300v fuses

[Capital]

I pulled a fuse disconnect 3ph, 200amp, 480v and found a A3T200 protecting each leg. Looking at the fuses it says they are rated with 300v. That cant be right, can it? Is it protecting only the 277 to ground.

 

[infinity]

Usually they're 300VDC and/or 600 VAC.

 

[jim dungar]

It is not uncommon to find 300V Class T fuses.

 

[infinity]

It is not uncommon to find 300V Class T fuses.

Will they fit in a 600 volt disconnect?

 

[Capital]

Then I can replace the bad fuse?
They do fit.

 

[Capital]

1200 amp service with (8) meters, the individual 200 amp fuses pull out all at once in a harness

 

[jim dungar]

Will they fit in a 600 volt disconnect?

They only fit into disconnects specifically designed for them.

 

[Capital]

See attached

 

[Capital]

Yes they fit

 

[infinity]

See attached

I don't see an attachment. Do you have some photo's?

 

[Capital]

 

[infinity]

Are you saying that those fuses were in a 200 amp, 600 volt disconnect switch?

 

[Jraef]

View attachment 2565355

Nope. That fuse is only rated for 300VAC max, if you have 480V you need the A6T for 600VAC max. Doesn’t matter that the L-N is 277V, it’s based on the line volts.

The A6T is 1/2” longer, so either you have a 300V rated disconnect being used on 480V, or someone deliberately moved the lower fuse block. Either way it’s because someone didn’t know what they were doing. You cannot replicate their error and continue doing it wrong. You will be the last person to touch it so you now own the error if you fail to rectify it.

 

[Capital]

In touch with the fuse Rep. now.
Thank you

 

[Capital]

Are you saying that those fuses were in a 200 amp, 600 volt disconnect switch?

That’s what my problem is.

 

[infinity]

That’s what my problem is

Do have some photos?