So we bought a new home in July. Shortly after moving in, I noticed a few peculiarities in the electricals of the house: a string of electrical outlets downstairs had no ground. Two circuits on the panel could not be enabled simultaneously and after installing a 3-way capable dimmer in a 3-way lighting circuit, I could only turn it on and off from one side, not both.
Issue the first – no ground: a friend of mine is an aspiring electrician and has been studying and will soon take courses. He came over for an hour or so when he was in the area and tackled this first issue. What we discovered is that whoever wired the outlets neglected to attach the ground from the panel to the box or the outlet, and in addition, the unattached ground cable was coming in contact with the neutral contact on the socket. Bad mojo. Fixed this situation and all the outlets on that string now function perfectly.
Issue the second – mutually exclusive circuits: the same friend pondered over this for a bit and after having checked the house for outlets or lights that were not functioning when both breakers were off and coming up empty handed, we inferred that they were unused circuits and someone had foolishly tied them together in a junction box somewhere. We left it at that for the time being with both breakers off. My dad came to visit not long ago and I mentioned this issue to him and he said it sounded as if they might be going to a split outlet that didn’t have the split tab removed. So we searched again and found nothing when I decided to check behind a dresser that came with the house – voila – an outlet with no power. I opened up the cover and sure enough, there were two separate ‘hot’ leads coming attached to the top and bottom socket, and the the split tab was still present. I wiggled it off with my pliers and as you might guess, both circuits could now be activated at the same time and the outlet works.
Issue the third – 3-way dimmer: The same friend pondered this one as well but not being well versed with 3-way circuits yet, he vowed to research it and get back to me. In the meanwhile, I found myself with a few spare hours one evening. So I looked up proper functioning of a 3-way circuit complete with diagrams. I removed both switches from the circuit and probed for current. I identified the incoming ‘hot’ lead and connected that to the odd coloured terminal of the 3-way dimmer, thus identifying the other two leads as the ‘travellers’ which I connected to the like-coloured terminals of the dimmer. From there I was able to determine which two wires were the travellers at the other switch location and connected those to the like-colored terminals of the standard 3-way switch leaving the lead to the lights to be connected to the odd coloured terminal of the standard switch. I powered the circuit back on and everything works as expected. Sometimes it helps to just start from scratch.
My hope is that if anyone else is struggling with strange power situations they might stumble upon this entry in their searching and it might be of help.
Of course, the usual warnings and caveats apply: this is for educational purposes only, I am not a professional (nor is my budding electrician friend yet), you attempt anything described here at your own risk, always turn off a circuit at the breaker and confirm it is off at the location before attempting any work.
Good luck!