two black wires in light fixture box


Old 01-08-00, 01:02 PM
Visiting Guest
Posts: n/a

HELP! I am trying to replace an old flourescent fixture with a new incandescent fixture. When I took off the old fixture, I found only two black wires and no white wire or ground wire. My husband and I tested the new fixture by hooking the white and black wires on the new fixture to the two black wires, first one way and then the other. It worked both ways. Is this safe? Can we just hook this up any way we like? What about the missing ground wire? BTW: Our house is about 50 years old, and this may be the original wiring.
TW in KS
Old 01-08-00, 02:24 PM
Visiting Guest
Posts: n/a

Grounding first:
In your case there is nothing you can do. This is a direct hookup and since your entire system is not a grounded system, putting a grounding wire pigtail from fixture to box is superfluous.
For a flourescent fixture the old wiring didn't really matter.
However, for an incandescent, as far as working it doesn't matter either but this is what is happening.
In your case it is possible for the lamp shell to be "hot" rather than the little patella on the bottom of the shell.
To check which is hot, do the following.
Leave the fixture the way you have it and remove lamp, knowing it is in the on position. Then take a tester and with one prong on either the shell (white) screw shell and the other prong on something you know is grounded (you may need a longer single strand wire to this as well as another person) If you get a reading of 110 volts you need to switch the wires. You can leave them but fair warning you don't want to touch the shell when removing lamp. Sometimes they stick above the outside covering and you could get shocked if you are grounded.
(Just for your information, there is a tester available that can check this without the scenerio described above, but chances are you don't have it.
Old 01-09-00, 01:26 AM
Visiting Guest
Posts: n/a

hi ,twheeler17
sounds 2 me like what u have is the old knob and tube wireing. do as david said and u will find the hot. the tester he is talking abought is an induction tester u can buy 1 at walmart 4 around 10 bucks, and there easy 2 use, and i believe that instructions r included. just a safty note u may want to have a electrician check out your wireing to be sure that is still intact and safe if its knob and tube, as i have seen old knob and tube wireing with bare spots in it.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: