DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Electrical (
-   -   Wiring 240v pump to generator - URGENT (

Benchr 12-19-2006 12:43 PM

Wiring 240v pump to generator - URGENT
Hello, writing from the Pacific Northwest, where we have been without power for 6 days now... I am so glad we got the portable generator and transfer switch.

However, I need to run my septic pump off my 5500w generator as the pump tank is filling up. I only need to run it for about 2 minutes a day until power is back, so this is ultra temporary.

It appears to be a 240v pump according the docs I could find, and it is connected to a red and a black wire (white wire is not connected to anything). It has a doubled-ganged breaker. However, I would like to confirm that my thinking is correct here and that this means it is 240v. My house was built in 2003.

It is not possible to buy the 4 prong generator plugs at this time due to everyone being sold out. However, I wired up 2 regular 120v plugs (rated 15A) together to plug into the generator's console. Using my meter I can measure ~240v between the two black wires and ~0v between the 2 white wires. So I connected the white wires together and connected the 2 black wires to the septic pump (which is unhooked from the house wiring to be safe). I added a heavy duty switch to interrupt one of the black wires.

Now my 2nd question is which black wire is the equivalent of "red" in my house wiring? If I guess wrong, will the pump be damaged or run backwards? ??

Thanks for any assistance or reassurance I've done this right.

Christopher 12-19-2006 01:27 PM


Nothing you do will result in the pump running backwards, the pump motor is internally wired for one direction only (this is only an issue in 3-phase equipment).

Provided the circuit breaker for the pump is 20A or less you should not have difficulty provided the generator will tolerate the pump's starting current.

You have determined that there is 240V across two black wires. As far as the pump is concerned, these two source line wires are interchangeable.

As long as the pump starts quickly there will be no damage. You can measure the voltage (carefully!) while the pump is running, allow only a 1-second dip while starting. If the generator fails to start the pump, you will need to borrow a bigger generator from a neighbor once a day.

Be safe and let us know how things are going for you.


Benchr 12-19-2006 04:00 PM

This worked wonderfully, thanks for the help!

The generator has a surge rating of 8800W, and the pump control circuit has a warning which says the pump must be 15A or less, so I don't think there was any lack of power to start the pump.



Christopher 12-19-2006 04:35 PM


Glad to have helped you with a timely solution. In South Florida, the biggest problem during a power outage is a stranded "lift station".

Remember, keep the generator away from any open windows or doors.


Sparky Joe 12-19-2006 05:50 PM

That'd be funny if it started pumping poop back up into your house though

All times are GMT -5. The time now is 07:03 PM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1