Trying to calculate the cost of producing my biodiesel, so I bought a Kill-A-Watt meter. Been playing around with it some, and noticed the voltage drop quite a bit when using both the Norhtern pump and the 110v water heater element. Just for comparison, I hooked the meter up to the dehumidifier and saw a drop from around 121v down to 116v. The drop with the element & pump running was in the 105v range. I know that running low voltages is hard on pumps, so I'm a bit concerned.

Has anyone else monitored the voltage drop while running a pump and heater simultaneously? I've done this for several months, so maybe I shouldn't be concerned.

I don't think you need to worry about it unless you are running a big pump. I have been doing it
for years and running the power thru a 50 foot and now a 100 foot extension cord. Just can't turn on any big power consumer in the house. My wife has learned to ask if anything is running before she plugs anything in. Old house, and I imagine only 100 amp service at best. I draw about 14 amps with both running.

If your wire is too small, like a long run of 16 ga. extension cord, not only will you get a big voltage drop, your wiring can get hot.

If it's an extension cord, just feel it. If it's hot, you're wasting a significant amount of electricity and your risk of fire goes up. If it's hooked up pretty much straight to your house wiring (so, not a long thin extension cord), we would have a little bit different conversation.

What's your voltage with nothing plugged in?

finest regards,

troy

As Troy eluded to above more information is required. Is the voltage at your panel dropping when the pump and motor are on or are you taking the reading where the items are plugged in?
That is a significant voltage drop that I would remedy if it were in my setup, however it will not likely cause any damage. It is hard on the motor but would not likely shorten the life of it enough to matter and for the price of them who cares? There will be no issues whatsoever with the life of the heater element.
If you are not using a long cord dirty or bad connections also are a Big and common contributor to voltage drop, it may be worth your while to ensure clean and tight connections in all the terminations on that circuit right back to your panel. Once the power is off and you have your panel open it is standard practice to "re-hit" all the screw's to ensure they are tight. Heating and cooling of the conductors eventually loosens all mechanical electrical connections over time...
You dont want the terminations too tight (that also causes problems) but just good and snug...
Good luck,
Jon

Hi Spanky, I assume your watt meter is one of those things that plugs into the wall socket and you plug your appliance into it.
If that is how it is setup the voltage drop is in the house wiring or the power company. What is the total load? is it below the safe working load of the wall socket. I am guessing about 1200 watts at 120v.
If you have 2 or more power feeds(check circuit breakers) you could spread the load.

I haven't checked it at the panel, and it is a plug-in type meter. The wiring is 12-gauge and there is no warmth to the wires at all, so I think I'm probably ok. I may use a multimeter at the panel to see if there is any drop on that end.

Thanks for all of the replies.