750VA (.75KVA) CPT in NEMA 1 enclosure

[mshields]

I'm specifying a single phase 750VA CPT type transformer (with integral fusing), to power some 120V lights off a 277V circuit.

I've got the catalog number on the CPT and I've specified it in a NEMA 1 enclosure.

Is a NEMA 1 enclosure, ventilated by definition. Or should I specifiy a ventilated NEMA 1 enclosure to account for heat?

And on what basis should I size the enclosure.

Mike

 

[George Stolz]

I subscribed to this thread hoping to see some replies, and didn't see any when I returned.

I have a couple questions, in addition to the one Mike asked: does this have to be treated as an SDS? Why or why not?

 

[jim dungar]

I'm specifying a single phase 750VA CPT type transformer (with integral fusing), to power some 120V lights off a 277V circuit.

I've got the catalog number on the CPT and I've specified it in a NEMA 1 enclosure.

Is a NEMA 1 enclosure, ventilated by definition. Or should I specifiy a ventilated NEMA 1 enclosure to account for heat?

And on what basis should I size the enclosure.

Mike

Check with the manufacturer for the size of the "optional" enclosures they offer, these are usually the smallest volume possible. And no, enclosures are usually not considered ventilated by default.


George,

If this is an isolation transformer why wouldn't it be treated as an SDS, size does not matter.

 

[cadpoint]

And what what kind of enviroment is this going into.
Match the existing construction.

My second thought as far enclosure is, is this going to be on 24/7 or just 8 hours or less ?

2047.2 (included 1.25% rule) BTU/hour can't any NEMA 1 enclosure handle that ?

Say the object is 32 Sq in. isn't a factor or muptiler or 5 safe in Engineering?

For those at home playing along this is 2047.2 equals to or approx of 6.5, 3 lamp-2 X 4's (VA not BTU's)

 

[Jraef]

I would also reconsider the idea of using a CPT for that purpose. CPTs are better than "regular" transformers when powering inductive loads with high inrush currents such as starter coils etc., but that capability (and its ensuing cost) is wasted on lighting. Just get a Plane-Jane old distribution transformer; it will come in its own NEMA 1 enclosure ready to go.

 

[petersonra]

I'm specifying a single phase 750VA CPT type transformer (with integral fusing), to power some 120V lights off a 277V circuit.

I've got the catalog number on the CPT and I've specified it in a NEMA 1 enclosure.

Is a NEMA 1 enclosure, ventilated by definition. Or should I specifiy a ventilated NEMA 1 enclosure to account for heat?

And on what basis should I size the enclosure.

Mike

Unless you install the thing in an area with an elevated temperature to begin with, I would not be worrying all that much.