Terminal Markings - Labels vs Manual?

[Norbert77]

I have some single-phase 24VDC power supplies in an industrial control cabinet with a 208VAC wye supply.

The power supplies are rated for universal input, from 100 to 240VAC or something like that. The manufacturer stated over the phone and in an email that they can be connected in this case to either 120V (L-N) or 208V (L-L). One of the manuals specifically calls out 208VAC as a supply voltage option. I want to connect them L-L for current draw reasons.

The issue I'm having is that because the supply terminals are marked L and N on the device itself, the reviewer for this design is insisting that they must be connected L-N, despite what the manufacturer says.

Is there anything in the NEC, NFPA 79, or UL 508A that covers something like this?

 

[SceneryDriver]

I have some single-phase 24VDC power supplies in an industrial control cabinet with a 208VAC wye supply.

The power supplies are rated for universal input, from 100 to 240VAC or something like that. The manufacturer stated over the phone and in an email that they can be connected in this case to either 120V (L-N) or 208V (L-L). One of the manuals specifically calls out 208VAC as a supply voltage option. I want to connect them L-L for current draw reasons.

The issue I'm having is that because the supply terminals are marked L and N on the device itself, the reviewer for this design is insisting that they must be connected L-N, despite what the manufacturer says.

Is there anything in the NEC, NFPA 79, or UL 508A that covers something like this?

Switchmode power supplies couldn't care less if they're connected L-L or L-N, as long as their max voltage isn't exceeded. To whit: many switchmode supplies carry, in addition to their acceptable AC input voltage range rating, a DC input voltage range rating as well. Ask your reviewer how he would deal with that.

If the product literature lists 208V as an acceptable supply voltage, than it's acceptable, per manufacturer's literature. Your reviewer must have too much time in his day to worry about things like that.

Alternatively, select a different power supply to satisfy him; I'd be reluctant to do that though. Sounds like the reviewer needs a bit of education. For what it's worth, I build UL508A panels, and I've never been questioned by my inspector for doing exactly what you describe.


SceneryDriver

 

[petersonra]

Some power supplies have terminals labeled with numbers like 1 2 3 4 5.

 

[LarryFine]

Ask the manufacturer for revised labels marked L1 and L2.

 

[Jraef]

In countries outside of North America, 230V is actually L to N...

There is no code stating what terminals should be marked as, other than the terms "Line" and "Load" on things that have both. Your reviewer is a paper pusher with no knowledge of what they are looking at. I would ignore it, or put some wire labels over the terminals saying L1 and L2.