Question for elec techs

RJsfishin wrote:
The little I know about this, I would say that this post explains it all. My guess was that this low voltage bulb (1.8 watt) was using the humid air as a return path to the panel. There just was no other path, period.
Why did I do it ??
I felt it was safer,.....because of the special switch that was being used in a position where the wire could get damaged. I felt the black wire has no chance of getting damaged, where as the white wire could. And shorting the white wire would do nothing more than turn the lite on. Damage to the black wire would cause a direct short.
But never fear, I redid the whole thing, and its good now
But I do know now that a low voltage led bulb will burn w/o a neutral or ground connected.

The switch is a n/o push button mounted in a box, that is mounted on the end of the door track.. When the big garage door is open, it bumps the push button switch to turn the light on to let me know if the door was left open,....see it from the house.

Sam Spade wrote:

RJsfishin wrote:
But one clue, mite be that this is a very low wattage bulb.

Any ideas ?

The situation is quite common with florescents and LEDs.
When they are "hot" with no ground, the current that leaks to ground through the AIR is enough to make a glow.

Switching the white wire is a BAD thing to do.
Why on earth did you come up with that idea in the first place ??

Most likely a better way would be to use a LOW VOLTAGE RELAY on the switch circuit.

Something like a relay coil that is 12V, use a 12V DC power supply along with your switch.

Then use common and NC contacts of the relay to operate the 120V light bulb.

Adds a little complexity, but ensures no harm can happen if the wiring to the switch is damaged in any way.

The little I know about this, I would say that this post explains it all. My guess was that this low voltage bulb (1.8 watt) was using the humid air as a return path to the panel. There just was no other path, period.
Why did I do it ??
I felt it was safer,.....because of the special switch that was being used in a position where the wire could get damaged. I felt the black wire has no chance of getting damaged, where as the white wire could. And shorting the white wire would do nothing more than turn the lite on. Damage to the black wire would cause a direct short.
But never fear, I redid the whole thing, and its good now
But I do know now that a low voltage led bulb will burn w/o a neutral or ground connected.

The switch is a n/o push button mounted in a box, that is mounted on the end of the door track.. When the big garage door is open, it bumps the push button switch to turn the light on to let me know if the door was left open,....see it from the house.

Sam Spade wrote:

RJsfishin wrote:
But one clue, mite be that this is a very low wattage bulb.

Any ideas ?

The situation is quite common with florescents and LEDs.
When they are "hot" with no ground, the current that leaks to ground through the AIR is enough to make a glow.

Switching the white wire is a BAD thing to do.
Why on earth did you come up with that idea in the first place ??

wa8yxm wrote:
Why is it burning? LED lights do not require a lot of power.. you "Broke" the white (Ground) wire but the white wire and the neutral form sort of a capacitor (NOTE the black and ground do as well).

What is happening is the load from the LED's is not high enough to "overload" the capacitor formed by all that romex between switch and light, Thus the light is seeing likely 60 volts or close to it. Possibly less.

The solution is simple.. Switch the proper wire.

you may stop reading here.

One of the issues is that We RVers live in a dual world AC and DC.. Many things work 100% on DC, and may even work will on A/C if the current is high enough.
But A/C is a different animal.. As an ELECTRONICS technician I know this, but .. well, that's the difference between Electronics and Electrical.. The parallel wires, at DC, form an open circuit

But at 60Hz it's a high value resistor.

X2

RJsfishin wrote:
But one clue, mite be that this is a very low wattage bulb.

Any ideas ?

The situation is quite common with florescents and LEDs.
When they are "hot" with no ground, the current that leaks to ground through the AIR is enough to make a glow.

Switching the white wire is a BAD thing to do.
Why on earth did you come up with that idea in the first place ??

RJsfishin wrote:
I installed a 120v led light outside on the garage, and decided to switch the white wire, instead of the black (hot) wire. All worked fine, except for when it got dark, the light burned about 1/4 brightness (good guess) w/ the switch off. The bare grnd is running in the romex, and connected to the plastic box, but is in no way connected to the porcelain fixture, except under 1 mounting screw.
Why is it burning ? I should have taken a photo, but didn't think of it.
All I do know it that I change to switching the black instead of the white, and now no lite is visable when dark. I have never seen this before. But one clue, mite be that this is a very low wattage bulb.

Any ideas ?

OK.. Not sure as to the reason you used the neutral as the place to insert the switch..

BUT it is a BAD idea in the first place and needs to be removed.

Switching the neutral presents a huge danger and should never be done, basically you have a HOT loop from the light back to the switching point.

The light is in the middle and your white neutral is hot until your switch is turned on. When the switch is turned on the neutral is now connected to the neutral of the breaker panel.

The reason you see the LED glow is from the fact that it takes very little current/voltage to make a LED glow (even just a little). The switched neutral wire coupled with the hot unswitched wire is presenting 120V AC to the LED at all times.

In AC voltages you can get what is known as "capacitive" coupling.. The switched neutral wire along with the light fixtures grounding can easily act like a capacitor and pass enough current to light the LED slightly.

"Knob and Tube" wiring was eventually abandoned partly due to the fact that the FUSE was placed on the NEUTRAL wire and not the HOT wire.. Created a danger when the fuse opened and left a very hot and live wire..

Please undo your switch and wire it correctly and your problem will be fixed.

The hot was on
Most likely there is an internal inductance aka transformer that is grounded
This produced a leaky circuit and a small amount of power into the led

Why is it burning? LED lights do not require a lot of power.. you "Broke" the white (Ground) wire but the white wire and the neutral form sort of a capacitor (NOTE the black and ground do as well).

What is happening is the load from the LED's is not high enough to "overload" the capacitor formed by all that romex between switch and light, Thus the light is seeing likely 60 volts or close to it. Possibly less.

The solution is simple.. Switch the proper wire.

you may stop reading here.

One of the issues is that We RVers live in a dual world AC and DC.. Many things work 100% on DC, and may even work will on A/C if the current is high enough.
But A/C is a different animal.. As an ELECTRONICS technician I know this, but .. well, that's the difference between Electronics and Electrical.. The parallel wires, at DC, form an open circuit

But at 60Hz it's a high value resistor.

Dr Quick wrote:
I believe that LED lights are polarity sensitive, as they are not a bulb, but a diode. They must be connected positive to positive.

OP is talking a 120V AC LED bulb.

Granted LEDs are "polarity" sensitive, but in the case of 120V AC it DOES NOT MATTER.

The reason why is the LEDs act like a diode and only conduct ONE WAY, AC ALTERNATES "polarity" so a LED would conduct no matter how you hook it up.

However, properly made 120V LEDS use ADDITIONAL circuity in the form of a full wave diode rectifier, small filter capacitor and a couple of resistors to feed the LEDs DC voltage..

Advanced 120V LEDs take that one step forward by adding in a LED DRIVER circuit which regulates the current the LED gets.

Any case the result is a 120V LED does not care as to "polarity" as in 120V Hot/neutral.

My guess is it is picking up the neutral/ground somewhere between switch and LED. Has to have a complete path in order to burn. Being dim says it is not a good/low resistance connection to neutral/grd but rather a path with a certain amount of resistance (bad connection).

Power was still on to LED....only takes 3 Volts to make an LED glow