xfmer

[ninosparkz]

What is the requirement for mounting a panel above a xfmr?

 

[augie47]

110.26, especially 110.26(A)(3).
Unless you can mount your panel where the working space from the floor is not obstructed by the transformer it's a violation.

 

[ninosparkz]

What about the disco?

 

[raider1]

What about the disco?

What disconnect are you referring too?

Chris

 

[ninosparkz]

Eng. Calls for a disco before xfmr... can I mount it above

 

[iwire]

Eng. Calls for a disco before xfmr... can I mount it above

Not really unless you make a rack that holds the front of the disco even with the front of the transformer.

See the code sections Gus posted.

 

[charlie b]

Yes, you can mount a disconnect above a transformer. But the working clearance rules still apply. For example, if the transformer extends more than 6 inches further from the wall than the disconnect, then the transformer would be within the disconnect's required working space, and would violate 110.26. (Bob's suggested mounting arrangement would resolve this problem.)

You might suggest as a (I hate this phrase! ) "value engineering" revision, that the disconnect be eliminated from the design. The NEC does not require one.

 

[ducky10]

what if the transformer is in a diff room that either the primary or secondary panels? I have seen disc on both the prime side and the second side.

 

[charlie b]

There is no rule against having a local disconnect that serves the primary of a transformer. But there is also no rule that requires it. The NEC is a minimum standard for safety. A local disconnect may be helpful to a future maintenance person, but the NEC would not care about that.

As to the secondary of a transformer, there are limits on how far you can go, before hitting an overcurrent device that protects the secondary conductors (not the transformer secondary windings, but the wires leading away from the transformer). You can comply with those limits by installing a local secondary disconnect, but it has to be a fused disconnect. As an example from a recent project that I designed, I called for an enclosed breaker on the secondary side, and I sized it to protect both the secondary windings and the secondary conductors.

 

[infinity]

Not really unless you make a rack that holds the front of the disco even with the front of the transformer.

See the code sections Gus posted.

Here's an example of what Bob's describing: