Need suggestion for 125A bolt on circuit breaker

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Nefarious Mind

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Hello and thanks for reading,

We have a Siemens 800A panel:
Cat. No. S5C75LM800ATS
S.O. 79-59460-A00
Type S3S5

We are utilizing BL type bolt on circuit breakers and the largest we can find is a 100A breaker. Unfortunately we need a 125A breaker. Is anyone here familiar enough with this panel that could make a suggestion for a 125A breaker that would be suitable for use?
 
You will not be able install a 125 amp breaker in that panel unless it has a position for a 200 amp frame size breaker.


If you have no choice but to get a 125 amp feeder from this panel you may need to purchase a new interior or do a feeder tap of the 800 amp feeder.
 
petersonra said:
it seems odd to me that an 800A panel would not have a space for a 200A frame CB.

is that common?
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I agree with you, seems odd. Perhaps it is a feed through panel?

The OPs panel may have empty spaces for 200 amp frame size but they would not be called type BL.



My experience with panels that use BL type breakers is that the limit is 100 amp frame size for BL. For larger breakers you would have to order the panel board with some spaces for the BLs and then a totally different bus configuration to fit a 200 amp breaker.


Here is a good example, you can see it has a sideways main at the top, spaces for BLs below that and a spot to install one 200 amp frame size breaker at the bottom.

tk0231%252520%25289%2529__51289.1409750991.1280.1280.jpg
 
Change to a I-Line panel.

Somewhat being funny yet at same time somewhat dead serious.

Sounds like the BL line only allows for 100 amp maximum and you need to go with some different product line if you want a 125 amp breaker, or as mentioned - tap the feeder.
 
I am not familiar with that series - more familiar with the p series. Is it old? Check with a siemens guy and probably you can get a different mounting kit for a different frame breaker. Iirc Siemens calls it a strap kit. For example, I had a siemens p4 1000 amp that had a mixture of bl and qj breakers in it - it's all just in the strap kit that adapts from the large bussbars.
 
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I think we might be over-thinking the situation. To clarify I've added an image of the panel. The BL breakers are in the middle. The one in question is the one labeled cooling tower. We are currently using a 100A breaker. We are replacing an old electric motor and pump with a newer larger one. Pushing our calculated load to 113A. Our wires are of sufficient size, but the breaker is now too small. I haven't seen any BL rated at 125A so I am open to suggestions. I imagine it will end up being a Frame/Molded case breaker, but could use some help in picking the right one.
 
Nefarious Mind said:
View attachment 16252

I think we might be over-thinking the situation. To clarify I've added an image of the panel. The BL breakers are in the middle. The one in question is the one labeled cooling tower. We are currently using a 100A breaker. We are replacing an old electric motor and pump with a newer larger one. Pushing our calculated load to 113A. Our wires are of sufficient size, but the breaker is now too small. I haven't seen any BL rated at 125A so I am open to suggestions. I imagine it will end up being a Frame/Molded case breaker, but could use some help in picking the right one.
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Sure that isn't a switchboard instead of a panelboard?

It likely has a common bus, then sub assemblies that plug onto that bus to adapt to different breaker types, The BL is likely only availiable up to 100 amps and you would need a different sub assembly to connect something over 100 amps to - if there is any space left that will accept such assembly.
 
Nefarious Mind said:
I think we might be over-thinking the situation.
Click to expand...

No it is pretty much as I thought.

You cannot put a 125 amp breaker in those middle positions. Those are BL positions and as far as I know there are no 125 amp BL breakers.

You might be able to add a 'finger kit' for another pair of 200 amp frame size breakers below the bottom four breakers but I would not count on it.
 
kwired said:
you would need a different sub assembly to connect something over 100 amps to - if there is any space left that will accept such assembly.
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I agree, that is the question for sure.

Looking at it more closely the panelboard looks top fed so as long as the neutral assembly (if it has one) was not placed dead center at the bottom it looks like there is space for anther pair of 200s once you buy the bus bar fingers and new trim pieces.
 
I would also be likely to try a 100 amp breaker first. If this is supplying a motor and especially if it is/was across the line started, There would have to be a pretty significant increase in motor size before you would overload the 100 amp, holding during the starting surge may be a different issue, but if new one is on a VFD or soft start - it may never be a problem at all, even if increased in capacity a little, like from a 50 to 60 HP or something like that.
 
Is space to mount additional breakers available behind the blank spaces at the bottom of the panel? E2/E4 and QJ2 breakers are available in 125A, and the mounting hardware to mount either frame size is listed in the Siemens catalog. The mounting kit will have provisions to mount 2- E frame or 2-QJ2 breakers.
 
Trust me I've considered running on the 100A considering that some of my measured values add up to 93A (new motor included, but measured on a separate circuit). The FLA adds up to 113A.

Do circuit breakers typically open exactly at their rated value or is more of a nominal number like most electrical values?

My place of work is not shy of fudging things to "get it to work," but I am afraid of sag on the motor as it heats up. As it gets warmer it starts to pull more amps bringing us closer to that 100A threshold. We can't have the circuit breaker constantly "popping" open considering its running our cooling system on our dynamometers.

Let me know what you guys think.
 
Not sure where you got those numbers, but that's a P4 panelboard.

BLs, and all of the series that fit on those bus supports, stop at 100A.

You will need an add-on kit for another series of breaker. Here are all of the ones that will fit, they are all 125A frame breakers.
ED2, ED4, HED4, ED6, NGB, HGB, LGB, NEB, HEB
In addition you could use 225AF breakers like the Q2 series, because they go down to 125A, but you are buying a larger frame breaker so it may be more expensive.

The difference will be based on your voltage and interrupt capacity and whether or not you need internal accessories. Most likely though, it will come down to what's available at your friendly neighborhood Siemens distributor. You not only need the breaker itself, but you need a "kit" of the bus connection parts and a new cover plate.
 
Nefarious Mind said:
Hello and thanks for reading,

We have a Siemens 800A panel:
Cat. No. S5C75LM800ATS
S.O. 79-59460-A00
Type S3S5

We are utilizing BL type bolt on circuit breakers and the largest we can find is a 100A breaker. Unfortunately we need a 125A breaker. Is anyone here familiar enough with this panel that could make a suggestion for a 125A breaker that would be suitable for use?
Click to expand...

I have had a similar problem. Needed to go from 100 amp to 150 amp. The only solution was to change the piece that held the breaker and change the breaker across from the new breaker(the fingers in the kit were the same as existing fingers for the BL breakers). The whole change cost just over $4,000.00 dollars in materials.
 
Mgraw said:
I have had a similar problem. Needed to go from 100 amp to 150 amp. The only solution was to change the piece that held the breaker and change the breaker across from the new breaker(the fingers in the kit were the same as existing fingers for the BL breakers). The whole change cost just over $4,000.00 dollars in materials.
Click to expand...

Yeah, pretty much plan on obscene prices for panelboard parts and single breakers. My siemens guy and I were playing around with some breaker prices with panelboard vs stand alone. Some examples:

3 pole 200 amp breaker, (FXD63B200), $371.00 when you buy it in the panel versus $1760.21 afterwards.
3 pole 400 amp breaker (JXD63B400) $826.40 in the panel versus $2909.45 afterwards.

Hey, good rule of thumb: 4 times the cost, both copper wire over aluminum, and larger frame breakers bought after the fact :)


Of course you can get larger frame breakers for around the "with panelboard price" on line/ebay, but for panelboard parts, you are kinda stuck.

A few years ago I had to get a strap kit to put a few more BL breakers in a P4. I dug around in my email for the price, but couldnt find it. Maybe somewhere around $400 (would mount 2 - 3 poles) is the best I can remember.
 
electrofelon said:
Yeah, pretty much plan on obscene prices for panelboard parts and single breakers. My siemens guy and I were playing around with some breaker prices with panelboard vs stand alone. Some examples:

3 pole 200 amp breaker, (FXD63B200), $371.00 when you buy it in the panel versus $1760.21 afterwards.
3 pole 400 amp breaker (JXD63B400) $826.40 in the panel versus $2909.45 afterwards.

Hey, good rule of thumb: 4 times the cost, both copper wire over aluminum, and larger frame breakers bought after the fact :)


Of course you can get larger frame breakers for around the "with panelboard price" on line/ebay, but for panelboard parts, you are kinda stuck.

A few years ago I had to get a strap kit to put a few more BL breakers in a P4. I dug around in my email for the price, but couldnt find it. Maybe somewhere around $400 (would mount 2 - 3 poles) is the best I can remember.
Click to expand...
That is one reason why I Line is better. Not that buying just one breaker is necessarily cheap, but no need for adapter parts. Then if you have a 30 year old I line you want to add a breaker or two you just buy a small main lug panel and the breakers you need and even a couple spares, for less then just one of them would have cost you, and the breakers will fit the 30 year old panel with no adapters necessary.
 
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