110 outlets don't work even when showing hot on the multimeter

[jschanafelt]

Explane this please. Just installed a shore power 50 AMP terminal at our temporary job site while we build a new home. Took a bit but got it done. Metered the power cord and everything is good to the trailer. Inside, 120 volt works for the A/C's. All outlets show to be hot, but do not work. All GFIs checked. The wall outlets in and out do not work at all. The refer will not work on A/C but works on gas. Microwave works. Breakers are set. Fuses show good though I have not pulled each one yet.
Help!! Wife demands her morning coffee. It could be a rough six months fi I don't get fixed.
Thank you in advance.

 

[wdk450]

Do you have both 50 amp phases present on the breaker panel?

Start at the panel feed wires to the outlets after checking both incoming phases on the mains breakers.

Outlets known to have flaky Insulation displacement connectors (like Scotchlok v's) instead of screw terminal outlets like in houses. Daisy chaining these IDC's just makes connections worse.

Having an AC voltage sniffer (non contacgt AXC detector) makes this troubleshooting easier. I found a DVM with this function included.

 

[david-steph2018]

Check the outlets with a meter and make sure they are hot. Most of the outlets in the RV are controlled by 1 GFCI, usually located around a water source, like the bathroom. As in our Road Warrior.
If the GFCI will not reset, it does not have power, check the breakers again. Do not just look at the breaker, reset it, sometimes it is hard to see if the breaker has tripped or not.
Did the outlets work the last time you used the rig? Make sure everything else on the same leg as the outlets work, could the new terminal be wired incorrectly?

 

[taskswap]

Can you give more information on what "metered the power cord and everything is good" means? Lots of wiring issues are related more to bad grounds and neutrals than bad hots. Some can be dangerous.

If you don't already have one my first instinct would be to get a Power Watchdog or similar. It shows all the possible configurations of wiring and voltage-level issues and can be a lifesaver for RV wiring. It'll tell you exactly what's wrong. Otherwise it would be good if you could list exactly what you tested and how.

 

[wdk450]

One thing to remember about using the modern digital volt/ohm meters: these are pretty much all high Impedance input voltmeters, meaning they draw a miniscule amount of current from the measured circuit for the measurement (no loading of the circuit). This is a good thing for low current solid state electronics troubleshooting, but won't show poor connections for higher power circuits.

In the hospital I once worked on a ElectroConvulsiveTherapy (ECT) (i.e. "shock treatment") generator that wouldn't deliver the desired current to the patient (or test load). The patient hookup cable measured continuity with my digital voltmeter. Finally I disassembled the end connector on the cable and saw that of the twisted stranded wire used, just 1 strand was still making contact, so current couldn't be delivered although the DVM measured continuity. Re-soldering the stranded wire connection fixed the problem.

So, I am saying that you may have a poor connection that just shows voltage present with a high impedance DVM, but won't supply the needed current for the load.

 

[jschanafelt]

Wow thanks for the quick responces.
I'll need a diffiernt system for metering the voltage.
Everything workted the last time out. The coach was in the shop for new gaskets on the slides. Just got it out Friday. I know that once before, I shorted a wire with a screw mounting the roof ladder.
While installing the shore power plug, I got the neutral on the wrong bus in the breaker box. Fixed that ant the A/C's both lit up. ??? Ground is on the same bus.
"digital volt/ohm meters" was used. ??? Every time I tested an outlet, I got 125 V measuring both the neutral and ground to the hot leg.
Thank you guys.
John Schanafelt
2015 Sundance 3280 RES

 

[wdk450]

Neutral and ground should be SEPERATE buses, only connected together at one point in the park supply system.

 

[gasman]

Check the pedestal connections. The 50 amp circuit is a 240 volt circuit not 120 volts. Many times you will find that it is wired incorrectly.

 

[wdk450]

Check the pedestal connections. The 50 amp circuit is a 240 volt circuit not 120 volts. Many times you will find that it is wired incorrectly.

The 50 amp circuit is 2 120 volt AC circuits 180 degrees out of phase with each other. 120 volts to neutral (and ground) on each phase, 240 volts phase 1 hot to phase 2 hot. Our Heartland RV's use the 2 120 volt phases separately; Only very expensive motorcoach RV's use the full 240 volts potential for special high-end appliances.

See pages 5-6 of this Heartland library document: https://manuals.heartlandowners.org/manuals/User Guides/Electrical V2.pdf

 

[Hollandt]

Wow thanks for the quick responces.
I'll need a diffiernt system for metering the voltage.
Everything workted the last time out. The coach was in the shop for new gaskets on the slides. Just got it out Friday. I know that once before, I shorted a wire with a screw mounting the roof ladder.
While installing the shore power plug, I got the neutral on the wrong bus in the breaker box. Fixed that ant the A/C's both lit up. ??? Ground is on the same bus.
"digital volt/ohm meters" was used. ??? Every time I tested an outlet, I got 125 V measuring both the neutral and ground to the hot leg.
Thank you guys.
John Schanafelt
2015 Sundance 3280 RES

there should be two hot legs on the 50 amp connection. Please see the attached. lots of good info there.

https://campaddict.com/reviews/electrical/best-rv-surge-protector/