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.

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