Motion Sensor blows up

[sparkmatic]

So /we have motion sensors through out my site that power T5 fixtures single lamp, that are 240V to ground. The sensor is rated for 120/230 (single phase), 277,347. I do not see any issue with the voltage but for some reason from what I have found out that this is not the first time the sensor smoked on someone. For me it happened after I restored power, the lamps came on for about 10 seconds then the sensor let loose

I then did some checks found nothing grounded but replaced the wiring and lamps (these are fixtures that come pre set up with cables that plug in either side of each fixture (encapsulated)not my choice just whats here.

After the rewire the lights work and have worked for a few days now. Hope this makes sense.

My main question is has anyone had this kind of issue? I don't want to put the manufacture out there as it may not be their issue just don't see an issue that should cause these smoke (violently)

Thanks

 

[tortuga]

Years ago I had something similar happen older office building with EMT and BX cable with no green wire, 120v lighting, brand new motion sensors installed on existing fixtures, none worked replaced them none worked again. Supplier said we smoked em' and voided warranty.
Someone figured out we had to pull in a wire type equipment ground to get the motion sensors to work as they actually were using the equipment ground as the return for the sensor. How that got UL approved is beyond me. I would be suprised if sensors are still made that way in 2024.

 

[Eddie702]

Not my are of expertise but would it be better to have the motion sensor close a relay to switch the lights?

 

[ptonsparky]

Not my are of expertise but would it be better to have the motion sensor close a relay to switch the lights?

Yes, especially if reaching the limit of the controller.

 

[hillbilly1]

Years ago I had something similar happen older office building with EMT and BX cable with no green wire, 120v lighting, brand new motion sensors installed on existing fixtures, none worked replaced them none worked again. Supplier said we smoked em' and voided warranty.
Someone figured out we had to pull in a wire type equipment ground to get the motion sensors to work as they actually were using the equipment ground as the return for the sensor. How that got UL approved is beyond me. I would be suprised if sensors are still made that way in 2024.

They still make them, but plays havoc with gfi/afci circuits if to many are on it. The current draw is very low.

 

[James L]

they actually were using the equipment ground as the return for the sensor.

Many dimmers and other controllers are still made this way.

And I had an issue like @hillbilly1 mentioned. I had about a dozen on a dual function circuit, making it trip.

At my church we have school gymnasium bathrooms with occupancy sensors, and one doesn't consistently work well. It's using the conduit for the ground, and there are numerous places where the fittings are loose. Some covered by drywall. No bueno

 

[tallgirl]

They still make them, but plays havoc with gfi/afci circuits if to many are on it. The current draw is very low.

I thought I saw that UL threw its hands up in the air because of the lack of neutrals in some boxes?

 

[tortuga]

I thought I saw that UL threw its hands up in the air because of the lack of neutrals in some boxes?

I'd ask UL whats the difference between using a grounded circuit conductor as an equipment grounding conductor (EGC) and using a EGC as a grounded circuit conductor? Why not then just make a 2-wire romex with a black and a bare and wire everything that way?

If the installer can't run a neutral to an existing switch box (switch leg box) use a device with a battery, pizo & wifi, bluetooth or plain old low voltage cable, PoE etc .. etc.
there are so many options in 2024 there is no need for any device, to use a equipment grounding conductor as a grounded circuit conductor.

In the 80 & 90's I remember timers for switch leg boxes that were powered by leaking a tiny mA level of current thru the load, just to power a timer or indicator light. But the load had to be incandescent so it was like a series resistor.
That worked fine until the CFL's came out, then the leaking thru the load no longer worked as that would charge the starting cap and the lights would blink on every time the cap charged.
I think it was around this time they got the idea to use the EGC.
In 2023 with all the expanded GFCI requirements and all the tech we have you'd think by now there would be a very clear code section that says an EGC cannot be used as a grounded circuit conductor. I suppose one could argue the definition of EGC and 110.7 covers that.

 

[hillbilly1]

I'd ask UL whats the difference between using a grounded circuit conductor as an equipment grounding conductor (EGC) and using a EGC as a grounded circuit conductor? Why not then just make a 2-wire romex with a black and a bare and wire everything that way?

If the installer can't run a neutral to an existing switch box (switch leg box) use a device with a battery, pizo & wifi, bluetooth or plain old low voltage cable, PoE etc .. etc.
there are so many options in 2024 there is no need for any device, to use a equipment grounding conductor as a grounded circuit conductor.

In the 80 & 90's I remember timers for switch leg boxes that were powered by leaking a tiny mA level of current thru the load, just to power a timer or indicator light. But the load had to be incandescent so it was like a series resistor.
That worked fine until the CFL's came out, then the leaking thru the load no longer worked as that would charge the starting cap and the lights would blink on every time the cap charged.
I think it was around this time they got the idea to use the EGC.
In 2023 with all the expanded GFCI requirements and all the tech we have you'd think by now there would be a very clear code section that says an EGC cannot be used as a grounded circuit conductor. I suppose one could argue the definition of EGC and 110.7 covers that.

LED’s are even worse, I’ve had to sneak in an incandescent lamp in multi lamp fixtures to keep them from flashing when dimmed. Some of the newer have a green sleeve to slide over the white neutral from the switch, when used where the neutral is not available.