[gyronikeleg]

Hello All,

I just purchased and finished setting up my PCNC 770 in my garage. It has been a good experience so far and I am learning a lot, as I am very new to machining.

The problem I am having is that I only have so many outlets in the old garage in my house that I rent. I have to plug in the 770 to an outlet that is nearest the mill that is a GFCI outlet. The mill keeps tripping the outlet when the spindle is running.

I have other outlets in the garage, one is a 110V outlet and one is a 220V 20Amp washer/dryer outlet. I have received quotes from electricians to run a dedicated circuit but it is very pricey for such an old house.

Can I just run an extension cord to the mill? Is there any danger in changing the GFCI to a regular outlet? Any ideas on how to solve this cheaply?

Thanks!
Greg

[luv2ride]

How old is the GFCI receptacle? I had one go bad in the house and replaced it, no issues since. What size is the wire to the receptacle? I would think it would handle the 770 needs.

[gyronikeleg]

Its an old house, but the GFCI looks pretty new. Not sure, but I can try and find out. The wire size is 12/2, when I spoke with an electrician he said that would be large enough for 115v 15amp load.

I guess I should have also specified that the outlet I am using is wired to the GFCI outlet that is tripping. I am not actually plugged into the GFCI outlet, but I am plugged into the one run from it.

Hope I explained that clear enough

[Crashbox]

If you have 12/2 wire supplying the branch circuit in question, it should be good for 20 amps; 14/2 is only good for 15A. If the circuit wiring is quite long you can get significant voltage drop which can be an issue even with properly-sized wire (probably not an issue here)...

[kstrauss]

You mentioned that there was also a dryer outlet in your garage. Is this a 3-wire or a 4-wire outlet? If it is 4-wire then it can be used to provide two 110 volt outlets. Use the ground plus red and white wires for one outlet and the ground plus black and white for the other outlet.

[RussMachine]

Just swap out the GFCI outlet with a single 120v outlet.

[gyronikeleg]

Russ,

I considered that, I know it is a violation of code, but not really too worried about that. Ha.

Is that safe to do?

kstrauss,

I am not sure, not too knowledgeable about electrical wiring. The connectors for that outlet are the large circular 3 prong connectors.

If I were to change out that outlet, would I have to make changes to the breaker as well?

[Al_The_Man]

Are you sure it is three prong plug? Generally if it is a dryer it is 4 pin, GND L1,L2, and Neutral.
If it is three then probably 240v only and no neutral.
If you unscrew the plate, turn the breaker off first and see if there is an unconnected neutral inside.
Al.

[kstrauss]

If you don't feel comfortable doing electrical wiring then pay someone who knows what they are doing!

That said, there are numerous online links that describe what needs to be done. For example, see DIY 20A 110v outlet from 220v dryer plug

[inov8r]

Just swap out the GFCI outlet with a single 120v outlet.

This is a no brainer, RM is right! You have to change the receiptical to a sideways prong 20 amp anyway. Piece of cake. Turn off the breaker and get to work. Also it is right in the Tormach info that it won't work on a GFI. Another thing, I don't know why they put a 20 amp plug on The Tormach 770 cord, because it is only 14 gauge. Kind of deceiving. So a 15 amp breaker and circuit is adequate.

[gyronikeleg]

Prime Generator Adapter, 2 ft 20 Amp Twist-to-Lock - Walmart.com

So this looks like it would be the correct adapter. I think I may end up using this to plug into my dryer outlet.

[Al_The_Man]

If you replace the outlet with a 15a/20a outlets you should by rights change the dual breaker sized for the predicted load, 20a max.
Al.

[inov8r]

You are nuts to mess with the dryer outlet. That is MHO. Your regular 120 outlet is all you need! If you are not careful you are going to introduce your new mill to 220 volts and it is going to respond with the release of lots of magic smoke and sparks!!

[gyronikeleg]

You mean plugging in an adapter or rewiring the dryer outlet is nuts?

[inov8r]

I just think your regular plug without the gfi will work fine. The dryer doesn't have gfi so what would the difference be? Other than messing with 220 and running a huge risk of damaging your mill or dying. The manual does say a 20 amp circuit is required, but then they put a 14 ga cord on it. That suggests to me that if the machine actually pulled 20 amp it would have a 12 ga. cord. So as an engineering margin they put a 20 amp plug on it. If it blows a 15 amp breaker, no big deal, then you know you need to do something else. You probably have 20 amp breakers in your panel anyway especially if you have 12/2.

[Al_The_Man]

Proper grounding can eliminate the need for GFI, these are often used in high risk portable conditions for implements that are double insulated and have a 2 pin prong plug.
A dryer outlet has two 120vac conductors WRT neutral, plus ground.
There are a few options of replacing the dryer socket, a dual gang outlet socket/plate can replace the dryer plug and change the 30amp dual breaker to dual 20a or 15amp.
Al.

[matthew798]

I just wanted to mention that you probably shouldn't try to do it yourself. Mains, especially 220v can kill you in a heartbeat. I have 3 years of training in electronics and mains still terrifies me. That's the way it should be.

Be safe!!