About Bruce Grant Expertise I can answer any questions about residential electrical wiring and most questions about commercial wiring. In my own business, I insist on using best practices in all work we do (which to me means "to Code" or BETTER, using the most recommended ways to do things).
Experience I'm 65, but learned wiring basics as a teenager. I only used this knowledge for myself, friends and family until early 2002, when economic downturns suddenly made my 30 years in IT irrelevant. Through the Internet, I bought many books on wiring and electrical code and switched careers, becoming an unlicensed electrical contractor, carpenter, and handyman. I now know, after 7 years in the industry, everything I need to get a California C-10 License except some of the Industrial wiring stuff (which I'll probably never use, but need to pass the test). The main reason I haven't yet obtained the License is lack of funds to pay for it and the required insurance. Eventually, I'll get it.
Education/Credentials * BS in Physics and Mathematics from Oregon State University, 1967
* Primarily self-taught from books written for electrical and construction pros, but also informal training from more experienced pros
Past/Present Clients homeowners and small businesses in the San Francisco Bay Area, mainly on the S.F. Peninsula
Question help please. I have a new 2 lamp ceiling light to install. it seems the wiring is in the middle of the run if i understand the correct. The existing juction box has black and white lead coming in and then a black and white lead 14/2 going out of the box. The light is also run off the wall switch. the new lamp has 2 black, 2 white leads and the grounds.
Could you please tell me how to wire it?
thanks for the help
Lee
Lee, with the existing ceiling box having a black/white pair of wires coming in one hole and another black/white pair coming in from another, there are two possible Code-correct wiring configurations as illustrated in the attached diagram I've created. Notice that, in either case, the switch always interrupts the Hot wire, NEVER the Neutral.
In Configuration #1, another light and/or receptacle would ALSO be controlled by the wall switch. If that is not the case, then you probably have Configuration #2. The easiest way to tell is simply to count the number of connections to the Black and White leads coming from the existing light fixture (where the arrows are pointing). Counting those leads, there should be 3 Black wires connected together and 3 White wires connected together if you have Configuration #1. Otherwise, you will have only 2 Blacks and 2 Whites connected as in Configuration #2.
Regardless of which configuration you have, the rule for wiring the new double light fixture is the same.
Connect the 2 black leads from the new fixture the same way that the single black lead from the old fixture was connected. The same applies to the white leads and the ground lead. Each of those two connections will now have one more wire than with the old fixture!
NOTE #1:
If the old fixture did NOT have a ground lead, then connect your new fixture's ground lead (green or bare copper) to the existing ground wires coming into the junction box AND to the existing metal mounting bracket that will hold the fixture. The bracket will usually have a green screw in it just for a ground wire; if not, it will at least have a pre-threaded hole for a ground screw.
NOTE #2:
If there are no ground wires coming into the box as part of the house's wiring (shown as bare copper wires in the diagrams), then just connect to the bracket or box grounding screw.
WARNING! Until you have tested each wire AFTER turning off the circuit at the panel box, assume each wire might be Hot (this is what a pro does) -- you might have chosen the wrong circuit breaker or fuse, or, even worse, there may be some hidden mis-wiring that connects one or more wires there to a different circuit. My diagrams only show what correct wiring should be.
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