[Boatfan63]

I have two attic gable exhaust fans, each with a thermostatic control box. One at each end of the attic. When I looked inside the control box of the one at the far end of the attic (power off at breaker) I saw something I had not seen before. Here is the background, and the question.

There is a wall switch at the entry end of the attic which controls both attic gable fans.

Two romex cables (each with black, white, and ground wire) entering the thermostat control box from below on the fan at the far end of the attic. An armored cable exits the thermostat box and connects to fan motor.

All grounds were connected together.

One of the black wires was connected to the black wire supplying the fan motor (across the thermostat connection).

One of the black wires was capped with a wire nut.

All three white nuetral wires (the two entering the box, and the white wire from the thermostat controller) were connected together with a wire nut.

Any thoughts on why it might have been done that way, and whether I should be concerned. The setup appears to have been operating normally for years.


Thanks

 

[surferdude2]

It may have been rendered an unneeded feed when it was decided to allow one fan's thermostat to control both fans (which would be desirable). If that's the case, then the spare black will be a home run that should be marked as "attic spare" or whatever.

That type of setup would require the secondary fan's thermostat to be set so it would always be on damand and waiting for the power to come from the main fan via that second cable.

 

[Boatfan63]

Thanks for your feedback surferdude2. Actually each fan is controlled by its own thermostat. The thing that seemed odd to me was that all three nuetral wires were capped together (both romex and white neutral from fan controller), but only one of the black romex leads entering the box was capped to the fan thermostat (leaving one black romex capped by itself). My concern was that by having an used black romex wire capped, and it mating white neutral attached to the other nuetrals, I might have a situation that is undesirable. It's not easy to see where the exiting romex (with the capped black wire, and nuetral white joined to others) goes after it leaves the box. If it was intended to power something else ( a switch or outlet downstream), clearly without the black lead connected that should not happen.

Anyway, I do appreciate the feedback, and was hopeful that an unused capped black 14/2 romex lead, with it white neutral connected to other neutrals in the box, and with all grounds connected was not a hazard.

Cheers