Electrical – measuring low voltage when I connect this fluorescent fixture to an existing circuit

electricalswitchwiring

My bathroom has two switches: one [was] connected to two overhead can lights (with CFLs), and one [was] connected to a fluorescent wall sconce (one of those ugly circular plastic things that I can't seem to find on Google). To make room for a ceiling fan in the switch bay and since there is no need for two switches for three lights, I created a single circuit to run all the lights.

Trouble is, the lights won't turn on. The voltage across the circuit is measuring something like 24V. When I bypass the fluorescent sconce, the overhead lights work and the voltage across the circuit measures an appropriate 115V (good enough).

Can wall fluorescents (there are two external ballasts within the sconce; it takes two of these bulbs) be wired into a main overhead circuit? I see in this related question that there's something about them needing to be wired in parallel, rather than in series, but the response is a little hazy to me. If they need to wired in parallel, can they be run on the same circuit? I'd also be happy to replace this ugly little sconce.

Best Answer

Simple answer to your question is: All load fixtures must be wired in parallel, never in series. This means you need to feed each fixture with 120vac. You can use a single run of wire, but the feed to the next fixture must be wired so that the hot and neutral are always connected uninterrupted to each fixture. Practically speaking, the black hot wire coming from the switch must be connected to the black wire going to the next fixture as well as the black wire for the local fixture in the same wirenut. Same goes for the neutral and ground conductors. This is parallel wiring. If you still have a low voltage reading, then you have a defective ballast or an open neutral.