I can't locate the answer in the CODE! Help Please

[simon]

We are working in an Industrial Facility with two 4000A, 480/277V services. A branch feeds a 400A, 480/277V, QMB Load center. 5 60A buckets with 45A fuses' feed (5)five, single phase, 37.5 KVA, sola CVS x-fmrs. The x-fmrs are feeding some test equipment in their QC dept.

The x-fmr's are located inside the facility above the top of the QC room. The QMB load center is located on ground level just the otherside of a concrete block wall from the x-fmrs.

The top of the QC room is used as a storage area for alot of stuff including one large air handler. There are hand rails around it's perimiter. This area is accesible by ladder or sissor lift only (no permnant stairs or ladder).

From anywhere atop the QC room It is not possible to see the QMB load center. It is located on the other side of a concrete block wall.

My Question is this:

Don't each of these transformers require their own disconnects within sight?

I have looked under Tranfomers, Disconnecting means, Services etc... I'm not getting anywhere fast.

Thanks simon

 

[jim dungar]

Re: I can't locate the answer in the CODE! Help Please

Quick answer - NO.

In-sight-of is not a requirement for transformers (in fact a dedicated disconnect is not even required), that is why you will not find it referenced in the NEC.

 

[russ]

Re: I can't locate the answer in the CODE! Help Please

Good answer Jim.
I get the feeling that alot of people think that the insight disconnect rule is for electrical safety.
I believe it's more for mechanical safety, such as motors moving machine parts while being worked on.

Russ

 

[simon]

Re: I can't locate the answer in the CODE! Help Please

Thanks for the answer. My thought was, disconnects were for personal protection. I've done PM work on transformers as well as motors. I've been installing disconnects on xfmrs for twenty years. Not that it's a bad thing, it just isn't the minimum standard.

I guess this is another lesson learned on don't assume the person you work with no matter how good they think they are, if they start quoting the NEC look it up for yourself. "Apprenticeship 101"

 

[bennie]

Re: I can't locate the answer in the CODE! Help Please

A disconnect switch will be used for turning the transformer on and off. The switch is likely not capable of safely handling the inrush current.

Therefore, it is dangerous to have a disconnect switch on the primary of a transformer.

A disconnect switch, before a motor starter, is for isolating the starter and motor for maintenance. The switches should not be opened or closed under load, in most situations.

[ June 25, 2003, 12:53 PM: Message edited by: bennie ]