Strange Voltage Drop

[BigBobsBrews]

I recently rewired my 3 prong dryer outlet to a 4 prong with the help of the HBT community. I can measure 246V across the 2 hot lines, and 123V across the neutral line & either hot. (and the dryer still works great)

I also built a power cord for my control panel, using kal's specifications (http://www.theelectricbrewery.com/control-panel-part-2?page=4).

Now come the strange part, when I plug the power cord in and measure it's output voltage I get 246V across the 2 hot, but only 73V between the neutral line & either of the hot lines.

Any thoughts as to what might be going on here?

 

[BigBobsBrews]

The power cord is ~15 ft long, so i wouldn't expect a voltage drop like this.

 

[EarthBound]

Are the other sides of the hot wires connected to anything, e.g., relays?

 

[passedpawn]

Sounds like the neutral is a poor conductor. Resistance in the neutral connector (connectors, wire, etc) will raise the voltage at the connector. Current returning on the neutral is cause a voltage drop of 123 - 76 = 47V. That's a lot. Are you running any 120V appliances off the dryer cord?

I'd check all the connections on that neutral, all the way back to the fuse box.

This is exactly why we shouldn't use the neutral as a safety ground.

 

[yjfun]

Loose connection on neutral wire or corrosion on the terminals are the most likely causes but you may want to double check that you have the neutral wire connected to the silver screw on both of the cord ends and not to the green on the 4 wire end.

Just like passedpawn said this is why a green grounded conductor is now used instead of the neutral wire. It's called the life safety wire for a reason.

 

[BigBobsBrews]

There is nothing connected to the power cord yet.

I checked all my connections all the way back to the breaker box & didn't find anything suspect.

I'm beginning to doubt the trustworthiness of my "Made in Honduras" gfci, has anyone else experienced problems like this?

 

[passedpawn]

There is nothing connected to the power cord yet.

I checked all my connections all the way back to the breaker box & didn't find anything suspect.

I'm beginning to doubt the trustworthiness of my "Made in Honduras" gfci, has anyone else experienced problems like this?

If you installed the GFCI, make sure the neutral in your house wire goes to the neutral on the GFCI and not directly to the neutral bus bar in the panel. A 240VAC GFCI has 3 inputs from the load side; all are necessary.

 

[yjfun]

After you plugged the cord in did you push the reset button on the gfci?

 

[BigBobsBrews]

After you plugged the cord in did you push the reset button on the gfci?

Yes, many times. It works great.

 

[BigBobsBrews]

If you installed the GFCI, make sure the neutral in your house wire goes to the neutral on the GFCI and not directly to the neutral bus bar in the panel. A 240VAC GFCI has 3 inputs from the load side; all are necessary.

This is an In-Line GFCI, the neutral is running through it.

 

[BigBobsBrews]

After alot of frustration & troubleshooting I decided to do away with this POS in-line gfci.

I'm just going to install a GFCI breaker in my panel and use a standard dryer cord.

I just wanna double check, the white pigtail off the breaker is the neutral input, yes?

 

[BigBobsBrews]

Also this is a 30A line, with a 30A breaker in my house breaker box.

I plan to use a 50A GFCI breaker in my control panel for GFCI protection & leave the 30A breaker in the house breaker box for overcurrent protection.

Sound Good?

 

[passedpawn]

I just wanna double check, the white pigtail off the breaker is the neutral input, yes?

Probably. White is usually neutral.

 

[BigBobsBrews]

Hows this look?

 

[EarthBound]

I just wanna double check, the white pigtail off the breaker is the neutral input, yes?

It should say so on the breaker itself.

 

[BigBobsBrews]

It should say so on the breaker itself.

It's labeled "Panel"

 

[P-J]

BigBobsBrews,

Your diagram is spot on.

P-J

 

[yjfun]

Response deleted due to stupidity from lack of coffee and sleep.