10k branch breakers in a 22k panelboard

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sdbob

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I have a client that owns many buildings, two of which I visited yesterday to take a look at existing panels for jobs there. Both jobs have 600-amp, 3-phase, 208y/120 panelboards in them, series rated at 22k, being fed by mains rated 65k. I found 10k branch breakers in both panels, and advised them to change all breakers to 22k breakers. This client got a second opinion from another electrician who told them "it doesn't matter". What advise would you give my client?
 

jim dungar

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Hard to tell with knowing specifics.

It is completely possible that a 65kAIC main breaker has a 22kAIC series-combination rating with 10kAIC branch breakers.
 

iceworm

Curmudgeon still using printed IEEE Color Books
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EE (Field - as little design as possible)
I have a client that owns many buildings, two of which I visited yesterday to take a look at existing panels for jobs there. Both jobs have 600-amp, 3-phase, 208y/120 panelboards in them, series rated at 22k, being fed by mains rated 65k. I found 10k branch breakers in both panels, and advised them to change all breakers to 22k breakers. This client got a second opinion from another electrician who told them "it doesn't matter". What advise would you give my client?
I'm guessing you don't know the available SSC at the panel. If you don't know - I can't think of any advise you could give the owner on this subject.

ice
 

sdbob

Senior Member
I'll get the ssc, and post a pic of the nameplate when I get back to the office. They're series rated to 22k, and the nameplate says to install only 22k breakers.
 

augie47

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Tennessee
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State Electrical Inspector (Retired)
In my experience, it's a hard sell to a person not versed in the electrical field. Your client can't see, smell of see fault current and all his lights are on. Push the issue too much and that other electrician will be doing all the work.
My suggestion is to permit the next job you do, discuss the situation with the inspector and let him carry the ball. We are used to being "the bad guys".
 

Strathead

Senior Member
I'll get the ssc, and post a pic of the nameplate when I get back to the office. They're series rated to 22k, and the nameplate says to install only 22k breakers.

With this additional information, it is clear what is required. Any work that you do in the panel needs 22KAIC breakers or a professional available fault current calculation needs to be done to change the panel AIC rating.

The rest is a little unclear. I would give the customer a written clearly worded statement that explains the requirement and a polite statement that you can not do any work that violates the NEC and an exclusion for any problems involving the incorrect breakers. If I was feeling vindictive, or didn't like the other Contractor, and I believed the customer, I might report them to the State Board. Probably not though, we aren't our Brother's Keeper.
 

sdbob

Senior Member
nameplate # 1, (one panel is series rated, the other is not)
 

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jim dungar

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If these two panels are electrically near each other, they most likely require the same ratings. It looks like the first panel came from the factory and the second panel was a 'field' addition. Series-combination labels must be field installed, if the panel did not come 'pre-labeled'.
 

sdbob

Senior Member
I don't have enough info for the fault current calculation, and frankly have never done one. The series rated board is fed with a 65k 600 amp breaker from a 3000 amp service, parallel 350s about 90' long. The other panel is 600a, parallel 350s about 30' long, fed from a 600 amp main (probably CL fuses, I'm not sure) in a 2000 amp main service.

The building with the 3000 amp gear is fed with a transformer that is not shared, but I'm not sure of the size. I'd guess 750kva. The building that's fed with the 2000 amp service likely shares a transformer with other buildings on the property so I have no clue what size it would be.

My job in both buildings is minor and requires the addition of several circuits. Given the nameplate data it's clear the panels require 22k breakers.

The seimans BL (10k) and the BLH (22k) look identical except for the label. The BLH breakers used to be grey I believe, but they're not anymore. And the BL-H breakers are twice the price.
 

sdbob

Senior Member
If these two panels are electrically near each other, they most likely require the same ratings. It looks like the first panel came from the factory and the second panel was a 'field' addition. Series-combination labels must be field installed, if the panel did not come 'pre-labeled'.

The buildings are on two different properties.
 

sdbob

Senior Member
There's no question that the panels require 22k breakers, and the breakers I install will be 22k. The problem is they both contain many 10k branch breakers that I advised should be swapped out to 22k breakers. My client got a 2nd opinion that advised them it wasn't necessary.

It's such a technical issue, and hard to describe to the client with out using hyperbole like "your breakers might explode before they trip".
 

jim dungar

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Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
Siemens does have series-combination ratings for BLH with 600A fuses. The panel should have a field installed label, indicating that series rating are being used, if they are.

BL breakers are limited to 10kA when protected by fuses.
 

bob

Senior Member
Location
Alabama
sdbobe
Can you verify the 750 kva and while you are at it, get the %Z. Maybe we can make a SWAG at it.
I would make a WAG but the SWAG is more accurate.
 

sdbob

Senior Member
sdbob
Can you verify the 750 kva and while you are at it, get the %Z. Maybe we can make a SWAG at it.
I would make a WAG but the SWAG is more accurate.

Thanks Bob... there's no need to go through the trouble. Clearly the panels require 22K breakers. My point for the thread was to show my client several other informed opinions on the importance of installing the correct breakers for her panel. The thread kind of went sideways, lol.

As it stands I'll just leave the existing 10k breakers in there, install new 22k breakers for my work, and note such on the invoice.
 
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