I got a 220v Shop Fox DC remote control, the $38 stuff from Grizzly.
It is not a long ranger. On curiosity I opened up the unit and the
first thing I noticed is that one of the phases going straight to one
outlet pin of the NEMA 6-20 receptacle. The other phase is controlled
by the relay and a small PCB.
So, when the unit is in OFF position but powered by the mains supply,
one of its NEMA 6-20R is always live! Before hooking it up to
anything else I checked my suspicion and it is true. Between that
live phase and ground I got 120v as expected. Between both the phases
there is 0v when the unit is in OFF position.
When the DC is turned off by this remote I dare not touch any
electrical part of that motor...even though the box clearly says it is
"remote control switch". My idea of a switch was a little more on the
safer side. How would you like your table lamp to be on live side of
Is this a norm for 220v stuff or am I missing something? Are all
remote controls for 220v DCs like that? I believe PennState has it
Yes, it would be best to switch both legs on 220 volt, but it is not as
unsafe as you fear! If properly wired your motor's frame is wired directly
Your home air conditioner probably has a single pole contactor running the
compressor, very typical.
I would not worry about it.
interesting find, kp. I use Shop Fox 110V remotes and once
in a while they turn on by themselves. I got a replacement
for one that had a tendency to turn on accidentally way too
often. I use one for a shop vac and one for the DC. It's a
bit unnerving to hear the whine of either in the middle of
the night! :) Morale of my short story is never work on the
equipment while it is plugged in to the remote.
On 13 May 2004 20:24:13 -0700, email@example.com (kp) wrote:
I'm not sure about other remotes, but in any case, I don't think I would
ever touch the "electrical part" of any motor while it was plugged,
regardless of whether it was on the downstream of a switch or not.
One thought, check out the switch on the DC -- does it just switch one
phase or both?
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