I've had a compressor for over a decade, but I've only had air tools (impact
and ratchet, also nail and brad guns) for a couple of years. Makes working
on the car _so_ much easier, I can't believe it took me so long to get them!
On Sun, 25 Jul 2010 06:06:44 +0000 (UTC), Elmo wrote:
Here's the summary after reading all the posts, especially djb's (Dave
Bot..o perhaps?) posts.
1. The BEST approach is, all agree, to replace the NEMA 10-30R dedicated
dryer receptacle and 30 amp breaker with a NEMA 6-20R and a 20 amp breaker.
2. However, the use of a well-made adapter will be just as safe and
"compliant" to code, for temporary use (e.g., once every few months for a
3. The two 120V hot wires match up one-to-one; what doesn't match (at
first) are the two inconsistencies (a) amperage, and (b) ground/neutral
4. Taking amperage first, the 30 amp circuit is protecting the house
wiring, not the load. The 15 amp load will not cause a safety hazard to the
house wiring. The load has its own overcurrent protection on the motor.
5. Taking the contentious ground/neutral situation next, djb summed it up
best by clarifying the W wire in the grandfathered NEMA 10-30R receptacle
is a ground for the 240 volts of the compressor. So it's a one-to-one match
of the NEMA 6-20P plug ground to the NEMA 10-30R receptacle ground (via the
6. If we were to plug in a non-existent dryer, then (and only then), would
the NEMA 10-30R receptacle ground wire be also carrying dual duty as the
110 volt neutral (for the dryer 110V circuitry).
In summary, it appears, as long as my adapter is well made (picture of it
below), it's safe (even safer than plugging in a dryer) to plug in the cord
that I made.
A picture of the adapter cord and compressor is here:
On Jul 25, 1:06 pm, Elmo <dcdraftwo...@Use-Author-Supplied-
That is seriously the STUPIDEST thing I have ever seen
made out of electrical components...
You don't know how to put a cord end on a cord ?
Also, you could CUT the pre-made ring terminations off
of the dryer cord you purchased and used wire nuts to
make pigtails that would have fit the screw terminals
on the side of that outlet you are using...
Just because you have made something that provides
power doesn't mean you have done so properly or
On Sun, 25 Jul 2010 16:25:57 -0700 (PDT), Evan wrote:
Thanks for the advice after looking at the pictures of the adapter.
You're the only one to comment on the pictures of the adapter.
The ring terminals caused no problem; and certainly the way I did it is as
safe as any other method ... but you mention the strain relief???
Do you have a picture of how it should be done if the way I did it is
either improper or unsafe?
The only thing I can say is what has already been said. If you have
to ask these questions you should not be doing this job. This is
something left for the professionals.
Consider what could happen to your family if you assume wrong...
You'll shoot yer eye out, kid?
Three wires is pretty hard to screw up. The only thing is that the
dryer/range plug will have too big a breaker, and if the compressor
overheats, it won't pop off in time to save it.
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On Sun, 25 Jul 2010 15:45:35 -0400, Stormin Mormon wrote:
I read everything stated in all the helpful posts, and I only have two
things that I'm not sure of at this point, neither of which were questions
1. The 30-year old Craftsman compressor (model 919.176940, nameplate says
240 volts, 15 amps) certainly uses two hot wires ... but since it's using
the third (green on the compressor, white on the adapter) wire as a ground,
I guess it's really not TWO phase but really one phase.
Is it in actuality just a one phase two hundred volt motor?
2. Since the garage dryer receptacle is just on the other side of the main
panel, I assume it's connected to the main panel; but I need to check. What
I'll do, before plugging in the compressor, is stick a DMM into it and then
hit the breakers.
Is there any other way to tell that you're NOT on a sub panel?
On Mon, 26 Jul 2010 22:34:40 -0400, firstname.lastname@example.org wrote:
I tested it on the main panel and the power to the 240 volt receptacle
switched off when I hit one of the breakers on the main panel.
Yes, I have multiple sub panels. The house has had multiple additions by
previous owners. In fact, the actual dryer is in one of those additions,
so, I suspect (I didn't check) that it's on a sub panel.
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