What's a Line Splitter?

It's a handy gadget for measuring AC current in an extension cord...

Hey Mike,

Are you familiar with this device or ever used one before? I have not. It looks like a good idea.

Hey Dave,

Yes, I’ve used this type of device many times. It’s called a line splitter and it allows you to use a clamp ammeter to measure current flow in an extension cord. As you show in your picture, it plugs into an outlet and you clamp the ammeter through one of the loops.

The X1 loop measures the actual amperage going through the extension cord. While the X10 loop multiplies the measurement by a factor of 10. So an actual 1 ampere of current in the power cord will measure 10 amperes on your clamp meter. This make measurements more accurate for small currents, so 10mA of current in the power cord will measure 100mA on the meter if you clamp your ammeter through the 10X loop.

This particular line splitter from Harbor Freight also has meter lead connections marked N, E and L which stand for Neutral, Earth (Ground) and Line. That’s really handy for measuring the voltage as well as amperage on an extension cord.

Watch this video on why you need to split the lines to measure amperage

Here’s the best Line Splitter I’ve ever seen, but it’s no longer made. Sorry…

I also have a pair of these HT Line Splitters which are unique with a separate test loop for measuring leakage current on the ground wire of your RV.

This HT Line Splitter has 15-amp pigtail connectors, so you just need to add appropriate adapters for your 30- or 50-amp shore power plug to test leakage current. Combined with a low-current clamp meter, this splitter allows you to find ground fault currents as low as 1 mA. That’s perfect for troubleshooting GFCI nuisance tripping my an RV. It’s no longer made, but if you find one somewhere for sale, grab it!

I’ll do a video soon showing a few tricks with Line Splitters.

Let’s play safe out there… Mike