250A 24VDC Power Distribution Panel and SCCR

[mspuddy@electro-matic.com]

We are a UL508A Panel shop and have been asked to build a 24VDC 250A power distribution panel. My question, is would I be able to apply UL508A sticker on this (assuming all components meet spec), and if so, do I need to show an SCCR on the label for a DC panel ? If so is it the same as what the values are for AC ? Simple floor standing enclosure with a 250A main and 30A branch breakers.

 

[Jraef]

We are a UL508A Panel shop and have been asked to build a 24VDC 250A power distribution panel. My question, is would I be able to apply UL508A sticker on this (assuming all components meet spec), and if so, do I need to show an SCCR on the label for a DC panel ? If so is it the same as what the values are for AC ? Simple floor standing enclosure with a 250A main and 30A branch breakers.

SCCR would only apply to the incoming AC supply components. UL would apply to everything in the box. Have you found a 24VDC power supply that is UL listed? UL has several separate listing specs for power supplies, and as of 2016 for UL 508A panels, you can only use two of them. Your power supply must have a UL 61010-2-20 listing to be able to utilize it at its full capacity. If it has a UL 60950-1 listing, you must de-rate it by 50% to use it in a UL 508A panel, so that means buying and supplying a 500A unit.

 

[mspuddy@electro-matic.com]

Power Supply

Power Supply

SCCR would only apply to the incoming AC supply components. UL would apply to everything in the box. Have you found a 24VDC power supply that is UL listed? UL has several separate listing specs for power supplies, and as of 2016 for UL 508A panels, you can only use two of them. Your power supply must have a UL 61010-2-20 listing to be able to utilize it at its full capacity. If it has a UL 60950-1 listing, you must de-rate it by 50% to use it in a UL 508A panel, so that means buying and supplying a 500A unit.

We are not providing the power supply, this is just a Power Distribution Panel.

 

[mspuddy@electro-matic.com]

SCCR in a DC Power Distribution Panel

SCCR in a DC Power Distribution Panel

My UL rep is stating I need to mark this with a SCCR, even though it is all DC. States "this is a lot of power". But SCCR ratings and charts are all based on AC voltages......confused

 

[paulengr]

SCCR is the short circuit current that your panel can withstand not as a power source. So if I have a DC power supply with a shirt circuit output of 5,000 ADC will your panel fly apart from the magnetic force? As an end user I need to know that and current limit if needed. This is a consequence of building industrial control panels to the UL 508/508A standard. If you don’t like this pick another UL equipment category. You mentioned it’s a distribution panel. Why not rate it as one?


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