I have a 240v 30 amp heater that I want to hook up a 120v push button timer to (neutral required for timer switch). I bought this RIB01P30 relay but am having some trouble wiring it up. This is the original post I was referencing but the wiring for the relay I got does not have any of the common wires. The link to the relay has a wiring diagram but could link a photo here somehow if that's helpful! @ThreePhaseEel suggested I post a new question. Thanks in advance!

  • 240V means you have two 120v wires, so you need to switch them both. Your chosen timer can only switch one.
    – Ruskes
    Nov 21, 2022 at 2:38
  • Do you have a separate 120V circuit for the timer, or do you have a neutral with your 240V circuit instead? Nov 21, 2022 at 2:43
  • I have both readily available. I think I'd prefer to use the separate 120v circuit though if it's an option based on the location though. Nov 21, 2022 at 13:33

2 Answers 2


"Don't make it harder than it is"

The key is -- don't get confused and think the coil is related to the power contacts in some way or another. It's absolutely not. The coil can be powered from a different circuit, a different voltage - heck, even a different electric service. That's because the coil and line contactors do not have any wires in common.

Since you have a 120V coil, you can simply grab 120V from any convenient circuit (however, if the bathroom receptacle circuit powers more than one bathroom, you cannot grab from that). The 120V hot+neutral goes to the line side of your smart timer, then the load side hot+neutral goes to the relay COIL.

That's it. The control circuit wiring is done.

Separate from that, you bring the dual 240V hot wires to the relay, and attach to the relay (one of each color of the large wires). Then, you take your "onward to the heater" wires and attach to the other one of each color. According to its instructions.

The relay 240V wires do not connect to the coil wires in any way.

  • Thanks for your reply! I think I'm starting to wrap my head around the idea of the relay wiring. I made this sloppy diagram to confirm my understanding: freeimage.host/i/HJsqzlt. So in essence, when the relay is "powered", meaning the load side of the timer is activated, it will open the 240v circuit, right? And since I only have a single hot wire to my heater, then I'd just use a single pole of the relay for the 240v hot and load (to the heater) if I'm understanding this right. Couple of questions though: Nov 21, 2022 at 23:36
  • 1) do I attach the hot (load) red wire from the timer to one of the blk/wht 120v wires on the relay, and the neutral wire from the 120v to the other blk/wht? Nov 21, 2022 at 23:39
  • And by "So in essence, when the relay is "powered", meaning the load side of the timer is activated, it will open the 240v circuit, right?" what I really meant to say is that it will "close" the circuit (I think). Confusing my terminology there. Also, I answered the second question I had myself, which was whether NO was the right type of relay (again, confusing open and closed). Nov 22, 2022 at 0:07
  • 1
    @Joshua you are confused about how 240V works in North America... here's a primer. Both wires to your 240V are hot and it does not take neutral. Other than that the drawing is spot on, including combining the grounds and not the neutral. Nov 22, 2022 at 1:06
  • 1
    @Joshua yes, and using white wires appropriately (e.g. not using it for a hot wire unless there is no other choice). Nov 22, 2022 at 1:39

This is fairly simple

The RIB01P30 is, fortunately, a fairly easy part to wire up. For your application, once the relay has been mounted to a knockout on the box:

  • The incoming 120V hot gets connected to the timer's HOT wire
  • The incoming 120V neutral gets connected to the timer's NEUTRAL wire as well as one of the white/black (coil) wires from the RIB01P30
  • The timer's LOAD wire gets connected to the other white/black (coil) wire from the RIB01P30
  • One of the incoming 240V hots gets connected to a brown wire from the RIB01P30
  • The other incoming 240V hot gets connected to an orange wire from the RIB01P30
  • One of the load wires for the heater gets connected to the other brown wire from the RIB01P30
  • The other heater load wire gets connected to the other orange wire from the RIB01P30
  • And finally, all the incoming grounds from the cables get connected to each other, the grounding pigtail from the box (if present), and the grounding terminal on the timer.

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