Tuesday, January 4, 2011

Wiring the SawStop and Router Wing

I previously gave a tour of my router table installed in the right extension wing of the SawStop PCS.  Also showed how I made the overhead dust collection pipe with a light.  Thing is, between the saw, router, and light, that makes for a lot of power cords going to the machine.  Anyone who knows me knows I don't like cords or cables since I can be amazingly clumsy around them.
I recently took a couple weekends to install conduit in my shop in order to drop a number of 110V and 220V circuits; yes! finally I can run my drum sander without a long extension going into the living room.  I'm not kidding.
One goal of that wiring job was to consolidate the power cords going to the SawStop, router, and light into a single feed.  I'll walk you through what I did in case you find it useful for your situation.  Note that this doesn't presume a SawStop saw; any 220V saw could use this setup.

I'm not an electrician, though I'm comfortable wiring plugs and sockets like this. I'm explaining what I did. If you like the idea, feel free to research it further or hire someone to do similar wiring for you. If you blow something up, well, then, that's a bad start to your day. And it's also not my fault.
Okay, with that out of the way...
Shown here is the drop for the SawStop/Router/Light that we'll now refer to as shtuff.  The drop has 4 wires: ground, neutral (white) and 2 hots (red).  These come from the subpanel I just installed (and will document!).  The two hots come from the two hot buses of the subpanel, neutral from the neutral bus, and ground from the grounding strap.  Even if you are coming from a main panel (not a sub panel), you will need all 4 wires.  The reason I am specifying this is that people may read that a main panel ties ground and neutral together.  You might therefore conclude that you can just run one wire for both.  That assumption would lead to you having a bad (possibly short) day.  In my forthcoming posting about wiring the shop, I'll explain that in much further detail.
The image to the left was actually meticulously drawn on the computer then run through a filter to look like I scribbled it on paper then scanned it.  What this shows is how you form a 110V circuit or a 220V circuit from the two hot and one neutral bus in a panel.  For a 110V circuit, you take a wire from either hot bus and the neutral (neutral goes to the wide blade of a socket; hot to the narrow blade).  For a 220V circuit, you take wires from both hot buses; there is no neutral involved.  Naturally, all receptacles require ground.
The fourth plug configuration in image shows the configuration we are interested in.  Basically all 4 possible wires from a panel are brought to the receptacle.  In the drawing, I showed the plug configuration for a 30A circuit although I ended up using a 20A twistlock format you'll see next...
The 20A twistlock socket is shown to the left with the plug to the right.  I also bought 10' of 4-conductor stranded 12ga wire.  I need 12ga for the current load; four conductors for the four wires (yes, ground should never conduct but "extension cord" wire is ordered this way); stranded because it is more flexible for making this pigtail.
The socket has 4 screw attachments for wiring.  This first side shows a brass screw and a silver screw.  Brass always gets a hot so I'll wire a red hot wire here (either one).  Silver always gets a neutral (think of silver as whitish so it gets the white).  I'll wire the white neutral here.
The other side has the other brass screw for the other red hot wire as well as the ground, which is always green.
Here's a wiring diagram from Ugly's Electrical Reference.  The pencil points to the L14-20R configuration that is the twistlock shown earlier.  I wired the twistlock socket according to the screw colors discussed previously.
Now, on to the pigtail for the shtuff.  The idea is to have the one cable go to the saw and break out our power requirements.  I stripped the insulation from the 4-conductor cable per the plug specs (read the box to know how much insulation to strip and how much to strip from each wire).  Push the wires through and screw them to the correct plug blades.  The plug comes with documentation.  As a hint, that "hot to brass; neutral to silver" storyline comes into play.
The other end of the pigtail goes to a metal 2-gang box.  One side of the box will have a 20A GFCI 110V duplex socket.  The other side, a 20A 220V socket.  The shtuff will plug directly into this box mounted to the router's dust box.  Here you can see the box wired up.  I should have taken more step-by-steps of producing that, so here's some narrative: the GFCI plug is wired with one hot to its brass screw, neutral to the silver screw, and ground to the green grounding lug.  The 220V socket gets a hot to each of its brass screws and ground to the grounding lug.  Notice that I'm not naming wire colors.  The four conductor "extension cord" has a white, black, red, and green "conductor" inside.  I wired neutral to white, ground to green, one hot to red, and the other hot to black.  Likely this will be your case as well, but it is also possible to get other combinations; keep track.  Note that red or black wires are assumed hot unless otherwise labeled in household wiring.
At this point, the wiring is done.  Reverify.  After turning on the breaker for the twistlock receptacle, I used a multimeter to verify all the voltages were correct.  After wiring the pigtail, I verified continuity from the plug blades to where that current should go; I also verified that all the other places did not have continuity.  The multimeter shown here is a $4 meter from Harbor Freight; for continuity, it works well.  It isn't a Fluke, but if you screw up and burn it out, it's basically a Venti Soy Latt√© out of your pocket.
Lastly, I needed a cover and the configuration with a rectangle and a round isn't typical.  I took a plate with a rectangle and an old-style flip switch opening (small rectangle) and drilled a hole for the round.  This picture is from me doing it to a different cover for elsewhere, but gives the idea.  I screwed a single cover with a round to the cover to drill then used that hole to place a 35mm hole (Euro-hinge Forstner bit) right where I needed it.  Couple seconds of filing to get a perfect fit.
Here's the box surface mounted to the dust box in the router extension wing.  The 110V GFCI receptacle has the router and light powered while the 220V receptacle has the SawStop powered.  All cords are strapped and tucked away under the rear fence rail so nothing for me to trip over!
While this whole process may see long and laborious, it really isn't.  Whenever you run a 220V line for your saw, run a neutral as well and you can easily do this wiring.  Also, this wiring isn't some freak of nature: this is how older dryer drops were wired and how generators are wired.  That I broke it off into separate receptacles on the saw itself is likely the only unique thing.
Here's a way you can save money and time doing this.  For the pigtail, I bought a twistlock plug and the 4-conductor "extension" cord from a commercial electrical supply house.  It was, ahem, pricy.  For half the price and a third the effort, you can buy a 12ga 25' generator extension cable from Harbor Freight shown here.  Cut the cable however many feet you need from the plug-end of the cable.  This is molded cable so stripping the outer insulation back is tricky work with a cutter, but I've done it to literally a dozen extensions.  Once the inner insulated wires are revealed, you just run them to the box on the saw.  I actually would have preferred this route had I realized it first because I like their yellow/black extensions (highly visible); molded insulation like that doesn't get twists in it so easily; the plug is molded onto the wires... no screws and half the size.  Oh, and I paid double for just 10'!
The picture also shows the cover of Ugly's Electrical Reference.  Definitely recommended, but only if you need a reference; it isn't a how-to.


  • Anonymous said...

    An excellent explanation on wiring! With my understanding of electrical wiring I wouldn’t attempt installing a ceiling light fixture, but after reading your article I might even attempt such a thing as you’ve explained. I also appreciated the cost saving comments as well. I’m looking forward to a write up on your subpanel installation.


  • Michael said...

    Great way to reduce cords across a shop. I too have a similar saw/router setup and would like to wire it like you did; however, i'm a bit confused (easily done at my age lol). I count 2 hot wires going into the duplex box but 3 connections. Is one hot pulling double duty...connected to the 110 and 220? Thx for a very informative blog and youtube site.

  • HalfInchShy said...

    Hi, Michael,

    What goes into the box on the saw station is a pair of hots, a neutral, and ground. The 220V socket gets the two hots on its terminals as well as the ground. The 110V duplex socket gets one of the hots (either one) to its hot (the brass terminal) and the neutral (to the aluminum terminal) as well as ground. All you're doing with the 3 conductor + ground wire going to the saw station is bringing the rails at the subpanel out to the saw to make your connections there.

    If you mean "double duty" because it goes to two sockets, yes, and that's normal. In your home's wiring, a hot and neutral go to one socket then a cable runs from that to the next to the next and so on in a string. You are basically creating that inside that box.

    Very very handy; when I shoot video, I often unplug the light that goes above the saw to plug in a softbox diffuse light for the camera.

    If the following doesn't make sense depending on your electrical knowledge, just ignore it: it describes a different wiring scenario you could use, but don't have to use:

    In my case, the 110V duplex socket is a GFCI protected socket (a master); that's always a good idea. If instead you used GFCI-protected breakers in your subpanel, you wouldn't (can't!) use GFCI sockets (double protecting doesn't work properly).

    If you had a GFCI-protected breaker on that circuit, you could even split the 110V duplex socket. There's a bridge between the two sockets that can be removed. Remove it on the hot side (brass side). Now run one hot to the top socket, one to the bottom. Neutral still goes to the other side as well as ground to ground. Now what you've done is put the two sockets on opposite rails better balancing current in the neutral line. Isn't a big deal, but thought to explain it.

  • Michael said...

    Thanks Paul. Makes perfect sense, especially after reading your blog about adding a subpanel to your garage.

  • Anonymous said...

    I went with your 4 wire setup on my band saw. I replaced the previous setup which brought 3 wires to the saw. I wired the 220 direct inside the duplex box, no receptacle, and put in a 110 GCFI receptacle like you suggested. One of the hots goes direct to the saw and one goes to both the saw and the plug, neutral goes to 110 and ground goes to both. For GCFI to work properly, does the hot that goes to the saw have to go thru the load on the GCFI like chaining 110s or can it be pig-tailed? I went with pig-tail as I don't see how GCFI works in conjunction with 220 because there is no neutral. Your thoughts would be appreciated.


  • HalfInchShy said...

    Hi, Tim,

    Sounds like you have it correct. The wires going to the saw just continue on to the 110V GFCI receptacle (a parallel connection).

    There are 220V GFCI receptacles and you could install a plug on your bandsaw, wire a 220V GFCI receptacle and plug it in. I didn't do that and it isn't required here.

    The way GFCI works is to monitor the current in the two current-carrying wires (the two hots for 220V or the hot and neutral for 110V... yes, neutral definitely carries current; it's poorly named). The current in one wire should always equal the current in the other. A GFCI receptacle monitors that and trips when they are not equal. When they are not equal, the current is going somewhere and that somewhere is ground, hence a ground-fault.

    About your question about "does the hot that goes to the saw have to go through the load on the GFCI". No, definitely not. The current source attaches to the GFCI's "line" side and your protected devices are plugged into the "load" side; you don't want any part of the wiring skipping over from "line" to "load" side.

  • Anonymous said...

    Hi Paul. Nice n informative blog, I have a query regarding 220v outlets. How many 220v duplex outlets we connect to a single circuit or to a breaker of 20A.?and will the size of wire will be same for 110v and 220v.? I.e 12awg.