Variable-Speed Controls and Explosion-Proof Fans

Using a variable-speed controller likely voids the explosion-proof rating on a fan. August 14, 2007

I recently purchased a 20 inch Jenny variable speed explosion-proof fan. I have done some electrical myself, and was wondering if anyone out there has hooked up their own variable speed model and could offer some assistance.

Forum Responses
(Finishing Forum)
From contributor L:
Usually an explosion-proof fan cannot be variable. When the fans are operated slower than spec speed, the temperature rises above the tolerance that keeps them within the explosion-proof rating.

From contributor D:
I mean this in the nicest way. When it comes to electrical work, if you have to ask, you should probably not be doing it. We all have our limits of expertise. The difference could be as simple as a call to an electrician or a call to the coroner. Your money or your life?

From the original questioner:
Thanks for your concern, but I think it's more dangerous not to ask. I called Jenny and got tech support, black (hot) to yellow line wire from motor neutral (white in line with variable speed switch), ground (green to earth ground). I already tested, works great. Also, why would they sell a variable speed version if it were not intended to function that way?

From contributor L:
You can put a VS unit on the explosion proof fan and it will function properly. It will no longer be classified as an explosion proof fan because the case can rise above the threshold temperature.