On 5/14/2013 6:38 PM, bud-- wrote:
On 5/14/2013 6:41 AM, Robert wrote:
When my house was being built, I asked that the
electic hot water heater be put on a plug so that
I could easily unplug it and plug in my welder,
which is only used once in a while.

I was told that this was not allowed and the
electric water heater was hard wired to the
feed.

I'm Ok with that, obviously, but I wonder the
reason that the code wouldn't allow the hot
water heater on a plug disconnect, like the
electric clothes dryer.

Does anyone here have a suggestion as to
what the problem would be that the code
has to mandate a hardwired connection ?

The NEC covers allowed cord connections in 400.7.
Permitted uses that are relevant a
6. Connection of utilization equipment to facilitate frequent
interchange.
8. Appliances where the fastening means and mechanical connections are
specifically designed to permit ready removal for maintenance and
repair, and the appliance is intended or identified for flexible cord
connection.

Number 8 applies to electric stoves and clothes dryers.

Neither apply to water heaters (or furnaces).

Uses not permitted are in 400.8
1. As a substitute for fixed wiring of a structure.

Can you cord an plug connect an outside air conditioning
compressor/condenser?

Someone looked up requirements in UL standards for cords and romex. A
lot of the tests for cords were for flexibility, much different from
romex.

A possible 'compromise' might be a disconnect at the water heater with
a receptacle wired before the disconnect.

------------------------------
Regarding a similar recent thread, on furnaces if I remember right,
the NEC explicitly allows garbage disposers to be cord and plug
connected.

I use an electric water heater that is cord and plug connected. The
manufacturer didn't intend it to require periodic disconnection and
removal, but my particular installation required it. I only use it for
summer hot water. I kill my boiler and indirect domestic hot water tank,
and connect the electric with stainless steel flex hoses, flip a couple
of valves and plug it in. Clearly, the manufacturer didn't intend it to
be connected in this fashion, but it works for me. Some times you just
gotta cheat.