Router Table Electrics and Wiring a Contactor

Now that the frame of the router table is built it’s time to start plumbing in the electrics. As with the rest of this build I’ve gone a little bit over the top and installed an industrial sized contactor. Over all I’m mostly happy with the finished product but read on for details.

For any fixed piece of machinery like a router table you really should have a no volt release (NVR) switch to prevent dangerous restarts – essentially if power is cut to the machine for any reason you want it to not restart until you press the on button again.

For the home shop there are is a wide selection of NVR switches available from all the usual suspects. For example here’s one from Axminster, a KEDU KJD12, that I use on another project I built a while back. These NVR switches are fine for light use and reasonably small motors (up to maybe 2kW) but if you push them with heavier loads over a longer duration you’ll probably find they fail.

In an industrial setting where motors are generally much larger starting is a bit more of a challenge and there are several methods used. The simplest method is called direct-on-line and it is the one I’ll be using here. With direct-on-line switching the motor is simply connected straight to the power through a contactor. Often, but not always, a direct-on-line motor starter will include an overload sensor which can cut power to the motor if it detects a problem.

Direct on line starters are good up to medium sized loads of around 4kW single phase so should cover the vast majority of machines in the home shop. Since the power is supplied through a contactor it also acts as a no volt release switch and being an industrially rated device it should last a lifetime on a home machine.