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#126510 - 03/24/06 09:51 AM Furnace Sure Suppressor
wendel Offline

Registered: 08/07/04
Posts: 57
I want to use a generic computer surge surppressor for my furnace due to all the ICs now on the control circuitry. I will get one that can handle the wattage of the furnace.

Can I have a switched receptacle at the furnace into which I plug the surge suppressor and then plug the furnace line into the surge suppressor? I can't think of any code violations but then I'm only a homeowner. Thanks.

#126511 - 03/24/06 10:42 AM Re: Furnace Sure Suppressor
ghost307 Offline

Registered: 05/09/05
Posts: 883
Loc: Chicago Illinois USA
Hi, Wendel...
One of the first questions that I ask myself about any type of installation is "has anybody else done it like this"? If the answer is NO, I usually assume that there's some reason why it isn't done.
Other than the obvious reasons for not powering your furnace the way that you describe (it gets unplugged, more stuff gets plugged in, you're running 15 Amps through a teeny little wire), there is a Code item that says that you can't do it.

422.16 Flexible Cords.
(A) General. Flexible cord shall be permitted (1) for the connection of appliances to facilitate their frequent interchange or to prevent the transmission of noise or vibration or (2) to facilitate the removal or disconnection of appliances that are fastened in place, where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance or repair and the appliance is intended or identified for flexible cord connection.

This would apply to a window air conditioner, washing machine, or other item that would need to be disconnected for frequent services or changeout.
Since the furnace that gets built into the house if usually the same one that's there for 20 years, you'll need to hard-wire this one. Even if you try to say that the flexible cord should be there for vibration, you'd need to hard-wire that cord into the circuit.

If you're really concerned about surges, there are several manufacturers of surge protectors that can be wired directly into the wiring. Ask at the local DIY store and tell them that you don't want one that's a plugstrip...they should be able to accomodate you.
If not, I'm sure that one of us here on the forum could give you a steer to a suitable product.

Remember to read the instructions, work safe, and turn off the power when working.

#126512 - 03/24/06 01:18 PM Re: Furnace Sure Suppressor
wendel Offline

Registered: 08/07/04
Posts: 57
Thank you, ghost, for your thoughtful reply. Now for a follow-up. Is Romex considered 'flexible cord'? It would be easy enough to reconnect a short piece of Romex to the surge suppressor (removing the flexible cord) and then connect that piece of Romex directly into the furnace power switch box. The furnace would have a Romex piece with the male plug for the surge suppressor.

I have seen the surge suppressors that one can wire into a circuit at the main breaker box. However the closer the suppressor is to the equipment, the better its effectiveness will be.

#126513 - 03/24/06 03:57 PM Re: Furnace Sure Suppressor
hbiss Offline

Registered: 12/16/03
Posts: 893
Loc: Hawthorne, NY USA
Wendel, I'm going to chime in here and tell you that we are not permitted to give advice to people who are not in the trade.

The reason should be plain to you, there is no code compliant or safe way to do what you want with a power strip. None, nada, zilch. So forget it. Only a homeowner or DIY's would think up such a thing.

The question is even whether your furnace controls need to be surge protected anyway. I suspect that since it is permanently installed there is some kind of protection already designed in. If you want to be on the safe side there is hard-wired surge protection that can be installed at the furnace.

I would suggest that you contact an electrical contractor who will do this for you rather than risking the safety of yourself and your family.


#126514 - 03/24/06 07:22 PM Re: Furnace Sure Suppressor
gfretwell Offline

Registered: 07/20/04
Posts: 9026
Loc: Estero,Fl,usa
The right way to do this is to install (or more correctly, have installed by an electrician) a panel mounted surge suppressor. That will not only protect your furnace, it will also protect your other stuff. Have your electrician verify that the telco and cable company is connected to your electrical service ground electrode.
Greg Fretwell

#126515 - 03/25/06 08:14 AM Re: Furnace Sure Suppressor
Tiger Offline

Registered: 05/04/05
Posts: 714
Loc: Crystal Lake, IL USA
You didn't give us any information to go on in your profile, but I think "Young & Foolish" probably covers it. If you have a wife & children, do them the simple courtesy of increasing your life insurance before thinking up any more cool electrical projects. You might consider a safer hobby...

and we aren't here to help you kill yourself.


#126516 - 03/25/06 08:50 AM Re: Furnace Sure Suppressor
Roger Offline

Registered: 05/18/02
Posts: 1779
Loc: N.C.
Wendel, as far as a "plug in" type of surge suppresor and you plugging it in per your first post, this would be fine, but your second question is going into wiring methods and altering equipment, so I must close this thread.

NM can not be used the way you are proposing to use it.

You should consult a local electrician.



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