Single phase transformer for network cabinet

[RNLENI]

Customer use to provide 120V AC single phase for my network cabinet in the past. But now they are planning to provide only 3 ph 480 VAC.
So I am planning to install a 480 Vac to 120vac single phase encapsulated transformer (two phases of the 480 supply at the primary). NEMA 3R is the cheapest transformer.
Also I would need an upstream protection for the transformer. So I am going to use a fused disconnect upstream, NEMA 4.

My load (network cabinet )already has a breaker already .

1) So , Do I need to have a separate downstream protection (fuse/breaker) of the transformer ? may be for protecting the conductor from transformer downstream to the network cabinet ? If so is it mandatory? Code says about sizing upstream and downstream protection . But in my case I am using fused disconnect upstream of the transformer and my load cabinet already has a breaker in it.

So do I need to have another breaker /fuse just downstream of the transformer?

Also does this NEMA 3R transformer good for industry/ warehouse environment ? its rated for indoor and outdoor. But I usually use enclosures that are NEMA 4 or NEMA 12 , IP 56,66 etc.

 

[DrSparks]

Customer use to provide 120V AC single phase for my network cabinet in the past. But now they are planning to provide only 3 ph 480 VAC.
So I am planning to install a 480 Vac to 120vac single phase encapsulated transformer (two phases of the 480 supply at the primary). NEMA 3R is the cheapest transformer.
Also I would need an upstream protection for the transformer. So I am going to use a fused disconnect upstream, NEMA 4.

My load (network cabinet )already has a breaker already .

1) So , Do I need to have a separate downstream protection (fuse/breaker) of the transformer ? may be for protecting the conductor from transformer downstream to the network cabinet ? If so is it mandatory? Code says about sizing upstream and downstream protection . But in my case I am using fused disconnect upstream of the transformer and my load cabinet already has a breaker in it.

So do I need to have another breaker /fuse just downstream of the transformer?

Also does this NEMA 3R transformer good for industry/ warehouse environment ? its rated for indoor and outdoor. But I usually use enclosures that are NEMA 4 or NEMA 12 , IP 56,66 etc.

You don't need additional OCPD if you are primary protected.

NEMA 3R is rain proofing. It really is designed to divert rainfall around the enclosure and also provide draining for any water that makes it inside. You wouldn't benefit much if you are in a corrosive or dusty environment. NEMA 4x is basically completely sealed and would offer protection for harsh environments.

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