paralleling a 2 pole breaker

Status
Not open for further replies.
jim dungar said:
I said "open at the same time". It is very hard to have both contacts perfectly matched, as soon as one starts to draw an arc (which creates resistance) the current will begin to rise in the other contact; so by the time the circuit is broken, one contact may be doing most of the work. I am not saying this the reason against paralleled OCPD's, only that it may be part of a reason.
Click to expand...

Ok I do understand your point now. Thanks
 
It the world of data centres, it is not unusual to have paralleled breakers at the most critical point of the system and then each is rated for the full expected load. That most critical breaker is the output of the UPS, just before it meets with the manual bypass feed. Breakers fail, and a failed breaker is big downtime.

If there is an overload the UPS will eventually shut down. If there is a bolted fault then both breakers will open.
 
dbuckley said:
It the world of data centres, it is not unusual to have paralleled breakers at the most critical point of the system and then each is rated for the full expected load.
Click to expand...

I have no doubt, but those installations are not under the NEC.
 
Twoskinsoneman said:
I did say a two pole breaker. Meaning two poles mechanically tied together.

Who decides that the NEC applies to them? We as a company choose to impliment the standards of the NEC just like any state etc...

I we choose to impliment the NEC why wouldn't Article 240 apply to the breakers we use?
Click to expand...
if it's a 2 pole breaker then how will you get it to be operating at 120 volts?
 
Twoskinsoneman said:
:grin: Anyone else like to tell me I don't fall under the NEC or shall we "call it a day"!?
Click to expand...

Well, if you choose to comply with the NEC, it itself says that you don't have to meet its requirements ... so not complying is complying<g>

BUT, I think all understand now that you wish to follow or exceed standards that would apply to your equipment if it were installed elsewhere where the NEC requirements did apply.

Depending on the breaker characteristics, even with the handles tied together, one tripping for whatever reason MIGHT not open the other. The argument that power could remain when a visual apparent trip only cleared one parallel path seems valid, and IF SO, very unsafe.
 
I have seen panel manufactures do this, I can't remember the brand, I think it was Crouse Hinds or something like that, which used parallel 100's to make a 200 amp main, Of course this was a manufacture who custom made the breaker with a common handle tie and probable common internal trip to open and close the contacts nearly simultaniously. So as a manufacture, you could do it, but the liability lawyers would probally recommend against doing it.
 
Also this looks to be a motorhome control panel, as I don't think boats have jacks. (I know it says shore power, but that term is also used in the RV industry.)
 
I was going to mention the panels that hillbilly mentions above. Essentially they use a _4 pole_ 100A breaker, but connect pairs of poles in parallel to 'make' a 200A 2 pole breaker.

Field installing breakers in this fashion would violate the NEC, however as a factory assembly approved by UL or some other testing lab, this is kosher.

Far from 'the NEC doesn't apply, have fun and call it a day', if the NEC doesn't apply, then this probably means that some other standard applies. I bet that you could parallel breakers in exactly the fashion that you describe, but only if you jump though lots of hoops with UL; far simpler to use a single breaker of the appropriate amp rating.

-Jon
 
hillbilly1 said:
I have seen panel manufactures do this, I can't remember the brand, I think it was Crouse Hinds or something like that, which used parallel 100's to make a 200 amp main,
Click to expand...
winnie said:
I was going to mention the panels that hillbilly mentions above. Essentially they use a _4 pole_ 100A breaker, but connect pairs of poles in parallel to 'make' a 200A 2 pole breaker.
Click to expand...
It was explained to my by an engineer that the two inner bodies contain the 200a trip mechanisms, and the two outer bodies only contain contacts. This reduces the voltage drop across each phase's paired contacts.
 
LarryFine said:
It was explained to my by an engineer that the two inner bodies contain the 200a trip mechanisms, and the two outer bodies only contain contacts. This reduces the voltage drop across each phase's paired contacts.
Click to expand...

IMO he is mistaken, I am willing to bet there are two 100 amp trips in parallel.
 
steelersman said:
if it's a 2 pole breaker then how will you get it to be operating at 120 volts?
Click to expand...

You have to read more closely before asking questions, this two pole breaker is not going in a typical panel. :smile:
 
iwire said:
You have to read more closely before asking questions, this two pole breaker is not going in a typical panel. :smile:
Click to expand...
I did. I guess my feeble mind can't grasp these things as well as yours can. You are definitely far superior to me. I aspire to be just like you one day. :)
 
GeorgeB said:
Well, if you choose to comply with the NEC, it itself says that you don't have to meet its requirements ... so not complying is complying<g>

BUT, I think all understand now that you wish to follow or exceed standards that would apply to your equipment if it were installed elsewhere where the NEC requirements did apply.

Depending on the breaker characteristics, even with the handles tied together, one tripping for whatever reason MIGHT not open the other. The argument that power could remain when a visual apparent trip only cleared one parallel path seems valid, and IF SO, very unsafe.
Click to expand...

I don't use handle ties myself. I can't think of a situation where a 2pole breaker wouldn't be the better choice. Also I am pretty sure that a breaker with a handle tied to another is NOT likely to open the breaker it is tied to when tripped.... I haven't researched that myself but I was one of the 80-90% of people at the last Mike Holt conference I went to that raised their hand when Mike asked if we thought it WOULD. Being embarassed about raising my hand incorrectly kinda locked it into memory.
 
LarryFine said:
Got a spare 4-section breaker and a drill?
Click to expand...

Well sort of but it is powering half my home. :D

Larry let logic be your guide.

So what the engineer is saying to you is that even though they used already in stock and manufactured 100 amp frame size cases that they went and custom designed a 200 amp trip unit that they somehow shrunk to fit in a 100 amp container.

It makes no sense and I doubt it could be done at a reasonable price.
 
steelersman said:
I did. I guess my feeble mind can't grasp these things as well as yours can. You are definitely far superior to me. I aspire to be just like you one day. :)
Click to expand...

Here's a question I can not answer, maybe you can help me out.

Why is it that about half of your posts are rudely critical of other members (Some recent examples "You have no clue" "How did you get past the third grade") and you see no problem with that, but when I disagree with a post of yours without making it personal you cry like a baby?

It's a puzzler.:confused:
 
steelersman said:
wouldn't that be wiring it in series not parallel?
Click to expand...
steelersman said:
if it's a 2 pole breaker then how will you get it to be operating at 120 volts?
Click to expand...
Take a look at my post #11. The second paragraph was my guess as to how this thing would be wired. The OP agreed with that guess.
 
Status
Not open for further replies.
Top