L6-20P -> L6-30R

William Herrin bill at herrin.us
Wed Mar 19 01:39:46 UTC 2014


On Tue, Mar 18, 2014 at 6:54 PM, Niels Bakker <niels=nanog at bakker.net> wrote:
> * web at typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]:
>> I have had to do this at times but it is not strictly allowed by codes and
>> not at all recommended.
>
> It's an active fire hazard.  The cables aren't rated (= built) for the power
> draw.

Meh. It depends. Plug that 30 amp power strip into a 20 amp circuit.
Try to use more than 20 amps and the main breaker trips. No problem.

Plug that 20 amp power strip into a 30 amp circuit. Try to use more
than 20 amps and the strip's breaker trips. No problem.

Get a short before the strip breaker and the main breaker trips before
the wires can heat.

There just aren't a whole lot of failure modes here that result in
fire short of one or the other breaker failing. And that results in
fire regardless of the amperage mismatch.


This, by the way, is why you're allowed to plug that 22 gauge
Christmas light wire into a 15 amp receptacle even though it can't
handle 15 amps: the 3 amp fuse will blow if there's a short. Just
don't plug in anything with lower-rated wire that doesn't have its own
breaker or fuse.

Regards,
Bill Herrin




-- 
William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004



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