Class 2 / Class II transformer, and enclosures

[Malini6702]

Hi All,
I've been scouring NFPA 70 and read many of the posts here related to Class 2 power supplies but haven't found a relevant post. We have a Class 2/Class II power supply connected to a control board that feeds to the main control panels in a wheelchair platform lift. The power supply provides a trickle charge to four (4) manufacturer custom 12V LiFePO4 batteries, and as such is not the main power source for the machine... it's essentially like a laptop charger.
Bottom Rail (link to a photo of the bottom rail in Dropbox)
My questions:
1. the power supply connects to a control board in a rail that hides behind an accessible cover plate. For outdoor installations the lower rail allows rain to fall through and not accumulate, and the control board is coated with silicon grease. No other electronics are located in this lower rail. The manufacturer places an IP23 rating on the entire unit. Does the enclosure need to be classified as 3R?
2. the batteries are located after the power supply (obviously) and the machine is designed to operate up to 30 times in case of power failure. The components of the battery are TUV listed, but the battery is not a Class 2 listed battery; it is made only for this manufacturer. Do the batteries need to be listed as Class 2?

I would appreciate any help on this. I'm currently arguing with a young Intertek engineer, specifically because CSA B44.1/ASME A17.5-Standard for Elevator and Escalator Electrical Equipment section 1.4 states: "This Standard does not apply to devices that are rated for connection to extra-low-voltage Class 2 supply circuits as defined in the applicable electrical code." The lift meets the requirements for ASME A18.1-Safety Standard for Platform Lifts and Stairway Chairlifts.
Thank you in advance

 

[Malini6702]

What I've found in these forums so far is
"per NFPA70 article ... 725, there are no enclosure or ventilation requirements for Class 2, as long as it’s wired to line voltage inside a junction box."
this was referring to installation of dimmable LED strips.
https://forums.mikeholt.com/threads...-supply-per-nfpa-70-enclosure-needed.2552149/
Does the junction box need to be rated for 3R?

 

[petersonra]

I don't recall the code states any specific type rating has to apply to any enclosure at all.

I don't think this rail is an enclosure anyway.

 

[Malini6702]

Thanks petersonra. The rail is located between the wall and an aluminum cover plate, which sits flush with the front-facing section of the rail. Not an enclosure, but it does provide protection from unauthorized access. I'm more interested in knowing if a Class 2/Class II power supply/transformer NEEDS to have a specific UL 50E rated enclosure for outdoor use.

 

[petersonra]

Thanks petersonra. The rail is located between the wall and an aluminum cover plate, which sits flush with the front-facing section of the rail. Not an enclosure, but it does provide protection from unauthorized access. I'm more interested in knowing if a Class 2/Class II power supply/transformer NEEDS to have a specific UL 50E rated enclosure for outdoor use.

I don't think they are required to be in any special kind of enclosure. I don't recall the wording the code uses, but it does not specify a type of enclosure be used, although I think there is an informational note regarding what at least some UL types of enclosures are suitable for.

Personally I would give it some protection from the weather but it is possible the power supply already has adequate protection from the weather and does not need any additional protection. What do the instructions say?

 

[jaggedben]

In general, the NEC doesn't specify enclosure ratings, except perhaps in classified areas (article 500). It's only general requirement as far as I know is 110.3(A) which very broadly calls for equipment to be suitable for the use and implicitly refers to product listings. With the NEMA rating system, NEMA3R is generally recognized as the minimum rating necessary for an outdoor enclosure. Most AHJs would probably accept an IP rating that is substantively equivalent, although some may need education on that rating system. But the point is, *any* electrical equipment installed outdoors that requires an enclosure would generally need a minimum NEMA3R rated enclosure or equivalent. A Class 2 power supply has nothing to do with it. You can design a product that contains a Class 2 power supply inside a NEMA1 enclosure ... as long as the instructions say to only install it indoors. If you want it to be able to be installed outdoors, it would need a NEMA3R or equivalent enclosure. I would be surprised if you could get an assembly listed that didn't follow that.

 

[Malini6702]

Thanks petersonra, the power supply is IP67 rated, so that's easy.
Thanks jaggedben - I think this is the answer I've been looking for. I appreciate the detailed explanation.