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jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
Went through some miscellaneous bulbs the other day. Found an LED bulb labeled “not compatible with dimmers, timers or photocells”. What good is such a bulb? Dimmers are more of a minor issue but we have lots of lights on photocells & a few on timers. Add this to the issue of various bulbs being discontinued & it’s a huge mess just to keep spare light bulbs. Technology is supposed to help us but this is madness.
 
Little Bill

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
AC\DC said:
Why would a timer play an negative effect on a bulb. How is it different from just turning you switch on and off.
Click to expand...
I know that I found out that photocells have to be rated for LED. It was explained to me by the SH that the in-rush current of the LED requires a "beefier" made photocell. That may also be the reason for a timer needing to be rated for them.
Having said that, I don't know why an LED would say not to use them in a PC or timer. Seems to me, if these devices are rated for LED they should work in them.
 
synchro

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Maybe the concern is with devices that do not use a neutral, but instead depend on having a small amount of current flowing through the load to keep the device operational when it's in the "off" state. If the current drawn by the LED suddenly drops to zero as the applied voltage is lowered, leaving no portion of the I vs. V load curve to supply a minimal operating current in the "off" mode, then the device might not work properly. Perhaps the LED mentioned by jmellc has such a characteristic. This is speculation on my part, but I can see that this could be an issue with certain LEDs.

Some devices have used the equipment ground as a return path for powering the electronics of the device, but this is limited to less than 0.5 mA by a UL standard. One would think that a timer or photocell could be designed to operate using such low current levels, but I believe there are many devices out there that depend on some current through the load when they are in the "off" state. Dimmers are more challenging without a neutral, because a stable and accurate reference for determining the zero crossings of the AC waveform is desired to prevent flickering.
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
This is not a new issue. It's been close to 4-5 years that they finally came out with photocells rated for LED lighting. When led bulbs first came on the market many were not rated to be dimmed and some could not be in an enclosed fixture. I would think by now that has changed but I don't know if it has. I am pretty sure that the big box store only sells dimmable led and those rated for enclosed fixtures....

Even Lutron has a list of light bulbs that were tested with their dimmers as all led's are not created equal. They will only guarantee the bulbs that they tested.
 
J

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
All good thoughts. My thought is that any manufacturer of bulbs should make the bulb compatible with all commonly used switching devices. All manufacturers of switching devices should make them compatible with all commonly used bulbs. A huge portion of new lighting is LED and growing.
I see this as a similar issue to all switch boxes being sized to fit all switches & receptacles. Any deviation should be the exception rather than the norm. The manufacturer himself benefits by this. If your product is easier to use, it is the one I will look for.
 
J

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
Dennis Alwon said:
This is not a new issue. It's been close to 4-5 years that they finally came out with photocells rated for LED lighting. When led bulbs first came on the market many were not rated to be dimmed and some could not be in an enclosed fixture. I would think by now that has changed but I don't know if it has. I am pretty sure that the big box store only sells dimmable led and those rated for enclosed fixtures....

Even Lutron has a list of light bulbs that were tested with their dimmers as all led's are not created equal. They will only guarantee the bulbs that they tested.
Click to expand...
Good info Dennis. The enclosed vs open fixture is another point I should have included.
You stirred a thought that it might be good for device makers to arrange bulb branding of bulbs. Lutron gets bulbs made for their devices that carry their name. As a buyer, I know to get Lutron bulbs for Lutron devices. Same with Cooper & LeGrande. Extra feather in your cap if you can truthfully state “also compatible with …….”.
As the world gets more complex, certain simplicities are ever more needed.
 
R

retirede

Senior Member
Location
Illinois
AC\DC said:
Why would a timer play an negative effect on a bulb. How is it different from just turning you switch on and off.
Click to expand...

Perhaps timers with solid state switching (as opposed to mechanical contacts) won’t play well. Some lights continue to glow dimly with such a device.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
synchro said:
Maybe the concern is with devices that do not use a neutral, but instead depend on having a small amount of current flowing through the load to keep the device operational when it's in the "off" state.
Click to expand...
That be my thoughts as well. Most the photocells and timers we commonly use aren't that way, some already installed in consumer grade products might be like you mentioned though.

As far as contact rating and higher inrush, that has pretty much been an issue for some time because incandescent lamps also have an inrush as well as anything with a magnetic transformer/ballast, they maybe just not actually been tested and listed and marked for these LED drivers is all.
 
H

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Standard everyday photocells require a small current to operate during the daytime when the light is off.
LEDs work on such low voltages this causes the LED to flicker, causes interference with other devices, and causes the LED to degrade faster than normal.
 
grich

grich

Senior Member
Location
MP89.5, Mason City Subdivision
Occupation
Broadcast Engineer
retirede said:
Perhaps timers with solid state switching (as opposed to mechanical contacts) won’t play well. Some lights continue to glow dimly with such a device.
Click to expand...
The LED light bubs (C7 size) I have in radio studio on-air signs will run at half-brightness with the voltage leaking through the sold-state relay that switches it.

For now, I loaded an incandescent C7 bulb into one of the sockets. That extinguishes the LED lamp. I suppose I could install a mechanical relay, or place a right-sized resistor across the SSR load terminals.
 
James L

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
jmellc said:
....Found an LED bulb labeled “not compatible with dimmers, timers or photocells”. What good is such a bulb?
Click to expand...
Garage ceiling, garage door opener, unfinished basement, closets, pantries, laundry, and probably another half dozen rooms that aren't typically on a dimmer, timer or photocell 👍

I don't know about the timer or photocell prohibition much, but all the big box stores sell non-dimmable LED bulbs
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Hv&Lv said:
Standard everyday photocells require a small current to operate during the daytime when the light is off.
LEDs work on such low voltages this causes the LED to flicker, causes interference with other devices, and causes the LED to degrade faster than normal.
Click to expand...
Only if the photocell would happen to be in series with the load, if one that connects the logic components across the line but has a separate circuit branch with a contact for the load this shouldn't be an issue. That is what the majority of the all purpose photocells most of us use are. The other style is more of something internal to an assembled item and not a general use component.
 
Speedskater

Speedskater

Senior Member
Location
Cleveland, Ohio
Occupation
retired broadcast, audio and industrial R&D engineering
At the house, I have several old X-10 remote controls. Each receiver controls a single 15, 25 or 40 Watt incandescent bulb. None of the receivers will operate with a LED bulb.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Speedskater said:
At the house, I have several old X-10 remote controls. Each receiver controls a single 15, 25 or 40 Watt incandescent bulb. None of the receivers will operate with a LED bulb.
Click to expand...
put one incandescant in with a bunch of LED's on same control though and I bet it works.
 
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