Hydro Quebec Flex D Rate - Controlling Clothes Dryer with Insteon EZIO relay

We're just over half the peak demand season in Quebec, so far, so good. Will write up some articles on what I've done so far. On one demand management period a few weeks ago, someone in the house started the clothes dryer, I caught it after it had been running for about 10 minutes. One of the problems with the whole energy management / peak demand implementation is that it is difficult to get everyone in the house on the same page. I understand that at $0.50 per kW-hr - running the dryer for an hour ends up being an expensive proposition. It's harder to get the two 12 year olds in the house to understand. 

LG Clothes Dryer - Cover Off, Control Board back left of the photo. Relay will go close to control board

For avoiding future problems with the dryer, I decided to implement an interrupt to prevent the dryer from starting during a peak demand event. We have an LG dryer with an electronic control board. I didn't want to get into switching the power feed to the dryer - it's a large circuit. I decided to try interrupting the door open switch, effectively putting a second switch (relay) in series with the door open switch. 

Opening the cover of the dryer exposes the wiring and control board. Cut the power before opening the dryer cover for obvious reasons. The wiring diagram was attached to the inside sidewall of the dryer, and still quite legible. 

LG Dryer Wiring Diagram

The dryer switches 120V (one leg of the 240V), and it switches the connection to neutral. When open - it provides the neutral connection for the lamp inside the dryer, causing the lamp to come on. When closed, it provides the neutral connection for the control board. I decided to interrupt the neutral connection to the control board, in a fail safe fashion. My relay will be normally closed on the neutral circuit to the control board, so that if there is no control system, no connection to the relay power - the dryer will function normally. The interrupt feature will require 24VAC from my control system. 

Wiring in the relay with a relay base was quite simple - 4 connections. 

Relay with base installed on a short braket - no interference with top cover

The wire to the control board was a yellow wire according to the wiring diagram - very easy to identify. I simply cut the wire, crimped in two extensions to take the connection over to one of the relays normally closed pair of terminals. I use heat shrink crimp connections for a neat installation.

Connections made on the NC relay terminals - interrupt yellow wire (neutral to control board)

I ran a control wire down into the basement next to the dryer vent line - very easy in my case - and over to an automation panel where I had a pair of existing Smartenit EZIO 4x2 Insteon relays. I just selected one of the relay output terminals, and used 24VAC from the transformer in the cabinet. When going through the dryer case - I was careful to run the cable through a rubber grommet to avoid any shorts in the future, and ensured my cables were well attached to the dryer frame with zip ties. 

I just finished testing the connection. It works perfectly. When interrupted - the electronic control panel stays powered up, all the control lights are illuminated, but when you press the start button, nothing happens. The control board thinks the door is open and won't initiate the drying sequence. All good. This project was surprisingly quick and easy - took about 2 hours in total. Feel free to ask any questions down below.