# Question about 220 and 110 wiring runs.



## NevadaBlue (Apr 7, 2012)

I am in the process of running a 220 line to my new mill. I am using 10/3WG cable from the breaker box to a disconnect at the mill. The mill is a Grizzly 0705 and only requires a 15 amp service at 220 volts. 
What I want to do is split a couple of 110 volt circuits out at the disconnect box, for lights and such at the mill area. Can I do this as long as I don't exceed the rating of the breaker and wiring? Or, should I just do the extra work and run a dedicated 110 volt line?


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## pdentrem (Apr 8, 2012)

Will you be using 15 amp fuses or will they be larger? 10 gauge is rated 30 amp max.

Will you be using 14 or 12 gauge wire for the 120 line?

What is the local code for this application in your area? In any case you can not exceed the total amps available.

I would be hesitant to split off 120 from the 220 if using large amp fuses. I would put in a small box with 2 15 amp fuses for the 120 side. You can feed that box from the 220 box. I would attempt to balance the loads between the two.


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## NevadaBlue (Apr 8, 2012)

Thanks for the quick reply. I'm using a 30 amp breaker. My plan was to split a 110 line off and use a small fuse box that I have and put 15 amp fuses in it, using 12 gauge wire. The little fuse box is a disconnect too. I'm in a very remote area and I would bet that nothing for miles is to code. I try to make a safe installation, but I've never seen this done. I guess I'm being lazy, it would be best just to run the 12 gauge from it's own breaker in the main box. I have plenty of breakers open.


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## DMS (Apr 8, 2012)

If you stick to 15A, you will be fine with the breaker depending on how much the lights "and such" take. If I were you, I would go for at least a 20A double pole breaker. You have already sized the wire large enough. In fact I would go with a 30A breaker. If you go with the the 30A line, I would take pdentrem's advice and add some fuses for your lights and (I'm assuming) convenience outlet. You probably want to use 12 or 14ga wire for the lights and stuff (most 110 receptacles wont accept 10ga), and if you do that, you can't (by code) connect them to a 30A breaker because 12ga is only rated for 20A, and 14ga is only rated at 15a.

If you decide to stick with the 15A (or go up to 20A) breaker in the service panel, you should be able to wire everything up with 12ga, and be alright, just be wary of this if you ever upgrade your machine and need more power, swapping in a 30A breaker is not the right thing to do at that point.

On my mill, I actually installed a small sub panel. This is connected to a 30A double pole breaker at the garage sub panel. In the panel are 3 breakers, 1 for my vfd, one for my CNC controller, and one for the drive motors and drivers of my mill. Worked out really well.

Just to add a disclaimer, IANALE (I am not a licensed electrician). I have done some work on my own house, have done my due dilligence, and passed all inspections. The main thing to be wary of is safety. Ground everything, and size your wire correctly.


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## DMS (Apr 8, 2012)

If you do add a 110 run back to the panel, you will need to (by code) run it in another conduit, or be forced to de-rate all of the wires running in the conduit. The limit (going from memory, so don't quote me) is 3 conductors in a conduit before de-rating. This is to prevent overheating. I know you said you are likely not going to have to pass inspection, but it's something to keep in mind. You're plan with the small breaker box sounds like a good one (well, obviously it would sound good to me, it's the one I chose for myself 

DMS


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## NevadaBlue (Apr 8, 2012)

Just to be clear, the 10 gauge run for the 220 supply to the mill is going on a 30 amp double breaker in the main box. It ends in a fused disconnect box at the mill. 

I think I'll just run a 12 gauge line over to the same area, from a 20 amp breaker (110 volt) so I can run my drill press and mini mill from that circuit too. Then I won't have to worry about code (it will be within if anyone ever looks) and I can run anything I have in the area that needs 110, lights and all. 

I'll post a pic when I get it completed. I need to pick up some flex conduit, I forgot that when I went to town.


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## Hawkeye (Apr 8, 2012)

You will find it much simpler to run the separate line from the main panel. As pointed out, you would have a bear of a time putting #10 wire on a 15 amp receptacle. Never run less than #10 wire on any part of a circuit that is protected by a 30 amp breaker or fuse. That includes extension cords. You might get away with it for decades, but if a fault ever occurred, the thinner wire could set the whole thing on fire before the breaker tripped. (Might not, but could - your choice.)

In a case where it was simpler to use the 30 amp 3-wire feed, you could install a small panel with breakers for the branch circuits, as DMS did on his mill. In a case where you would be the only one using the shop (only one machine running at any given time), you wouldn't have any trouble with a 30 amp load running off your small panel. The 15 or 20 amp branch circuits wouldn't be drawing any power while the big one was running.

BTW, I am a licensed electrician.


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## irishwoodsman (Apr 8, 2012)

most codes are 5 outlets on one circuit, if you are using a drop down box[220] to run mill by code you can not run anything else off of the box, this is in missouri, i have three drop down boxes on mine, 1 for welder, one for lathe and one for mill which i dont have yet and they are on their on circuit i am running a 200 amp main box, do not go lower than 10 gage or it will come back to bite you, been there done that lol:biggrin:mac Lowes has a good book on main wiring and add ons for about 20.00 its a life saver.


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## NevadaBlue (Apr 8, 2012)

Thanks guys. I was just searching for a way to keep from putting my old body up in the air in the shop. Because of the truss design of my shop, I need to run the power for this area of the shop up to the peak and back down. It is a steel frame building and the mill is out in the center. (24x24 shop my lady made me build it right)

I do have a wiring book and usually only refer to it for 3 way switches... LOL  I was just being lazy and hoping for a free ride for the 110 volt stuff. Best to just do it right.


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## irishwoodsman (Apr 8, 2012)

NevadaBlue said:


> Thanks guys. I was just searching for a way to keep from putting my old body up in the air in the shop. Because of the truss design of my shop, I need to run the power for this area of the shop up to the peak and back down. It is a steel frame building and the mill is out in the center. (24x24 shop my lady made me build it right)
> 
> I do have a wiring book and usually only refer to it for 3 way switches... LOL  I was just being lazy and hoping for a free ride for the 110 volt stuff. Best to just do it right.


  you will be much happier and safe:biggrin:mac


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## DMS (Apr 8, 2012)

Another option (rather than going all the way up to the peak of the roof) is to suspend some strut from the ceiling, and hang the pipe from there. That is assuming you don't need the space up that high.


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