I have a 3 phase 30 amp disconnect switch that was sent out to a job, it is being used as
A disconnecting means for a fujitsu mini split air conditioning system which is a 1 phase 208 volt system. In the disconnect there is a # 10 jumper between the load side of B phase to the line side of A Phase. Can anybody tell me why the jumper is there?

Thanks

Maybe to power a control circuit with a smaller fuse? Who know?

Either way it is hack work.

Maybe but why wouldn't they just jumper on the line side?

Like I said, maybe they wanted the whole thing protected by the two single phase fuses and needed a smaller fuse for the control circuit.

Yea,
I see what you are saying, will check submittals tomorrow.
Thanks for the insight,

Is this an un-fused disconnect? Are you sure it's a factory jumper? Was the disconnect supplied by the OEM, or did it come from the supply house?

Sounds to me like someone wanted a convenience receptacle that was not switched by the disconnect, but didn't want to run a separate 15 amp line. (I've seen HVAC guys do stuff like this)

Whatever the reason, it is a code violation.

Whatever the reason, it is a code violation.
How's that?

Hack work? Yes.
Violation? ?

How's that?

Hack work? Yes.
Violation? ?


There's a couple. If the jumper were installed to attempt compliance with 210.63 (Convenience receptacle powered from line side of line side of HVAC disconnect) it was probably a 15 or 20 amp receptacle. If the branch circuit was rated over 20 amps, this would be a violation of 210.21.

Jumpering a switch is a violation of 404.15(B):

Where in the off, position, a switching device marked OFF position shall completely disconnect all ungrounded conductors to the load it controls.

Even if its not an NEC code violation, you can bet it will be a life safety code violation.

Hack work... I agree!