LZW30-SN and high power LEDs

Apologies if this is well answered elsewhere and I just wasn’t able to find it.

I have a training room with a lot of LED lighting… Right around 500W according to my Sense monitor. They’re the style of LEDs that are in T8 housings. I want to use a LZW30-SN to turn the lights on/off.

500W is well above the rated capacity for LEDs, so am I going to have to use the LZW30-SN to control a higher capacity relay that actually controls the lights?

Also, why is the capacity rating for LEDs so much less than incandescent?


I’ve wondered this myself.

Dimmers also have maximum load requirements to ensure the load does not exceed the dimmer’s design limits. Surpassing these limits can result in premature dimmer failure, flickering due to noise, as well as breaker tripping. One of the main reasons dimmers have maximum loads is because of the inrush current caused by LED drivers. Inrush current is input current of short duration during initial start-up that exceeds the steady-state current value. The graph above shows the current waveform when a device is powered up.

Because of this inrush current, an LED may be rated as 25W but the actual wattage initially going through the dimmer is much higher. This means that if an incandescent dimmer is rated at 600W, you can’t assume you can use twenty-four 25W LED fixtures. A good rule of thumb is to allow 100W for each LED fixture so in this case, the 600W dimmer can handle only six LED fixtures.

Source: Minimum and Maximum Dimmer Loads for LED Fixtures | Lighting Services Inc.

Seems legit.

Thanks, this makes sense. Seems like I should be able to contact the manufacturer and get a spec for the inrush current on my bulbs easily enough.

My statement of roughly 500W is real world via my Sense monitor, which aligns well with the bulb spec of 504W (18W*28 bulbs). The Sense device certainly can see inrush but I don’t think the view it exposes to the user has enough resolution to see it.

And FYI, this is an on/off switch, not a dimmer. When I ordered it I didn’t even consider capacity since it wasn’t a dimmer. Oops.

Ahh…missed that it was the on/off switch. Sorry about that. I would imagine it would be a similar issue with the inrush current of the load itself.

That is one possibility. You’d have to cut the light string up into segments and use a smart relay to make and break power. You could then control the relays via scenes or maybe association. The downside to that is you are not directly controlling the lights, relying upon the relays to function properly.

An alternative, depending upon the access you have to the fixtures and wiring space would be to cut the fixtures up into segment(s), and run feeds down to the switch box. You could then cut that switch box out and replace it with a multi-gang box, adding smart switches for the new segment(s).

You could then “synchronize” the switches via a scene. With this setup, even if the scene goes south, you still have a switch that will directly control each segment.

I’m not an expert in LED technology, but my general understanding is that since LEDs use drivers, there is inrush current that has to be taken into consideration. So and LED that draws X Watts might draw X + Y Watts on startup. So switches and dimmers have to take that into account. It’s a little more complicated than that, but I think that’s the general idea.

Nah my plan B is much simpler than that. I get a dumb AC to AC relay, put it in a box in the attic, and use the Inovelli switch to trigger the dumb relay on/off. The actual lights get connected to the dumb relay. Easy. I just lose the power monitoring capability of the Inovelli… Unfortunate but not the end of the world.

Yep, that’ll work as long as the relay supports that load!