Making bad connection

jburd964

why am i getting 110 volt when checking one side, black, of leg? There are multiple plugs and some being GFI's on the same leg. I've opened all receptacles that I can locate on the leg and checked that no wires were reversed, they were all ok. How can this happen?

secutanudu

Can you provide some more details one exactly what test is giving you 110 volts?

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Andrew

jburd964

I was checking wires to see if what was being feed threw want. When I was checking to see which way the feed came in i contacted both blacks and it read 110 volts. There are other plugs including gfi's past this plug

Yoyizit

In case one of these is in series with a load, run a large incand. lamp to a known good ground from each black wire and measure the volts across the lamp each time.
This method will trip any working upstream GFCIs.

jburd964

Will give it a try tomorrow. Thanks. By chance if something is plugged into one of the up stream plugs, how would that effect the voltage reading of down steam outlet in series across hot side?

Yoyizit

A resi. outlet "looks like" ~120v in series with ~0.3 ohm. A 10 A load will drop the voltage at a particular outlet and outlets downstream of it by ~3v, e.g., from 120v to 117v or 110v to 107v.

"The Thévenin equivalent can be used as a good model for a power supply or battery (with the resistor representing the internal impedance and the source representing the electromotive force). The circuit consists of an ideal voltage source in series with an ideal resistor."
so the entire PoCo - from an outlet - all the way back to the generators and turbines - can be represented by 120v in series with 0.3 ohm.

At your load center it's 240v in series with slightly more than 0.02 ohms.

A car battery? 12.8 v in series with about 0.02 ohms but the 0.02 depends on the current draw and several other things.