On Mon, 16 Dec 2013 13:15:05 -0500, Nate Nagel
wrote:

On 12/16/2013 11:44 AM, Mis-application of listed appliances ---
inadequate branch circuit protection. wrote:
replying to bud-- , Mis-application of listed appliances --- inadequate
branch circuit protection. wrote:
null wrote:

(B-1 is protection of the cord of a listed device) Also B-3
(protection of listed extension cords). 15A receptacles are allowed on
20A circuits. You are saying that the listing requirements of devices
and extension cords with a 15A plug do not allow them on 20A circuits?
I see no reason to believe that is true (and it would be absurd).
Perhaps a cite? Try 110.2 (approved). "Listed" apparatus is normally
"approved" and 110.3-A (examination) would not normally be done. But
110.3-B (used in accordance with listing) is applicable. Fires are
likely from not using according to the instructions.


Let's say your listed device utilizes a power cord with a NEMA 5-15 plug,
and your branch circuit protection is rated at 20 amperes.

1) the listed device is rated for use from not more than a 15 ampere
circuit breaker (look at the ratings on extension cords). 2) the power
cord is essentially a resistor wired in series with an
appliance (light, microwave, refrigerator, etc.)
3) I square * R = the "real" power of this resistive component of the
"listed" device.
4) a 20 ampere circuit breaker will allow approximately 78% more real
power in that power cord than what it was evaluated as for it's
"Listing". 5) 78% more "real" power can easily burn up an extension cord.

Now try to tell the Fire Marshall it's OK to interface "Listed" appliances
that utilize NEMA 5-15 plugs and cord sets with branch circuit protection
of 20-amperes. I've tried ... and I'm convinced all of the rework &
repair due to the hurricane damage in New Orleans is deficient ... and
that they still have latent shock and fire hazards due to their arrogance
and ignorance. We will always have fires at X-mas due to "overloading" as
long as they ignore the requirements. No one is held accountable.


Your argument is somewhat valid, but you're not going to get anywhere
with it as the NEC specifically allows the use of NEMA 5-15 or
combination 5-15/5-20 receptacles on a 20A branch circuit.

This is the ONLY instance that I'm aware that a receptacle is allowed
which accepts a plug/cord cap of a lower nominal amperage than the
circuit breaker, however.

Note that the NEMA 5-15 receptacle *is* rated for 20A. The plug that
fits into it is only rated for 15A, though. As has been point out
here many times, the outlet can have two 10A appliances plugged in.