L6-20P -> L6-30R

Wed Mar 19 17:06:51 UTC 2014

On Wed, Mar 19, 2014 at 12:24:38PM -0400, William Herrin wrote:
> On Wed, Mar 19, 2014 at 11:22 AM, Lamar Owen <lowen at pari.edu> wrote:
> > Just replacing an L6-20P with an L6-30P on a 20A-listed PDU would be unsafe
> > and (IMO) unwise, since the breaker in the input of the PDU does not protect
> > the flexible cord's conductors from internal overcurrent faults.
> 
> Yet an 18 awg PC power cable is perfectly safe when plugged in to a
> 5-20R on a circuit with a 20 amp breaker. Get real man.

Not really, that is just a compromise in safety standards for
convenience.  It was deemed to be safe enough given the comparatively
low current 20A circuit and the open-to-air power cord.  For higher
current circuits 30A and up, the safety standards are more stringent.

> The NEC (and related fire codes) don't apply to supply cords of
> appliances in circumstances such as OP's PDU.
> 
> The modification cancels the UL certification. If you have an external
> requirement to use only UL certified components then you can't make
> any modifications no matter how obviously safe they are.
> 
> By the way, you either don't have that requirement or you're breaking
> it. Your custom network cables are not UL certified.

There is more to safety than just being "certified".  Acting in ways
that /actually/ improves safety (if you are allowed to) is important.

This isn't just black and white.  Safety, like security, isn't
absolute.  Both benefit from defense-in-depth, and both require
compromise to balance safety vs. convenience.