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Weird things going on

531 Views 29 Replies 9 Participants Last post by  hornetd
Back story... when i bought my home (1956 model) 5 years ago. the foyer light and the doorbell worked fine.

Now... so i replaced the foyer light fixture with an LED fixture and now the light doesnt turn of completely. It dims down a little bit but it still is on.(swapped 3 diff fixtures with same results. Swapped light switch too)

Now to the doorbell. When the light is off/dim and you ring the bell, the light turns fully on and the bell rings. But if the light is on the bell doesn't work. I have replaced the doorbell transformer thinking it could be bad and back feeding to the light. No change.
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I have an LED can light in my bath rm that does the same thing. I've been told that it's caused by a neutral and hot being swapped somewhere along the line. I think I checked all the devices on the circuit but the LED still glows when off.
 

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Now to the doorbell. When the light is off/dim and you ring the bell, the light turns fully on and the bell rings. But if the light is on the bell doesn't work. I have replaced the doorbell transformer thinking it could be bad and back feeding to the light. No change.
Sounds like the door bell has somehow gotten mixed into the switch loop instead of direct powered.
Do you know where the doorbell transformer is?
Tell us about all the wires in the old fixture box. Did you make any changes other then remove the two wire from the old fixture and connect to the new fixture?
 

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I have only seen dimmed LED bulbs with dimmer switches, myself, where we changed light fixtures in the dining room and the new LED dimmers ( from Home Depot, went through three different models ) would not actually turn the light off. They only dimmed to a certain level, and if your power draw was below that, lights remained dimly lit.
 

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Try this... Turn the switch off on the problem light and with the switch off have someone watch it and turn off the breaker for that circuit. If the Led goes out then turn the breaker back on. Do the same with the other breakers and see if shutting one of the other breaker turns off the LED.

Not sure what they will tell you but it could be some NCV (non contact voltage) that is keeping the light on... Just a guess.

If none of that works try changing the switch or better yet get a different brand of LED
 

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Discussion Starter · #14 ·
My advice is first buy a voltage tester or multitester. I do not mean a non-contact tester.
Have one.
Try this... Turn the switch off on the problem light and with the switch off have someone watch it and turn off the breaker for that circuit. If the Led goes out then turn the breaker back on. Do the same with the other breakers and see if shutting one of the other breaker turns off the LED.

Not sure what they will tell you but it could be some NCV (non contact voltage) that is keeping the light on... Just a guess.

If none of that works try changing the switch or better yet get a different brand of LED
Back story... when i bought my home (1956 model) 5 years ago. the foyer light and the doorbell worked fine.

Now... so i replaced the foyer light fixture with an LED fixture and now the light doesnt turn of completely. It dims down a little bit but it still is on.(swapped 3 diff fixtures with same results. Swapped light switch too)

Now to the doorbell. When the light is off/dim and you ring the bell, the light turns fully on and the bell rings. But if the light is on the bell doesn't work. I have replaced the doorbell transformer thinking it could be bad and back feeding to the light. No change.
So a little more info is for you. Yes i have a voltage tester. A fluke 87.
1. These are flat panel led fixtures. No bulbs.
2. When i put the original fixture back with an old incandescent bulb it did not light up but there was a low amount of voltage to the receptacle. Around 18 volts
3. None of the other 3 lights and 2 ceiling fans on this circuit have any problems.
4. I did try turning all the other breakers off to check if another circuit was the issue... no.
 

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Discussion Starter · #16 ·
Sounds like the door bell has somehow gotten mixed into the switch loop instead of direct powered.
Do you know where the doorbell transformer is?
Tell us about all the wires in the old fixture box. Did you make any changes other then remove the two wire from the old fixture and connect to the new fixture?
Transformer is on the attic and has been replaced and i made no changes to the wires in the box. Connected directly to the black and white wires in the box
 

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Let's go to the transformer issue. With your fluke tester, what is the voltage to the transformer with the center switch both off and then on.
Before I try to describe what I'm guessing is going on I need to define a couple of things

A wire is a single conductor made of copper, if God loves you, or aluminum, if you really irritated God at one time or another, that is covered with some insulating material so as to keep it from connecting to another conductor in the same cable, conduit, or other wiring pathway.

A Cable is an assembly of wires with an overall covering to protect the insulation on the individual conductors from being worn down or damaged. Cables, in nearly all household uses, have 2 or more wires in them. The exceptions don't apply to this situation so don't worry about them right now.

Because the Equipment Grounding Conductor of this circuit might be in the form of a wire or in the form of a cable jacket I'm going to ignore all of the EGCs except to say that no matter what you need to do to accomplish it all the EGC must be connected to each other, the strap of the switch, and the green, or green with one or more yellow stripes, lead of the luminaire. If you canot find the means to do that then take and post photographs of each box with the luminaire and the switch out of the way.

I think that dcwired has this nailed. I suspect that your transformer has ended up in parallel with the switch.

The doorbell is powered by the current induced into the secondary winding by the magnetic field of the current in the primary winding.The primary winding of the doorbell transformer is wound for 120 volts. The secondary produces the voltage and current needed to operate the doorbell. All we need to be concerned with here is the primary winding so ignore the role of the secondary winding unless I specifically mention it.

When the light switch is open, or turned off if you prefer, the doorbell transformer's primary winding is in series with the light. Since the transformer has the highest impedance the secondary winding is producing enough current to power the doorbell when the light switch is off. Even though the switch is off enough current bypasses the switch through the transformer primary to cause the LED luminaire to glow dully. That is why the open switch does not completely shut off the luminaire.
Font Rectangle Parallel Number Drawing


I'm sorry I don't have the computer skills to draw this. Since the switch is in parallel with the doorbell transformer primary when it is turned on; which is called closed by electricians; the doorbell transformer's primary is shunted out. That means it is bypassed, or shorted out if you prefer, because the switch is a very low impedance pathway it conducts the current past the transformer without the current having to go through the transformer winding. Without the transformer winding in the circuit, because the closed switch bypasses it, all of the voltage available is across the LED luminaire's load. That causes enough current to flow through the luminaire to fully light it.

So what happened. Forgive me but I can only guess. It depends on whether the transformer is at the lighting outlet box in the ceiling or at the switch box that controls that lighting outlet. I'm going to guess the transformer is at the lighting outlet box sort off like this.
Bicycle part Electrical wiring Gas Nickel Wire

It's not important how the wires get to the lighting outlet box. It only matters how they are connected to the 2 loads that are located in that box. One of those loads is the transformer's primary winding. The other load is the LED luminaire.

There are 2 basic ways to switch lights. One is to switch the supply. The other is to bring the always on energized conductor; the hot if you will; of the supply down to a switch and then the switched on and off wire back to the light. That is called a switched leg. Here is how you tell them apart.

If it is switched supply there will be 2 or more cables with each one connected to a knockout of the switch box and one black wire from each cable connected to the switch. There would also be a splice in the switch box to allow the Grounded Current Carrying Conductor, that most of us call the neutral, to continue on to the lighting outlet box in the ceiling.

If it is a switch leg there will only be one 2 wire cable connected to the switch box. If the installer followed good practice then the white wire of that cable is spiced to the energized conductor in the lighting outlet box and has become part of that always on energized conductor. Recent additions of the US NEC require that the white wire of the switch leg be coded with some marking other than white or green but that may not have been done in this case depending on the code edition in effect at the time the work was done. That white wire will be terminated to one of the terminals of the switch. The black wire of the cable down to the switch box will be connected to the black wire lead of the luminaire and the end in the switch box will be terminated to the other terminal of the switch. When the switch is closed, or turned on if you prefer, the current flows from the black energized conductor of the supply cable in the lighting outlet box, into the white wire of the cable down to the switch box, through the switch, and then through the black wire from the switch box back up through the cable from the lighting outlet box, through the luminaires black wire lead, through the load inside the luminaire, out of the white lead of the luminaire, through the white "neutral" wire of the branch circuit, and back to were the branch circuit cable came from. I suspect that a switched leg is what you have and what follows will be based on the luminaire being controlled by a switch leg.

If the circuit were functioning normally 1 of the 2 jumpers from the transformer primary, which may not be color coded at all, will be one of the 3 wires spliced to the black wire of the branch circuit supply cable; that comes into the lighting outlet box; and also to the white wire of the cable to the switch box. The other jumper from the transformer will be one of 3 wires spliced to the white wire of the branch circuit supply cable and the white lead wire of the luminaire. Neither transformer jumper would be spliced to the black wire from the switch box and the black lead wire of the luminaire.

If I have guessed correctly and the transformer is located at the ceiling lighting outlet box, I think you will find that one of the jumpers from the doorbell transformer is spliced to the black lead from the luminaire and the black wire from the switch cable. If you move that one jumper to the splice, which has no luminaire lead spiced with it's other wires, which includes the black wire of the branch circuit cable and the white wire of the cable to the switch, then everything should resume working normally.

You will end up with one of the transformer jumpers spliced to the white wire of the branch circuit supply cable together with the white lead wire of the luminaire and the other jumper from the transformer spliced to the black wire of the branch circuit supply cable and the white wire of the cable to the switch. Once you do that the transformer and the luminaire will share the current flowing in the branch circuit supply cable wires. The transformer will always be energized, thus ready to power the doorbell, and the LED luminaire will be switched fully on or fully off.

I really enjoy knowing when my suggestions work. I'm vain enough to find that rather gratifying. I may have worded this too complexly to follow. I may also have guessed wrong about which box the transformer is attached to. If I did guess wrong about were the transformer is located STOP and tell us that. Then one of us can describe how to rewire it so that it will work. That person might also have the computer drawing skills, which I lack, to make clear color coded drawings of the proper way to connect the wires.

Tom Horne
 

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Discussion Starter · #20 ·
Before I try to describe what I'm guessing is going on I need to define a couple of things

A wire is a single conductor made of copper, if God loves you, or aluminum, if you really irritated God at one time or another, that is covered with some insulating material so as to keep it from connecting to another conductor in the same cable, conduit, or other wiring pathway.

A Cable is an assembly of wires with an overall covering to protect the insulation on the individual conductors from being worn down or damaged. Cables, in nearly all household uses, have 2 or more wires in them. The exceptions don't apply to this situation so don't worry about them right now.

Because the Equipment Grounding Conductor of this circuit might be in the form of a wire or in the form of a cable jacket I'm going to ignore all of the EGCs except to say that no matter what you need to do to accomplish it all the EGC must be connected to each other, the strap of the switch, and the green, or green with one or more yellow stripes, lead of the luminaire. If you canot find the means to do that then take and post photographs of each box with the luminaire and the switch out of the way.

I think that dcwired has this nailed. I suspect that your transformer has ended up in parallel with the switch.

The doorbell is powered by the current induced into the secondary winding by the magnetic field of the current in the primary winding.The primary winding of the doorbell transformer is wound for 120 volts. The secondary produces the voltage and current needed to operate the doorbell. All we need to be concerned with here is the primary winding so ignore the role of the secondary winding unless I specifically mention it.

When the light switch is open, or turned off if you prefer, the doorbell transformer's primary winding is in series with the light. Since the transformer has the highest impedance the secondary winding is producing enough current to power the doorbell when the light switch is off. Even though the switch is off enough current bypasses the switch through the transformer primary to cause the LED luminaire to glow dully. That is why the open switch does not completely shut off the luminaire.
View attachment 728098

I'm sorry I don't have the computer skills to draw this. Since the switch is in parallel with the doorbell transformer primary when it is turned on; which is called closed by electricians; the doorbell transformer's primary is shunted out. That means it is bypassed, or shorted out if you prefer, because the switch is a very low impedance pathway it conducts the current past the transformer without the current having to go through the transformer winding. Without the transformer winding in the circuit, because the closed switch bypasses it, all of the voltage available is across the LED luminaire's load. That causes enough current to flow through the luminaire to fully light it.

So what happened. Forgive me but I can only guess. It depends on whether the transformer is at the lighting outlet box in the ceiling or at the switch box that controls that lighting outlet. I'm going to guess the transformer is at the lighting outlet box sort off like this.
View attachment 728102
It's not important how the wires get to the lighting outlet box. It only matters how they are connected to the 2 loads that are located in that box. One of those loads is the transformer's primary winding. The other load is the LED luminaire.

There are 2 basic ways to switch lights. One is to switch the supply. The other is to bring the always on energized conductor; the hot if you will; of the supply down to a switch and then the switched on and off wire back to the light. That is called a switched leg. Here is how you tell them apart.

If it is switched supply there will be 2 or more cables with each one connected to a knockout of the switch box and one black wire from each cable connected to the switch. There would also be a splice in the switch box to allow the Grounded Current Carrying Conductor, that most of us call the neutral, to continue on to the lighting outlet box in the ceiling.

If it is a switch leg there will only be one 2 wire cable connected to the switch box. If the installer followed good practice then the white wire of that cable is spiced to the energized conductor in the lighting outlet box and has become part of that always on energized conductor. Recent additions of the US NEC require that the white wire of the switch leg be coded with some marking other than white or green but that may not have been done in this case depending on the code edition in effect at the time the work was done. That white wire will be terminated to one of the terminals of the switch. The black wire of the cable down to the switch box will be connected to the black wire lead of the luminaire and the end in the switch box will be terminated to the other terminal of the switch. When the switch is closed, or turned on if you prefer, the current flows from the black energized conductor of the supply cable in the lighting outlet box, into the white wire of the cable down to the switch box, through the switch, and then through the black wire from the switch box back up through the cable from the lighting outlet box, through the luminaires black wire lead, through the load inside the luminaire, out of the white lead of the luminaire, through the white "neutral" wire of the branch circuit, and back to were the branch circuit cable came from. I suspect that a switched leg is what you have and what follows will be based on the luminaire being controlled by a switch leg.

If the circuit were functioning normally 1 of the 2 jumpers from the transformer primary, which may not be color coded at all, will be one of the 3 wires spliced to the black wire of the branch circuit supply cable; that comes into the lighting outlet box; and also to the white wire of the cable to the switch box. The other jumper from the transformer will be one of 3 wires spliced to the white wire of the branch circuit supply cable and the white lead wire of the luminaire. Neither transformer jumper would be spliced to the black wire from the switch box and the black lead wire of the luminaire.

If I have guessed correctly and the transformer is located at the ceiling lighting outlet box, I think you will find that one of the jumpers from the doorbell transformer is spliced to the black lead from the luminaire and the black wire from the switch cable. If you move that one jumper to the splice, which has no luminaire lead spiced with it's other wires, which includes the black wire of the branch circuit cable and the white wire of the cable to the switch, then everything should resume working normally.

You will end up with one of the transformer jumpers spliced to the white wire of the branch circuit supply cable together with the white lead wire of the luminaire and the other jumper from the transformer spliced to the black wire of the branch circuit supply cable and the white wire of the cable to the switch. Once you do that the transformer and the luminaire will share the current flowing in the branch circuit supply cable wires. The transformer will always be energized, thus ready to power the doorbell, and the LED luminaire will be switched fully on or fully off.

I really enjoy knowing when my suggestions work. I'm vain enough to find that rather gratifying. I may have worded this too complexly to follow. I may also have guessed wrong about which box the transformer is attached to. If I did guess wrong about were the transformer is located STOP and tell us that. Then one of us can describe how to rewire it so that it will work. That person might also have the computer drawing skills, which I lack, to make clear color coded drawings of the proper way to connect the wires.

Tom Horne
Tom, thank you for the time you took to reply. I think i understand what you're trying to tell me. Since this house was built in 1956 it is all 2 wire copper cable. The circuit is a single cable supplying 5 boxes. The doorbell transformer isn't attached to a box. It was simply screwed to a ceiling joist. From what i could see when i was up there, it is spliced into the cable just before the box with my problem light. It is heavily wrapped in old cloth tape. I'll go back up tomorrow and try to get a better look. And maybe a picture or 2. Again thank you and every one else for all the help.
 
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