On 2/3/2012 6:30 PM, mike wrote:
On 2/3/2012 1:34 PM, Horace Greeley wrote:
On 2/3/2012 7:22 AM, RBM wrote:
On 2/2/2012 11:05 PM, wrote:

I've seen furnaces connected with a twist-lock plug - it meets the
requirement for a disconnect within reach of the furnace.(takes the
place of a switch) and is also a foolproof way of connecting to a
genset.

That maybe true in Canada, but it doesn't meet 422.16 of the Nec, in the
U.S., at least not for your garden variety central heating system.


Check with your local electrical inspector.

If done properly, ours said it was legal and safe to do the plug and
cord setup.

His only recommendation was to use a 12 gauge appliance cord set, proper
strain relief (not romex clamp) and a high-quality 20 amp receptacle.

I went thru the same process.
Prevailing opinion is that devices permanently attached to the structure
must be permanently wired. Heating system seems to be permanently attached.
Reading the NEC, it appears that's what it says.

The Nec requires that it be designed to be unattached , and removed for
servicing, for a cord and plug to be used. Not too many central heating
systems that meet that criteria.

So, I went down to the permit office and talked with the inspector.
He said, "no problem; putting a socket in the box and plug on the wire
will pass my inspection".