Sanity Check This 240V -> 120V Wiring, Please?

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Forum topic by jonah posted 05-27-2017 11:32 PM 645 views 0 times favorited 4 replies Add to Favorites Watch
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2122 posts in 4075 days

05-27-2017 11:32 PM

Topic tags/keywords: jointer powermatic model 60 120v conversion

Just picked up a ~1970s era Powermatic Model 60 8” jointer that was previously wired for 240V. Not having 240V in my current shop, I rewired the motor (the beefy original 1HP Dayton) according to the diagram on the plate. I’m confident in that. I just pulled the plate off the switch (a Rockwell magnetic switch of unknown age and provenance), and it looks like this:

So the switch can handle 120V no problem. That’s nice to know, and saves me some dough and some time.

The back looks like this:

This wiring looks fine to me. The upper right is the hot wire from the plug I just replaced (the cord was standard 12AWG SOOW, so I just replaced the plug at the end). The lower right is the neutral from the plug. The upper and lower left go to the motor.

Before I plug the thing in and turn it on, does that all look right? I’m 95% sure, but it can’t hurt to get a second opinion from the LJ electricians.

4 replies so far

View TheFridge's profile


10859 posts in 2262 days

#1 posted 05-27-2017 11:52 PM

Looks fine to me.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View BlasterStumps's profile


1686 posts in 1216 days

#2 posted 05-28-2017 01:19 AM

What amp draw will the motor be on 120V?

-- "I build for function first, looks second. Most times I never get around to looks." - Mike, western Colorado

View Loren's profile


10477 posts in 4424 days

#3 posted 05-28-2017 01:27 AM

You have to look at the way it’s wired going
into the motor to tell if it’s wired for 120 or

With 3 wires 120 uses a hot, neutral and a
ground while on 240 the neutral wire is
a hot as well. There should be a wiring
diagram on the underside of the plate on
the motor, if not on top of it.

Magnetic switches work pretty much the
same whether that 2nd wire is neutral or
hot, so you can’t reliably say it’s wired
for 120v by looking at the switch wiring,
if memory serves.

View jonah's profile


2122 posts in 4075 days

#4 posted 05-28-2017 02:59 AM

I already changed the motor wiring. That is all set. I was talking about the switch wiring in the original post.

It’s a 1HP motor, so it draws around 10A @120V.

I plugged it in earlier and it works. Thanks for the replies.

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