225 KVA Isolation Transformer

Status
Not open for further replies.
P

Purr24

Member
Location
Pennsylvania
Occupation
Electrician
I am installing an Isolation Transformer Prime 480v and Sec. 480v for a CT Scan room. I have a fused disconnect on secondary side of transformer first means of disconnect are my Neutrals and Grounds bonded together at this switch
 
Purr24 said:
I am installing an Isolation Transformer Prime 480v and Sec. 480v for a CT Scan room. I have a fused disconnect on secondary side of transformer first means of disconnect are my Neutrals and Grounds bonded together at this switch
Click to expand...
If the secondary is a wye system then you would need a system bonding jumper on the secondary side. It could be at the disconnect. I think it might need to be a service rated switch.

You would also need a grounding electrode system and a grounding electrode conductor connected to this same point.

There would be no connection of the neutral between the primary and secondary side, except via the EGC.
 
#3 switched removed 175 amp breaker in A1 switch
d4559ef0e814f137961251cda0cbc128.jpg


Sent from my Pixel 2 XL using Tapatalk
 
Your print shows neutrals and grounds bonded at the transformer.

As @petersonra notes, you must have a neutral/ground bond _somewhere_, and it could be at the disconnect. But it is equally valid to have it at the transformer. There should be only _one_ neutral/ground bond.

-Jon
 
This is an isolated grounded system, and while we can debate the usefulness of such a system, the system bonding jumper needs to be at the transformer to accomplish what the engineer thinks an isolated grounding system can do.
 
I think the way to go is bond Netral and ground in A-1 Disconnect with bonding screw. Isolated ground and equipment ground all bonded together in the Transformer. So much for isolation.
 
Purr24 said:
Isolated ground and equipment ground all bonded together in the Transformer. So much for isolation.
Click to expand...
But that is how an isolated ground system should be installed. A single ground point is the intent not actual isolation, each grounding conductor/path is isolated from all other conductors/paths except at one common point.
 
Last edited:
Status
Not open for further replies.
Top