Paralleling Breakers??

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DLCOX

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Would this be considered paralleling breakers? Where 3 - 100A single bkr was used vs a single 3 ph 225A brkr. The goal is to put a 65kW load on the UDP.
I'm not an expert but this just seems off.

Ref: 208Y/120
UDP connections.jpg vs UDP connections 1 bkr.jpg

Thoughts??

Thanks
 
In the first diagram is that just a simple drawing of 3-208 V breakers with wires rated going to the terminal block and then to an outlet? If there is the procreate wires not depicted in this diagram above if it's feeding the same piece of equipment then obviously that would not be correct.

Unless they were using it as a redundant power supply to a completely separate power strip in the rack not bonded or grounded to the rack, but with an isolated ground. Still remains the question, on the upper diagram are the wires full-size and two, not 1 wire and they appear to be going to a terminal block of some sort and then an outlet?

If what appears to be a terminal block is actually a CT of some sort for energy management that would be another question?

The bottom diagram shows a 208 V feed to one outlet and then a 120 V feet with no neutral just ground, so neither one looks like anything I've seen before and thousands of racks I've dealt with!


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DLCOX said:
Would this be considered paralleling breakers? Where 3 - 100A single bkr was used vs a single 3 ph 225A brkr. The goal is to put a 65kW load on the UDP.
I'm not an expert but this just seems off.

Ref: 208Y/120
View attachment 16630 vs View attachment 16634

Thoughts??

Thanks
Click to expand...

Welcome. 3 100A breakers isnt a parallel setup, it's 3 separate breakers. and woefully undersized for substitution of a 225A 3ph breaker.

65,000W/208/1.732 = 180A. 3 100A breakers have a total of 100A 3ph capacity, not 300A. If you used them on just one phase, that would be paralleled conductors and is an NEC violation. Cant see your 2nd pic that well but handle ties and conductor grouping would be problematic as well.
 
I see,

So really, the only way to replace a single 225A bkr with a 100A bkr is to parallel them, which obviously is an NEC violation then?

UDP connections 100 Stacked.jpg
 
What are the red and blue boxes?
If they represent a single three phase three wire (delta with no neutral) going through two connectors, it would be OK. But if they are separate loads the one with phase and ground only would be useless.
If it is a single circuit feeding a three phase load you really should have common trip across the three breakers.
And whatever the load(s) you have to have a handle tie.
As for the terminology, you do not have breakers in parallel, you have three single pole breakers for.a three phase load.

If there was a reason to have a 225A breaker, using 100A breakers as you suggest would trip on overcurrent.
A 225A three pole breaker allows 225A on each of the three poles.
To "parallel breakers" to get 225A would require three breakers per line for a total of 9, and would also be against the code unless it was a manufactured, listed, assembly for that purpose.

mobile
 
Idea was to use a breaker that could give us 65kW (80% of 81kW) load at 208V. A 225A Bkr would do the trick. The whole reason for using 100A bkrs was because of supply. There are no 225A bkrs laying around therefore would be costly to purchase them since we need enough bkrs to connect 64 Load Banks.

As far as the Load Bank connectors, they do represent a single 3 phase setup.

UDP connections 100 Stacked.jpg
 
DLCOX said:
Idea was to use a breaker that could give us 65kW (80% of 81kW) load at 208V. A 225A Bkr would do the trick. The whole reason for using 100A bkrs was because of supply. There are no 225A bkrs laying around therefore would be costly to purchase them since we need enough bkrs to connect 64 Load Banks.

As far as the Load Bank connectors, they do represent a single 3 phase setup.

View attachment 16638
Click to expand...

Your problem seems to be that you are not correctly doing the three phase power calculation. 65kW from a 208Y/120 supply requires 65,000/ (3 x 120) = 180 amps on EACH of the three phase wires. That would be a minimum of a 180A three pole breaker for non-continuous or a 225A for continuous loads (if you round down the fractional .7A)
The 225A breaker that you do not have would be just fine.
But to replace it with single pole breakers would require three 225A breakers, not 100A breakers. With at least a handle tie if not common trip.
 
If you have 3 separate 100A 3 phase breakers, and use them to supply 3 separate load banks, then you could put up to 108kW (non-continuous) of load on your supply.

If you have 3 separate 100A 3 phase breakers, and connect corresponding phases back together at a single load, then you would have placed the breakers in parallel and the installation would not be kosher under the NEC.

-Jon
 
Aside from your apparent misunderstanding of the principles of current ratings that GoldDigger keeps trying to get you to acknowledge, from a purely code standpoint you cannot use multiple single pole breakers for a multi-pole circuit, period. The code requires that with any switch or circuit breaker, all ungrounded (meaning not neutral) conductors be opened if any one of them is opened. So if you are using breakers, you CANNOT use single pole breakers in parallel. You can use FUSES that way, but you cannot use 3 separate 1 pole fused switches that way, you would use one fused multi-pole disconnect switch, even though usually only one fuse blows.

2 or 3 pole breakers have an INTERNAL connecting means so that if one pole trips, all poles open. Handle ties are not quite the same, they are for when you have multiple SEPARATE circuits that you want to operate at the same time. What I think GD was attempting to get at with the question on what those boxes represent is that this APPEARS as though you have separate loads, in which case the handle ties might be appropriate, but it's hard to tell from your depiction. But as he pointed out, if your load is 180kW, a 100A breaker is a non-starter in that aspect as well.
 
DLCOX said:
Idea was to use a breaker that could give us 65kW (80% of 81kW) load at 208V. A 225A Bkr would do the trick. The whole reason for using 100A bkrs was because of supply. There are no 225A bkrs laying around therefore would be costly to purchase them since we need enough bkrs to connect 64 Load Banks.

As far as the Load Bank connectors, they do represent a single 3 phase setup.

View attachment 16638
Click to expand...

Just curious, what are these 64 81kW loads? That's 4-5MW of power if run at once and would require ... 33,000A service on 208. :blink:

You cannot use 3 100A 3ph breakers in place of a single 225A 3ph breaker to supply a single load. Even if you could by the NEC, I find it unlikely your existing panels would have the empty space to accommodate 3x worth of breakers (using 3 100A 3ph would take 9 spaces vs 3 for the 225A) nor your service adequate to run even 5% of these load banks at once.
 
JF,

Upstream to this are 9 2MW UPSs fed from some MSBs. The room is a Data Center Vault. So eventually the entire vault would need to be tested to its max capacity. Attached is a picture of the upstream Power Distribution to give a clearer picture.

When you commission these types its generally done at 80% which is a common mark in the electrical world.

I was presented with what I showed you all and I didnt think it was the best way to go so again I enlisted you all feedback to get some thoughts on the matter.

UOP-USP-UDP.jpg
 
DLCOX said:
JF,

Upstream to this are 9 2MW UPSs fed from some MSBs. The room is a Data Center Vault. So eventually the entire vault would need to be tested to its max capacity. Attached is a picture of the upstream Power Distribution to give a clearer picture.

When you commission these types its generally done at 80% which is a common mark in the electrical world.

I was presented with what I showed you all and I didnt think it was the best way to go so again I enlisted you all feedback to get some thoughts on the matter.

View attachment 16640
Click to expand...

Thank you for the details. I stand corrected on the power and maybe panel space. istm that 64 225A 3ph breakers would be a drop in the bucket on a project as seemingly large as this one is.
 
DLCOX said:
J...
...I was presented with what I showed you all and I didnt think it was the best way to go so again I enlisted you all feedback to get some thoughts on the matter.
Click to expand...

It was a very good idea to bring your questions to us, since not only was that not the best way to go (being a code violation), but it flat out would not work because of the error in choosing the size of the single breakers.

Whoever made that initial design suggestion to you is either very careless or not competent to engineer that kind of project.

I sincerely wish you good luck with the ongoing process. It might be a good idea to bring the next suggestion back here too. :)
 
I am not seeing anything being "paralleled" though any breakers, just one image showing common trip vs one showing independent trip for three different poles. As mentioned code will likely require the common trip method for a circuit breaker, but if the protection were fuses the independent trip method is what you would ultimately have, though a common handle tie on disconnection methods is likely still required.
 
DLCOX said:
Kwired,

Let me ask this question then.

What exactly is paralleling Breakers.

DC
Click to expand...
Two line side terminals are connected to same point somewhere upstream, two load side terminals are connected to same point somewhere downstream, if subjected to ideal conditions each breaker carries half the load, such ideal conditions are difficult to achieve and is why it is not ordinarily allowed for NEC applications. If part of a listed assembly - the listing and testing of it determined it is suitable.

What you have shown is individual poles of a multi-pole supply system. You can't connect the conductors of each "pole" together or you have a short circuit. This is not paralleling, paralleling is taking same point in a current path splitting it up in multiple paths then bringing them back together again at some point, current divides across each parallel path according to impedance of each path, path of highest impedance has least current - but still has some current.

Had you brought say two 50 amp conductors to each two pole breaker as shown, then left the breaker with two 50 amp conductors and went to a common point to supply a load - and used a 50 amp two pole breaker but tried to justify that set up as a 100 amp equivalent single pole breaker, or any similar concept - that would be "paralleling breakers"
 
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