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More tools in the shop #2: New Additions and Wiring for new machinery

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Blog entry by Plasmon360 posted 03-02-2018 11:30 PM 353 reads 0 times favorited 0 comments Add to Favorites Watch
« Part 1: New Larger Table Saw (Delta unisaw) Part 2 of More tools in the shop series Part 3: Grizzly jointer. »

Before reading some of the electrical work I wrote in this article, please note that I am not an electrician and have no suggestions to anyone. This post is to document my experience and is not a “how to” post.

As stated in my last post, I acquired a table saw (unisaw) which turned out to be a great deal. Following that I also got a heavy duty chisel mortiser, planer, and jointer from the same seller (they seem to be a good deal). I will write about them in detail in later posts but for now here are the details for their power requirements

Delta unisaw 36-957: 3 hp needs 12 amps @ 220V,

Grizzly G1021z 15 in planer: 3 hp needs 12 amps @ 220V

Grizzly G1018 8 in jointer: 3 hp needs 12 amps @ 220V

Grizzly floor Chisel mortiser: 1 hp works with 110 V needs 7A

All are single phase.

I have some 110V outlets (20Amp) in the garage but no 220V outlets except for cloths dryer. At this moment, I donot want to pay to install subpanel in the garage. It just seems to be too much work/costs trying to get permits/electrician etc. So I decided to use dryer outlet for running this machinery using a home made extension cable. My dryer outlet is 220V at 30A which should be enough to drive at least two of the above tools at once in an extreme case (I will be the only one person running the tools and I don’t think I will be running two tools at once).

I know dryer outlet is rated at 30 Amp, because I saw the breaker for it and it had a 30A breaker on it. The wire that connected panel and the outlet was 10-4, which meant it can take 30A and had 4 wires in it. The 4 wires being L1, L2, neutral and ground. If I am not wrong, neutral and ground are tied together in the panel. L1 and L2 are 110V AC wrt to neutral/ground but 180 degrees out of phase so the potential difference between L1 and L2 is 220V AC.

The outlet/receptacle was behind the dryer, so it cannot be accessed easily. It had three pins (one for L1 , one for L2, one for nuetra (white)l, there is no ground on the receptacle). This outlet turned out to be NEMA 10-30R. I figured it out from wiki image on NEMA connectors

After turning off the 30 amp breaker on the panel, I opened the receptacle and saw four wires and the ground wire (green) was by itself not connected to anything. This proves that it was 10-30R. I checked the resistance between the green and neutral, they were short. The ground was not connected to the receptacle housing (I think it should have been connected to the receptacle housing).

Here are some pictures of that

As you can see in the last picture the power cable on the dryer has three cables and none of them went to the chassis ground (the green nut).

So to summarize my current setup, i drew a diagram with color coding.

Powering the machinery will need a ground so I have to come with a way to get the ground connection from the outlet. In addition to this machinery, we have a electric car that we leased for 3 years. we have been lucky that there is fast charging station behind our house and it is free to use for the first two years. we go there to charge our car and rarely charge at home with 110V. We are almost at the end of first year. But after one year from now, we have to charge the car at home using 30 Amp, 220V car charging system which needs a ground. we need an outlet for that in the future, so I was planning for that too.

So in summary, I have to use the 30A 220V circuit for charging the car, drying clothes and woodworking machinery. Here are the two options schemes for wiring I came up with. I wanted to make sure at anytime load should not exceed 30 amps.

Option 1: have three separate outlets but two switches (double pole double throw) switches like these rated at 30A 220V to power one outlet at a time. In this case, one needs to just flip the switches and current will flow in only one of outlet. Choose 10-30R outlet for dryer, dryer will not have its own ground, choose 14-30R for electric car charging system (which will have a ground), and 6-30R for machinery (which will have a ground). To drive the machinery I will have an 30 foot extension cable that will have 6-30P plug on one side and two 6-20R outlets on other side. Here is the schematic for this.

Option 2: Manually changing the plug but have one outlet for all four. this will require to replace the current three slot dryer (10-30R) receptacle to four prong receptacle ( 14-30R) to a more accessible place. If I did that I have to change power cord going to the dryer from a three prong to a four prong plug. I also needed to ground the dryer (basically attach the green wire from the power cord to a grounding screw). I can also build the extension cable with a 14-30p but leave the neutral not connected. In this option, one has to manually change the plugs. Here is the schematic for this option

After researching all the costs associated with both options, we (my wife and I) decided to go with Option2. It is going to be pain in the b* to remove the plug and replace the plug. Those double pole double throw switches and outlets are expensive. I learned that costs add up very quickly when dealing with electrical hardware. I should have gone to a electrical supply place rather than big box store in the future.

All the outlet boxes are grounded. I used 10 guage THHN wire in 3/4 in EMT conduit (to future proof) for putting the new outlet. Now the outlet is more accessible to change the plug. Those 90 degree bending fitting are each 7 dollars, quite expensive. I need to learn how to bend emt to save money.

So here is the final setup.

I still need to make the extension cable which should be very simple. I will use 30 feet of 10-3 Soow cable which runs about 2 dollars a foot at big box store.

I am happy things are moving ahead.



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