Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 10-06-2010, 09:02 AM   #1
Newbie
 
Join Date: Oct 2010
Posts: 3
Rewards Points: 10
Default

old house ceiling light:wired to black leads only, white leads wired yogether


The wiring in our house is quite old, and not to the current code. I want to replace an old fluorescent ceiling fixture with a modern "no-ballast" one.
There are 3 cables (white, black and ground) coming into the box. The 3 white wires are all wire-nutted together; the lamp is wired between one pair of blacks and the other black wire. Ground wires are grounded (actually, only two are). One of the black leads is still live though the switch is OFF.
Should I install the new light the same way as the old (after shutting down the breaker)? Thanks a lot!

michael13 is offline   Reply With Quote
Old 10-06-2010, 01:33 PM   #2
Member
 
Join Date: Dec 2009
Location: Springfield OH
Posts: 768
Rewards Points: 500
Default

old house ceiling light:wired to black leads only, white leads wired yogether


Have you opened the box containing the switch? A single cable with black/white/ground and no other?

I am guessing that your setup is, in effect, switching the neutral. You have supply going to one wire of the fixture. The other wire of the fixture is attached to the black wire going to the switch. The white wire from the switch is joined with the other white wires at the fixture box. At least, this is my guess.

My assumption is that this would not meet code if doing it today. I have always assumed that the preference to switch the hot side is to avoid having power at the fixture when the switch is off. Furthermore, I assume that this is considered preferable so that one does not shock oneself if working at the fixture and assuming that there is not power because the switch is off.

A lot of guesses and assumptions. Hopefully, you can confirm this theory with a volt/ohm meter.

oberkc is offline   Reply With Quote
Old 10-06-2010, 02:11 PM   #3
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,965
Rewards Points: 2,026
Default

old house ceiling light:wired to black leads only, white leads wired yogether


Which black wire is live when the switch is off?

Which black wire goes to the switch?

How is the third black wire connected?

Take the black wire to the switch and connect it to the light fixture black wire.

You want to take the white wire that accompanies the black wire to the switch and connect this to the hot black wire and also the third black wire.

Connect the white wire from the new fixture to the other two white wires (all wire nutted together).

Mark both ends of the white wire attached to the switch using black tape or stain (or Magic Marker ink).

Connect all the ground wires together including that to the fixture. If the fixture doesn't have a ground wire, cut a piece of bare wire (a pigtail) to connect the cluster of other ground wires to the fixture.

Incidentally if you ignore the above and take the two wires that used to be connected to the old fixture and connect them to the new fixture then it would still work.
__________________
Forget super sized fries. The Washington Redskins could promote healthy eating with First Lady Obama by choosing a (red skinned) turnip for a mascot.

Last edited by AllanJ; 10-06-2010 at 02:16 PM.
AllanJ is offline   Reply With Quote
Old 10-07-2010, 02:21 PM   #4
Newbie
 
Join Date: Oct 2010
Posts: 3
Rewards Points: 10
Default

old house ceiling light:wired to black leads only, white leads wired yogether


Thanks, oberkc and AllanJ, for the responses. I can't digest it all now, and don't have time for the light, right now - but, thanks!
michael13 is offline   Reply With Quote
Reply

Tags
3 cables in one fixture, old wiring, white leads wire nutted, wired to black leads


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Black & White kitchen questions TraGregZ Remodeling 4 01-06-2010 11:34 AM
Neutral Wire? 4x15mph Electrical 8 11-24-2008 01:00 PM
hooking up dryer....bronx ny code SURFBUG Appliances 6 10-14-2008 09:41 PM
black to black, white to ground? klassa Electrical 4 02-10-2008 07:38 AM
Old house, new light fixture, too many wires Persephonee Electrical 3 01-15-2007 08:58 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.