Track lighting frustrations...

[sw_ross]

Related to track lighting where the track is mounted over top of a flush mounted j-box w/mud ring, the track pigtail gets spliced to the conductors in the box then snapped onto the track that is installed over the j-box, then the plastic cover screws on.

How the heck are you supposed to access the wire nuts (for troubleshooting, etc) once the track is mounted over top of j-box?!!

I was troubleshooting some track lighting today that had the LED bulbs periodically flashing. I was attempting to follow the circuit around looking for a loose neutral.
(6) 8 foot tracks with line voltage LED MR16 style lamps. Tracks switched in 2 groups of 3, with LED dimmer on each set (and set up for 3-way).

The circuit is set up as a multi-wire with 2-pole breaker.
Each circuit (3 tracks) would randomly flash for ~60 seconds, the other set of tracks (other circuit) would not be flashing at the same time.

My assumption is either a loose neutral or an issue with the dimmers (both in same box)?

My main frustration was accessing the wires in the junction boxes!!
RANT OVER!!

Any input is always welcome!

 

[Dennis Alwon]

You have to loosen up the track and the head to get to it.

We never use a box with a track. We use the live end feed and wire directly to it. I know that sometimes we have to in existing situations but there is no way to get at the connection without taking the fixture lose.

How do you get at a surface fixture connection? You take the fixture down.

 

[JFletcher]

I thought it was a code violation to put up any kind of lighting it is attached to other than junction box that conceals or covers the junction box... Don't know about track lighting but fluorescent fixtures/troffers cannot conceal the junction box.

 

[blkmagik21]

Was this a Juno track? Because the track heads go out in those all the time.


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[sw_ross]

Not sure of brand

Not sure of brand

These were installed about 6 years ago by another electrician. Not sure of brand.
I was mostly focused on trying to look for a bad connection somewhere.
I feel like it has to be somewhere in the neutral path of current since both circuits are experiencing the LED flashing syndrome!

I've always heard about the dreaded LED flashing syndrome, this is the first time I've experienced it. Whenever I read about it it seems like it has to do with loose neutrals.

What would cause the 2 circuits (MWBC) to flash randomly but independent of each other?
If there was a neutral issue common to both hots you'd think they would flash simultaneously?

 

[blkmagik21]

Would they? If it’s a mwbc and it’s wired right then both circuits should be on separate phases. So they are getting power at exact opposite times


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[GoldDigger]

Would they? If it’s a mwbc and it’s wired right then both circuits should be on separate phases. So they are getting power at exact opposite times


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A common misconception. For single phase 120/240 three wire the L-N voltages are of opposite polarity, but the peak voltages still coincide in time. So each side of the MWBC will deliver power to an identical load at exactly the same time.
The voltage is a symmetric sine wave at 60HZ. The I²R power is a vertically offset 120Hz sine wave running from zero to peak power.
This is the reason that the normal running "flicker" for strobe effect of incandescent or magnetic ballast fluorescent will be at 120Hz rather than 60Hz.

If the load contained a half-wave rectifier you would have a valid point.

 

[kwired]

Would they? If it’s a mwbc and it’s wired right then both circuits should be on separate phases. So they are getting power at exact opposite times


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Besides what GD mentioned, they have a common conductor between them. If that conductor is open or has high resistance at a junction - it doesn't just increase resistance for one side of the circuit only.

 

[sw_ross]

They don't flash in an alternating pattern
One set of tracks will flash for ~ a minute, then it stops, a random amount of time will pass before another event. Then if it starts back up there's no guessing as to which set of tracks will start flashing again.

Yesterday I was there and one set of tracks flashed on two separate events, never saw the other set flash. The day before the manager said the same thing happened with the other set. Totally random.

Only thing i can see in common between the two sets of track is the neutral.

 

[mkgrady]

Today I did troubleshooting on led wafer lights. The lights would randomly flicker. The dimmer was on the list of approved dimmers. I changed the dimmer and it did the same thing. Then I tried a dimmer that was for incandescent or halogen but not led. That fixed the problem. I don’t understand why

 

[GoldDigger]

Today I did troubleshooting on led wafer lights. The lights would randomly flicker. The dimmer was on the list of approved dimmers. I changed the dimmer and it did the same thing. Then I tried a dimmer that was for incandescent or halogen but not led. That fixed the problem. I don’t understand why

1. Always look for a dimmer with a three wire (line/load/neutral) configuration to avoid dependence of operation on load voltage characteristics.
2. Compatibility lists are often not updated after product changes.

 

[sw_ross]

Hmmm, interesting...

Each set of tracks is on a dimmer switch. Just your typical Lutron. It's rated for LED. Doesnt use a neutral. What type of dimmer are you referring to?

I was also wondering if the dimmers were getting hot, they're both in the same box.
I told the manager if the issue continues I would change out the dimmers for standard 3-ways to see if it changes things as an experiment.

 

[mkgrady]

Today I did troubleshooting on led wafer lights. The lights would randomly flicker. The dimmer was on the list of approved dimmers. I changed the dimmer and it did the same thing. Then I tried a dimmer that was for incandescent or halogen but not led. That fixed the problem. I don’t understand why

Lurton AY-600P. First I bypassed the dimmer. That made the flicker stop. Switched to this dimmer and it works fine. Full range of dimming. I don’t get it

 

[blkmagik21]

Something to check on the led dimmer is the trim settings. If too low then you will get flickering.


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[GoldDigger]

Hmmm, interesting...

Each set of tracks is on a dimmer switch. Just your typical Lutron. It's rated for LED. Doesnt use a neutral. What type of dimmer are you referring to?

I was also wondering if the dimmers were getting hot, they're both in the same box.
I told the manager if the issue continues I would change out the dimmers for standard 3-ways to see if it changes things as an experiment.

Early phase shift dimmers operated entirely from the drop between the line voltage and the load voltage during the time the pass element in the dimmer was open. Among other things, with tungsten filament bulbs the great difference between the cold and hot filament resistance causes the hysteresis effect in which you have to raise the dimmer will above the lowest stable dim setting to get the bulb to restart, then turn the dimmer back down to get a lower output.
Not all three wire dimmers use the neutral. To make them usable in existing switch boxes without a neutral present they instead all used to use the green wired (EGC) as a return path for normal operating current of the dimmer circuit itself. Thankfully that mode of operation is being phased out.