Will a transfer switch reduce voltage loss?

Here’s how to find out without getting out your calculator or slide rule….

Hello Mike,

I have a class C with a diesel generator.  I do not have a transfer switch so I plug my shore line into a plug in the electrical bay. My shore line is 36 foot long.

My question:  Will installing an automatic transfer switch prevent voltage loss from my generator by eliminating the 36 foot short line?  And if I do this can this also reduce heat?

Thank you, David M

Hey David,

Here’s how to calculate the voltage loss on 36 ft of 10 gauge power cord at 30 amperes of current. You can find this easy online voltage drop calculator HERE.

Let’s enter your numbers…

Here’s the results…

As you can see, the most voltage drop you might save would be around 2.24 volts. And probably a little less since there could be some voltage drop in the Automatic Transfer Switch you propose to install. Perhaps not enough to worry about unless you’re right on the edge of not having enough voltage at the pedestal.

Also, if you have a 2.24 volt drop at 30 amps, that ends up creating around 67 watts of heat at maximum current. Not much heat when it’s spread out over 36 ft of shore power cord. So it’s up to you to decide if adding an ATS is worth getting back the extra 2 volts when you’re at maximum amperage draw.

Let’s play safe out there… Mike