HELP: Existing Switch Loop
#1
01-05-18, 07:44 AM
HELP: Existing Switch Loop
I am attempting to install a replacement light fixture in our utility room and it appears the existing box is wired into a switch loop. A little summary:
Now I have tried a few combinations that seem to fail in one way or another.
I would greatly appreciate any help I can receive on this and will post any other info that is needed. Thank you all.
- The original light fixture was one bulb, I am replacing with a two bulb fixture
- There is one red and four wire bundles (black, white, and ground) coming in to the box (see attached image)
- One bundle is directly from the switch
- One bundle is directly from the power source
- Two bundles go to other lights, outlets, and smoke detectors
- Switch is wired with BLACK on top and WHITE on bottom
Now I have tried a few combinations that seem to fail in one way or another.
- (Switch White to Black Source) + (Switch Black to Light Black) + (Light White to White source and outgoing white)
- No light
- (Switch White to Black Source) + (Switch Black to Light White) + (Light Black to ALL white)
- No light
- (All White to Light White) + (Switch Black to ALL Black)
- Light but no effect by switch (duh!)
I would greatly appreciate any help I can receive on this and will post any other info that is needed. Thank you all.
Last edited by brandonp; 01-05-18 at 07:47 AM. Reason: Image too small
#2
01-05-18, 09:36 AM
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I don't know what the red wire is for. Pictures or a more detailed description is needed.
Your above quote should work, the description is correct.
Source hot (black) goes to switch white (loop) and down stream lights and receptacles.
Source neutral goes directly to the light and down stream lights and receptacles.
Black from switch goes to the light black(s) only and does not connect to anything else.
Red to be determined.
(Switch White to Black Source) + (Switch Black to Light Black) + (Light White to White source and outgoing white)
No light
No light
Source hot (black) goes to switch white (loop) and down stream lights and receptacles.
Source neutral goes directly to the light and down stream lights and receptacles.
Black from switch goes to the light black(s) only and does not connect to anything else.
Red to be determined.
#3
01-05-18, 09:38 AM
Group Moderator
Did you open all the wiring connections in the box ??
The red could possibly be from the smoke detector circuit.
DO NOT randomly connect that wire.
The red could possibly be from the smoke detector circuit.
DO NOT randomly connect that wire.
#4
01-05-18, 09:51 AM
Don't take offense, but are you sure you have two good light bulbs in your fixture? I was pulling my hair out after installing a couple outdoor fixtures because they weren't working, and the issue turned out being I was unknowingly using 12Vdc bulbs. They kept burning out as soon as I flipped the switch, but didn't realize what was going on because I couldn't see the bulbs burning out (because the switch is inside and fixtures are outside out of view) 
Does the outlet have power?
Could be a bad switch. I have encountered that before. You can temporarily short the white and black inside the switch box to bypass it (e.g. use a spare piece of insulated wire to short the two screws).
Does the outlet have power?
Could be a bad switch. I have encountered that before. You can temporarily short the white and black inside the switch box to bypass it (e.g. use a spare piece of insulated wire to short the two screws).
#5
01-05-18, 02:08 PM
Originally Posted by Handyone
I don't know what the red wire is for. Pictures or a more detailed description is needed.
Your above quote should work, the description is correct.
Source hot (black) goes to switch white (loop) and down stream lights and receptacles.
Source neutral goes directly to the light and down stream lights and receptacles.
Black from switch goes to the light black(s) only and does not connect to anything else.
Red to be determined.
Your above quote should work, the description is correct.
Source hot (black) goes to switch white (loop) and down stream lights and receptacles.
Source neutral goes directly to the light and down stream lights and receptacles.
Black from switch goes to the light black(s) only and does not connect to anything else.
Red to be determined.
- BLACK SOURCE :: SWITCH WHITE + OUTGOING BLACK
- SOURCE WHITE :: LIGHT WHITE + OUTGOING WHITE
- SWITCH BLACK :: LIGHT BLACK
#6
01-05-18, 02:12 PM
Originally Posted by mossman
Don't take offense, but are you sure you have two good light bulbs in your fixture? I was pulling my hair out after installing a couple outdoor fixtures because they weren't working, and the issue turned out being I was unknowingly using 12Vdc bulbs. They kept burning out as soon as I flipped the switch, but didn't realize what was going on because I couldn't see the bulbs burning out (because the switch is inside and fixtures are outside out of view)
Does the outlet have power?
Could be a bad switch. I have encountered that before. You can temporarily short the white and black inside the switch box to bypass it (e.g. use a spare piece of insulated wire to short the two screws).
Does the outlet have power?
Could be a bad switch. I have encountered that before. You can temporarily short the white and black inside the switch box to bypass it (e.g. use a spare piece of insulated wire to short the two screws).
Originally Posted by PJmax
Did you open all the wiring connections in the box ??
The red could possibly be from the smoke detector circuit.
DO NOT randomly connect that wire.
The red could possibly be from the smoke detector circuit.
DO NOT randomly connect that wire.
#7
01-06-18, 10:56 AM
Thanks
Thank you all, I picked up a brand new switch and re-wired as I had before and everything works fine now. An added bonus, my wife is done saying "I told you so" 
#8
01-06-18, 01:34 PM
Group Moderator
Oh no...... you aren't the type that puts old switches in the electrical bin for future spares. 
