
Elzapper:
Are you refering to the GE brand "thin" breakers??
We/I had a problem with them many years back.
Noticed that the ones we had troubles with were made "off shore" and the problem free ones were domestic. Complained to supplier, returned the CB's for domestic ones.
BTW, we/I have not used/installed these breakers in a long, long time. We stay with full size CB's, and try to stay with SqD QO's for 120 volt applications.
If you're talking about another type/brand, let us know please.
John
I thought it had something to do with the ability to dissapate heat. Because the other breaker mechanism was so physically close it could not radiate the heat as well.
Hotline1, I "think" I'm referring to the typical 2 for 1 arrangement, like Cutler Hammer's (takeover of Bryant?)BD1515, or Seimen's QO1515, etc. I'm not sure what breaker type my ole JW was referring to because by the time I had a chance to think about it enough to realize that what he said just didn't add up, the guy was transferred to another job! For all I know he might have been referring to Zinsco breakers. I doubt that he was referring to the normally thin GE breakers. Anyway, it stuck in my memory enough to nag me whenever I come across these twin breaker types, so I'm just trying to settle my nagging doubts. Its a bum deal when an apprentice gets misinformation...which is what I expect has happened in this case for me.
Jim M, what you said certainly is appropriate, and I suppose that is why the provisions for twinning breakers are located down in the bottom of the panels.
Small aside: For NEC applications, magnetic-trip-only circuit breakers are limited to use in combination motor starters only in conjunction with motor thermal-overload protection in a listed combination.
This effectively disqualifies their use for plain-vanilla branch-circuit application. An example of intended use are Cutler-Hammer HMCP or GE TEC motor-circuit protectors.” {Can’t locate the applicable Article 240 or 430 section.}
hotline i do agree with you about those compact breakers like ge breakers which it do bring me back some memories about it. it gave me a sour taste with it especally try to get use the duplex verson to run 220 or 208 volts on 2 pole set up some case it ran only 110 volts . and what more i try to check the panel board what is the limit of number of breaker it can take.
btw yeah ch breaker do make duplex single pole breakers and sq d also BUT sd d have 2 versions so watch out due the stab cam below the breaker
merci marc
Elzapper:
OK, I now know what you mean. (we call them piggy backs, tandems, twins)
To the best of my knowledge, they are all thermal magnetic.
I believe taht "heat build-up" is a major problem with these units, and there use should be severly limited.
I had an instance recently with a 42 circuit panel, that had 20+ "twins" jammed in.
I also have seen "combo" twins...2-2 pole within the space of two normal cb's. factory handle ties on the two center, and the two outer handles; cute..ha??
John
John,
I am used to the ones your taking about but check out the 1/2 space SP 30 on this link,
I guess this is so you can make any combo you want SP 30 and SP 15 in one space.
Bob
http://store5.yimg.com/I/breakerbroker_1728_1317133
Many of the main breakers supplied on the output of portable generators are of the "dual-magnetic" design. These magnetic only breakers are not the same as the "instantaneous trip" magnetic only breakers used for motor circuit protection.
Many electricans have developed myths to prevent the use of twin/wafer/tandem breakers.
The truth is, there is nothing wrong with using these breakers as long as they are only installed in panel spaces designed to handle them. I have never seen a tandem breaker with a time-current curve substantially different than a full size one.
There is nothing wrong as, long as 2002 NEC 408.15 is not violated
No more then 42 overcurrent devices in a panelboard (other then the main)