Short circuit current for control panel
- Thread starter aalabrash
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ptonsparky
Tom
- Occupation
- EC - retired
I do know how much I like to see the 5kva on equipment that will be installed on projects that easily have 5 times or more available.
Especially when everything but that last piece is installed.
Especially when everything but that last piece is installed.
Thank you. My question is about SCCR calculations for control panelsI do know how much I like to see the 5kva on equipment that will be installed on projects that easily have 5 times or more available.
Especially when everything but that last piece is installed.
ptonsparky
Tom
- Occupation
- EC - retired
I know.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Yes, you can (unfortunately) apply a 5kA SCCR to a UL 508A listed panel without any effort. I call it UL’s “courtesy” SCCR listing. It’s all but useless, but technically, it’s possible.
The problem that Tom is pointing out to you is that this is a TOTAL pain in the rear for the poor electrician who is responsible for connecting it up to a system that has MORE than 5kA of available fault current. In industrial environments (and many commercial ones), that is virtually EVERY instance. There is no way for an installer to lower the available fault current without a major modification to the source of supply. So you are “kicking the can down the road” to someone with no reasonable ability to solve the problem. When that happens, they (we) curse your name, your heritage, your children or future children and the white horse you rode in on…
PLEASE do not do this. Take a few extra minutes to investigate the SIMPLE steps it might take to attain a higher SCCR for your panel. In most cases, all it takes is to look at the series listings of the power devices and MAYBE having to select brands that are coordinated with each other.
The problem that Tom is pointing out to you is that this is a TOTAL pain in the rear for the poor electrician who is responsible for connecting it up to a system that has MORE than 5kA of available fault current. In industrial environments (and many commercial ones), that is virtually EVERY instance. There is no way for an installer to lower the available fault current without a major modification to the source of supply. So you are “kicking the can down the road” to someone with no reasonable ability to solve the problem. When that happens, they (we) curse your name, your heritage, your children or future children and the white horse you rode in on…
PLEASE do not do this. Take a few extra minutes to investigate the SIMPLE steps it might take to attain a higher SCCR for your panel. In most cases, all it takes is to look at the series listings of the power devices and MAYBE having to select brands that are coordinated with each other.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
NO!
To get a legit sccr, it has to be a listed control panel. That means you have to follow all the rules in ul508a including component selection.
There are components that ul508a does not allow.
There are a few components that UL has assigned a sccr of less than 5 ka. Not many, but a few.
You have to do the calcs and pay ul (or etl) for the right to put a sticker on your panel that says it is listed.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
OK, that's a better answer than mine...
Thank you all, That's very helpful.
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