Nameplate ratings vs building supply in Canada

[wizardcoremonk]

Hey all, I'm a new member and this is my first post. I know this site is primarily for questions related to US installations and the NEC, but I was hoping I could appeal to some members that may have some insight into requirements in Canada. Even some rationale from the NEC may be helpful. So here's what I got.

I work for an OEM that makes power supplies. We recently shipped a system that utilizes a transformer with a 480 Delta primary. It's not a UL listed piece of equipment, so we enlisted a field evaluation service that approves equipment for general safety to SPE-1000 (a CSA safety code). He required us to change the nameplate input voltage from 480 to 480/277. My thought is that the nameplate should reflect the rating of the equipment, and the equipment requires 3 hots and a ground. His reasoning is that the equipment is approved for a Wye 4 wire system, but that doesn't mean a neutral is required to be run to the equipment. I can't wrap my head around his reasoning. To me it seems it may cause some confusion for an installer who may look at that nameplate and run a neutral when one isn't required.

So my question is, does his reasoning make sense to anyone here? Could you explain it to me?

Hopefully I've been clear enough, just let me know if I need to provide any more info.

 

[GoldDigger]

Hey all, I'm a new member and this is my first post. I know this site is primarily for questions related to US installations and the NEC, but I was hoping I could appeal to some members that may have some insight into requirements in Canada. Even some rationale from the NEC may be helpful. So here's what I got.

I work for an OEM that makes power supplies. We recently shipped a system that utilizes a transformer with a 480 Delta primary. It's not a UL listed piece of equipment, so we enlisted a field evaluation service that approves equipment for general safety to SPE-1000 (a CSA safety code). He required us to change the nameplate input voltage from 480 to 480/277. My thought is that the nameplate should reflect the rating of the equipment, and the equipment requires 3 hots and a ground. His reasoning is that the equipment is approved for a Wye 4 wire system, but that doesn't mean a neutral is required to be run to the equipment. I can't wrap my head around his reasoning. To me it seems it may cause some confusion for an installer who may look at that nameplate and run a neutral when one isn't required.

So my question is, does his reasoning make sense to anyone here? Could you explain it to me?

Hopefully I've been clear enough, just let me know if I need to provide any more info.

He is correct in that without making any change to the transformer, that part of your equipment will work with either a 480 delta supply or a 277wye supply. That gives the customer the option to connect either 3 or 4 wires depending on what they are supplying to it. If they supply it from a 277wye, they still do not have to wire a ground to it. (Somewhat mind boggling to me at first too, but I can sort of see his point.)
If the input was 480 delta only, then you would be forced to assume that the supply was either corner grounded or ungrounded or neutral of 240/480 high leg grounded. Can your equipment tolerate any of those combinations?

A good installer will look at an input specification of 480Y/277 and realize that he can supply it either way.
However, he does need to know that your transformer actually has a delta primary so that he knows NOT to connect the neutral to anything at your equipment if supplying it from a wye.