Acquired a PDP11/44, but missing M7095

From: Eric Smith <eric_at_brouhaha.com>
Date: Wed Dec 11 20:13:01 2002

Tony wrote:
> (2) I was under the impression that US dryers, while using 230V for the
> heating elements, used 115V for the timer. And that US domestic mains
> was a centre-tapped (The tap being called 'neutral') 230V supply.
>
> In which case, if there's a neutral feed to the dryer socket which can
> carry the same current (20A) as the 2 live feeds (one from each side of
> the mains), then you could run the 11/44 between one live feed and
> neutral. This probably breaks code in a dozen places, but....

US residential wiring normally does use 240V split phase, but it is
uncommon for there to be four-conductor receptacles with both hots
(for 240V), the neutral, and the ground (e.g. NEMA 14-20R or 14-30R
receptacles for 20-amp and 30-amp circuits, respecitvely). Instead, a
common outlet for a clothes dryer has only three conductors, with two hots
and ground (e.g. NEMA 6-20R or 6-30R receptacles for 20-amp and 30-amp
circuits). Older homes might have a two-wire receptacle with no ground,
such as NEMA 2-20R or 2-30R, but this is probably not allowed by code any
longer.

Thus a typical US residential clothes dryer outlet can't be used to
directly power 120V equipment.
Received on Wed Dec 11 2002 - 20:13:01 GMT