Monitoring an Emergency / Standby Generator

Hello. We had a Briggs & Stratton (“B&S”) emergency standby generator installed a year ago. B&S sells an expensive monitoring solution, but all I want to know is when the generator starts and stops. It runs a very brief weekly exercise cycle (20 seconds) and a longer exercise cycle in Spring and Fall (20 min). The short cycles don’t warm the engine up thus avoiding condensation which is the enemy of engines.

Another post suggests using a vibration monitor on the generator. That’s a good idea, but it is susceptible to wind and hail and may not work well when the temperatures drop below zero.

The generator company proposed a simple solution. Put a 12 Volt relay on the power to the solenoid that opens the natural gas fuel valve. Then have Z-Wave read the Normally Open dry contacts on the relay. When the contacts go closed, the generator is running. I use the dry contacts in an Aeotec Zwave Door/Window Sensor to monitor my garage door open/closed state. I could use that device or the Aeotec Dry Contact Sensor Gen5 to monitor the relay contact state.

I use a similar setup to monitor AC Power failure and restoration in the house. A 12V step-down transformer powers 12V relay. A Z-Wave sensor monitors the dry relay contacts. When the power goes out, the relay goes open and I get a SmartThings alert of the outage.

The generator is about three feet from the house and I’m thinking of putting the sensor in the warm house and running wires out to the generator (in flexible conduit). The relay could be either in the house or in the generator housing.

Has anybody monitored their standby generator this way?

I used a Samsung multi sensor in my old Gen for years. The trick was to put it inside the generator to protect it from the elements. I never had any issues with the temperature going to low. I have had winters that went down to – 20. This is the easiest way.

This will also work but require a little more effort. I would just wire this up inside the generator housing and skip the conduit.

Or is it running? This check only tells you the gas was turned on–it does not tell you the motor is running or the generator is putting out any power.

Are you comfortable tapping into the generator output, prior to the transfer switch? That would work with your similar setup for house power (12v supply & relay). Another option may be checking out the a schematic for the transfer panel (either inside the unit or an online reference) for test points that indicate actuation of the transfer panel and using those to actuate a contact sensor.

Disclaimer: if you’re not comfortable working with the equipment, don’t do it–for safety, your local electrical code, and warranty reasons!

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