L6-20P -> L6-30R

Wed Mar 19 13:49:08 UTC 2014

On Tue, Mar 18, 2014 at 07:09:49PM -0400, David Hubbard wrote:
> I've had to do that before; provider gave me a 208v/30a circuit and I
> already had a power strip I wanted to re-use that had a corded L6-20P
> connector on it.  I purchased a L6-30P plug / L6-20R receptacle adapter
> from http://www.stayonline.com/nema-locking-6-30-amp-adapters.aspx
> They're only $25 and they ship overnight if needed.  They have one foot
> cabled versions of the same thing too if you have tight working space
> and there's not enough room for both connectors back to back; works as a
> strain relief too so maybe that option is better regardless.

This is not really a safe thing to do unless the "adapter" has a 20A
circuit breaker as part of it, or if you change out the upstream
circuit breaker from 30A to 20A (and hopefully clearly mark the outlet
as such).

> If you're trying to go the other direction, plugging an L6-30P into an
> L6-20R 20 amp circuit, that I'd recommend against because it never fails
> that someone says hey, 30 amp power strip, let me plug some more stuff
> into it not realizing it's on a 20 amp breakered circuit, then all your
> stuff goes down while you try to find the facility staff to reset the
> breaker.

Going this way is safe, but as you say, you can only draw 20A
(actually, you can usually only draw a derated 80% of that, so 16A).