service entrance transfer switch

[dross48]

I am installing a new genset upgrade to a nursing home, the existing generator supplies only a 200 amp emergency panel, the customer wants the entire building on emergency power. The building has two 400 amp fused disconnects side by side in the electrical room being fed from power and light transformer. My question is can I install a 800 amp service entrance rated transfer switch after power and light transformer and before the two 400 amp disconnects and use the existing feeders into building? I believe this would make the transfer switch the service entrance main breaker and the 2 disconnects inside electrical room individual sub feeds.

 

[iwire]

Who owns this 'power and lighting' transformer?

Where is the existing service disconect?

Are you planing on an automatic or manual transfer switch?

What is the total calalculted load of what you want to power?

 

[dross48]

Who owns this 'power and lighting' transformer?

Where is the existing service disconect?

Are you planing on an automatic or manual transfer switch?

What is the total calalculted load of what you want to power?

Its owned by a local utility I have already coordinated it with them, the two 400 amp disconnects in electrical room are the current service disconnects, it is a automatic transfer switch. What I am planning to do is intersect the feeders going inside of building and mount the 3R service rated transfer switch at the point where we will intersect the current feeders.

 

[ceb58]

Is it truly a emergency generator falling under Article 700?

 

[augie47]

Both of the other posters are leading you to some valid questions concerning potential Code problems. I might add a question as to what is the size of the generator.

Sidestepping all their important question for a moment and looking at your questions on face value.
It would be permissible to intercept the service and install you transfer switch and re-feed the 400 amp disconnects.
If you mount the transfer switch on a structure other than the main building you could encounter a problem with (2) feeds to one building. From a Code standpoint it might be better to mount the transfer switch in/on the main building. Your conductors from your 800 amp transfer switch would need to be sized properly and meet the 240.21 tap rules and you would need to add an EGC since the 400 amp disconnect would no longer be service equipment.

 

[J.P.]

Service entrance rated transfer switch? I don't see why it wouldn't work. Add some grounds from the 400A disconnects and bond at the transfer switch.

 

[dross48]

Who owns this 'power and lighting' transformer?

Where is the existing service disconect?

Are you planing on an automatic or manual transfer switch?

What is the total calalculted load of what you want to power?

It is a 200 kw generator and a service rated automatic transfer switch and it is an emergency generator under article 700. The current situation is the utility transformer is feeding two separate fused 400 amp disconnects inside main electrical room mounted side by side, these are the service disconnects. What I am doing is mounting a 3R transfer switch just outside of building as there is no room inside existing electrical room. The existing disconnects are less than 75' from where I am going to mount switch. The way I see it is if I change the bonding and properly ground equipment this should be within code.

 

[kwired]

You say this is a nursing home. Most nursing homes don't need to meet much of art 517 requirements as far as wiring in resident rooms, but if there are special care areas - you may need to look hard at 517 part III or even other health care codes and make sure you don't need an Essential System.