I recently spent several frustrating hours trying to figure out why an outlet on a new branch circuit would not power a load even though there was proper polarity at the outlet, my non-contact voltage tester showed a live circuit, and my multi-meter showed 110 volts both in the outlet slots and at the side-wire screws. I tested all conductors for continuity, remade all connections, tried four other duplex outlets and three other breakers, and even replaced some of the wiring. Nothing worked. Finally, I hooked up the hot side to another breaker in a different "slot" in the breaker box. That powered the load in the outlet, so I then hooked up the hot side of the circuit to the original breaker and put it in that same slot and it worked. I concluded that something is wrong with the buss bar at the position where the breaker I'd been using was installed. After finishing the job and putting the cover back on the box, I labeled that slot as not working and indicated that the breaker itself may be OK. The box and breakers are Cutler Hammer.
I found no visual evidence of a problem with the buss bar. Is this problem common? Why would my meter have shown 110 volts at the outlet when the outlet wasn't able to power a load? I had thought at first that the outlet was haunted but was happy to find that there was a "real" reason for the problem.
Does anyone have a step-by-step checklist of things to try when troubleshooting a non-working outlet (or any other problem for that matter)? I'm envisioning something that would start with the most likely causes and solutions and work down to the more exotic ones. Such a checklist sure would have saved me time.
Best Answer
Some breaker panels have blank slots at the end, which could mechanically accept a breaker, but their tabs are not live, if they have tabs at all. This is done to lower manufacturing costs and reuse one chassis with different bus bar assemblies.
It could also be a piece of tape, clear insulation, or severe corrosion over that spot on the bus bar. Depending on the resistance, it may let a charge large enough to measure get through, but when an real load is placed on it, the resistance is too high for it to run.