See anything wrong with this?

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iwire

Moderator
Staff member
Location
Massachusetts
As to using cord, what if a box was installed inline with the branch circuit, and the branch circuit supplies a mounted receptacle, while the load side is connected to a cord which plugs into the receptacle during normal power usage, or plugged into generator (or extension cord therefrom) for standby power?

Kind of like what was suggested in post 3?:eek:hmy:

Which brings us right back to the issue of cord and plug connecting a furnace which IMO is not allowed in 400.7 unless we want to lie and say it was to reduce noise and vibration.
 

iwire

Moderator
Staff member
Location
Massachusetts
Just exactly what is proper transfer equipment for an individual load of 2200W or less?

It might have to be a 30 amp double pole safety switch, I really do not know.

What I do know is run of the mill devices are listed for single circuit use only.
 

renosteinke

Senior Member
Location
NE Arkansas
As with dishwashers, water heaters, circulating pumps, and several other household 'appliances,' we're getting into 'design.'

Some folks want to get all persnickity and say "but the code says ..." and split / parse / dissect every word as though it were handed down from Heaven and infallible. What seems to be ignored is the idea that, just maybe, the code, or this anal application of it, is plain wrong. I doubt language is capable of ever being 'precise' enough.

Please don't bring up the idea of 'precedent.' You might as well argue that all ships are required to hit icebergs, because we 'let' the Titanic do it onece.

Another comparison: speed limits. Is doing 50 in a 30mph zone a violation? What if you're doing 31? How about 30.00001mph? Does it really matter that you can't read the spedometer that fine? I don't see where the law required you to even have a speedometer. The law only requires you to obey the limit; how you comply is your problem.

That, my friends, is called the 'reduction to the absurd' argument. Carry anything to its' logical extreme and it's absurd.

So, as for all this worry about putting cords & plugs on equipment ... I'm not going to lose any sleep. Proper strain relief, proper size wire, proper plug ... I don't have a problem. I sure prefer it to a whip of Romex poking through a jagged hole in the wall, then entering unprotected and unsecured into a KO. I prefer finding a plug to finding an open junction box with wires dangling everywhere.

Having received a 9-hour power outage as a Christmas present this season, I am rather partial to the idea of mounting a second receptacle in the furnace cabinet, and having this receptacle ultimately connect to a small portable generator. Kind of makes the transfer both simple and goof-proof. I am partial to having heat on 25-degree winter days.

Flexible cords not approved for this use? Well, I'm not sure Romex is approved ffor the use either. I'm not comfortable with Romex sailing through the air for any distance - be to feed the furnace or the garbage disposal. For that matter, slipping a sleeve of flex over the Romex accomplishes .... what, exactly?

I'm not comfortable with forcing the serviceman to take apart wires to disconnect things. Why have him work "hot" when we can have him plug things in?
 

peter d

Senior Member
Location
New England
Flexible cords not approved for this use? Well, I'm not sure Romex is approved ffor the use either. I'm not comfortable with Romex sailing through the air for any distance - be to feed the furnace or the garbage disposal. For that matter, slipping a sleeve of flex over the Romex accomplishes .... what, exactly?

Yeah, that romex might suddenly burst into flames because it's sailing through the air. :roll:
 

rcwilson

Senior Member
Location
Redmond, WA
A possible issue with a DPDT switch is the voltage and interrupting rating of the contacts. Imagine that the generator is running the furnace and the power comes back on. Your wife runs downstairs and flips the switch back to utility while the furnace blower motors are going full blast. The generator is definitely not in synch with the utility so the 120V switch can easily have 240V or more across the contacts. The arcing from interrupting the motor currents could jump the gap or weld the contacts putting the generator in parallel with the utility. Best case, you burn off some contact life. Worst case, you get to buy a new generator.

The receptacle sounds better. Maybe put a sign on it to turn off the furnace before unplugging. Code compliant? -??? Practical? Yes.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
A possible issue with a DPDT switch is the voltage and interrupting rating of the contacts. Imagine that the generator is running the furnace and the power comes back on. Your wife runs downstairs and flips the switch back to utility while the furnace blower motors are going full blast. The generator is definitely not in synch with the utility so the 120V switch can easily have 240V or more across the contacts.
277V switches are common and pretty cheap. I have not seen a two pole, double throw, 30A, 277v (and maybe throw in "center off") But I haven't looked for one either.

ice
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
277V switches are common and pretty cheap. I have not seen a two pole, double throw, 30A, 277v (and maybe throw in "center off") But I haven't looked for one either.

ice
They make toggle switches with that kind of rating and in some cases with a mechanical interlock that requires you to stop in the center off position and release the handle before you can throw to the other side, but these would have to be mounted in an interface box rather than being a device-box-compatible snap switch..
 

templdl

Senior Member
Location
Wisconsin
His concern is having to open the enclosure to operate the disconnecting means.

It appears as though there are concerns about being exposed to live parts then. Any of the transfer switchses tat I'm aware of were able to be operated with being exposed to life parts. They were available with NEMA 1 and NEMA 3R enclosures.
 

Smart $

Esteemed Member
Location
Ohio
It appears as though there are concerns about being exposed to live parts then. Any of the transfer switchses tat I'm aware of were able to be operated with being exposed to life parts. They were available with NEMA 1 and NEMA 3R enclosures.
Well there are always concerns about being exposed to live parts... but that's not the issue he is objecting to. It's simply a matter of the operating handle(s) not being readily accessible per Code.
 
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