UL Class 2 Circuits

[theColonel26]

Ok am finding UL 508a section 44 rather vague....

Does the Power supply that supplies a Class 2 Circuit have to be Listed for UL Class 2?

If No

Does the Power Supply have to be limited to 100W output?

Or

If I use fast blow fuses to limit circuits to less than 100W. Are those circuits Class 2 then?

[ndzied1]

If the panel will be inspected for listing make your life simple. Use a class 2 power supply.

There are several available.

The class 2 rated power supplies have circuits that guarantee power limiting above what regular power supplies have.

[theColonel26]

Well I would need a like 3 separate Class 2 power supplies instead of 1 240W power supply.....
Do most people just use more than one power supply if then need more than 100W?


That also takes up a lot of room

[padees]

I've been using Class 2 Electronic Circuit Breakers for a number of years now. RTFM...

[theColonel26]

So it seems no one actually knows the answer to my questions.... As no one has directly answered them.

[rupej]

My recollection from talking to our UL inspector was that fusing down to <100W was sufficient.

[theColonel26]

Originally Posted by rupej

My recollection from talking to our UL inspector was that fusing down to <100W was sufficient.

thank you

[atc222]

Originally Posted by theColonel26

thank you

And the above is wrong. Class 2 is limited to 100 ma. Either a class 2 power supply, or class 2 converter. Something like a 1692 ELP.

Fusing doesn’t cut it per UL.

And yes, I often have a class 2 power supply in addition to say a 240W power supply.

Cheers!

[theColonel26]

Originally Posted by atc222

And the above is wrong. Class 2 is limited to 100 ma. Either a class 2 power supply, or class 2 converter. Something like a 1692 ELP.

Fusing doesn’t cut it per UL.

And yes, I often have a class 2 power supply in addition to say a 240W power supply.

Cheers!

100 milli Amps... ?

[atc222]

Sorry, 100VA (aka watts.) 3.8A, 24Vdc is typical.

Apologies for not answering your initial question. Yes, it needs to be listed as a UL class 2 power supply.

Remind me not to post after drinking….

[theColonel26]

Originally Posted by atc222

Sorry, 100VA (aka watts.) 3.8A, 24Vdc is typical.

Apologies for not answering your initial question. Yes, it needs to be listed as a UL class 2 power supply.

Remind me not to post after drinking….

ok that is what I figured you meant just wanted to check



Where is the fun in that?

[atc222]

Lol! Cheers!

[Rson]

Originally Posted by theColonel26

Well I would need a like 3 separate Class 2 power supplies instead of 1 240W power supply.....
Do most people just use more than one power supply if then need more than 100W?
That also takes up a lot of room

Use a 240W power supply. Then use a class 2 electronic circuit breaker such as the Allen Bradley 1692 series or Siemens Selectivity modules. Depending on the module, you can usually get 4 class 2 circuits from one.

There are other companies that make them as well - and I believe Automation Direct may have a new electronic circuit breaker - not sure what it is though.

[titanspark76]

I also would just use the 240watt power supply along with a Class 2 distributor. I linked a few different ones I've used. Maybe you'll get lucky and one of them will actually be in stock somewhere

Puls
https://products.pulspower.com/us/pisa11-class2.html

Murr
https://shop.murrelektronik.com/en/E...rPage=10&pos=1

Omron
https://www.ia.omron.com/products/fa...ification.html

[atc222]

Now that I'm back in the office.

Puls CD5.241-L1. Is what we typically use DC/DC Converter 3.8A Class 2.