Higher Load Switches

I recently ran into a problem when installing a second generation switch on a circuit with Christmas lights and heat tape.
After awhile, the relay would become stuck and I was no longer able to control the switch manually or remotely. After further research I found that these switches could only do 600W maximum. Seems low compared to other switches that offer a 1200W maximum.
I could foresee this being a problem with exhaust fans or other high amp loads like the circuit I had.
I hope to see the next switches contain a higher load rating. What do others think?

(Edit) I should note that these load ratings and my setup was with all the tabs intact.

I don’t know if this is true for the Inovelli, but for other smart switches, the resistive rating is separate and usually higher than the incandescent load. You mentioned a 600W max. That’s for an incandescent load.

Perhaps @Eric_Inovelli can comment on whether or not the resistive load max for the switch would be higher than the incandescent rating. In your case, the heat tape would be a resistive load.

And just so you’re aware, the heat sink tabs on the switch are cosmetic. It doesn’t use them, so whether or not they’re in place does not affect the load rating.

Yes, great point! Please see the specs here for reference:

  • 600W Incandescent, 300W LED, 150W CFL
  • 300W Inductive Load (for exhaust and/or ceiling fans)

Correct, for the On/Off switches they are cosmetic. The reason they are there is because the On/Off and Dimmer switches use the same tooling so rather than creating a separate mould, we opted to just use the same one for efficiencies (the dimmers need the heat sink tabs and it does affect the wattage if you remove them).

We’re looking to completely remove the tabs in the future as other manufacturers have started to do.

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Right, but what about RESISTIVE load? For other manufacturers, that’s a different rating than the Incandescent, and typically higher. Your specs don’t publish that.

Thanks Eric for responding
I know that incandescent, LED and CFL all have different wattage ratings. I do see that many of other Zwave switches are currently almost double the rating for any load. Hoping that the next gen switched can follow suit.
Thanks

(Edit). I’m probably pulling 700-800 Watts on the heat tape, probably should’ve looked into the manual a bit further before installing Ha!

@Bry – my bad :confused:

I just looked on the On/Off switch metal plate and it says: 1200W Resistive so I’ll update the spec sheet!

For people that have very limited electrical knowledge (ie: me) what does this mean?

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@Eric_Inovelli
I’m not an expert electrician either but I believe this is referring to a higher resistance load. These loads are most commonly found on stuff like electrical heaters

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Loads consisting of any heating element are classified as resistive loads . These include incandescent lights, toasters , ovens, space heaters and coffee makers.

-google

Incandescent bulbs do have an initial “inrush” current. Their resistance is much lower (therefore current higher) when the filament is cold. This is only for a very short time, it looks like they can take up to 10 times their steady state power usage, but for a few hundredths of a second.
So incandescent bulbs (despite what google says!) aren’t exactly simple resistive loads. Presumably that’s why the lower rating (600W incandescent vs. 1200W resistive).
But then @jaxonstagecrew’s use case should be within specs, so why isn’t it working?

What they said ^. Resistive varies from inductive because of differences in the AC waveform, consequently dictating different load requirements. The thing I don’t understand is that smart switches have max ratings for resistive loads which are typically higher than the ratings for incandescent, LED, etc. Heating cables, LEDs, Incandescents and CFLs are all resistive loads, but I don’t know why the max ratings are different.

My guess is having two different types of loads on the same circuit. Incandescent drawing a whole bunch and the heat tape

Hi @Bry, I can see the different rating for incandescent (that initial “inrush” current when the filament is cold). CFLs apparently have a nasty inrush requirement also (presumably thus the low rating). LEDs are more variable. I’m also guessing that the limit for “inductive” isn’t really anything to do with inductance, but they are expecting it to be a motor, and they have a significant inrush/startup current and it lasts longer.

Hi @SandyB That may very well be. It makes sense! I typically associate large inrush requirements with motors but I see now that incandescents as well have a fairly hefty requirement until the filament heats up.

Pretty much everything except simple resistive loads have inrush :frowning: Pulling from some general knowledge:

  • Basic Resistive Load: You have steady resistance X, which draws steady current Y. Electric heaters are good examples of this, though even they do have some inrush depending on the heating element material, but it’s usually not a significant % of the nominal wattage.
  • Basic Inductive Load: It’s like adding a flywheel to a resistive load. Lots of current to get it going. Once it’s going, it’s easy to keep going. (It also doesn’t want to stop, and that’s a separate problem…). Motors are good examples of this (Vacuum cleaners, fans, etc.) and anything with large transformers inside.
  • Basic Capacitive Load: Initial inrush as the capacitors charge up. Many low-power, fixed-current LED drivers are capacitive loads, such as the ones typically found in screw-in LED bulbs.

Every load is usually some combination of the above, or has additional properties that make it an issue compared to a basic resistive load:

  • Incandescent Load: Technically a resistive load, but tungsten has enough variance in its resistance due to temperature that the current draw when cold is significant, causing inrush.
  • CFLs: Technically an inductive load, but additionally an extremely high voltage is required to initiate the arc between the electrodes in the bulb. With the help of the ballast in the CFL driver, this translates to a high inrush current.
  • Electronic devices with “Switched” or “ActivePFC” power supplies: Capacitive+Inductive Load. Pretty much anything with a separate power “brick”, Computers, USB chargers, TVs, and many other major electronics today. These have a high inrush both to charge up the capacitors, and to get the load going. The USB chargers aren’t usually an issue, but if you’re switching on 300W of LED strip lighting or a 750W desktop computer, there’s going to be some inrush.

If you have multiple types of loads connected to a single circuit, figure out what % of the total for each type you’re using, and don’t go over 100%. So if you’re using 800W of 1200W (66%) of resistive load, then you shouldn’t add more than 50W (33% of 150W) of CFL load or 100W (33% of 300W) of Inductive/LED load or 200W (33% of 600W) of Incandescent load to the same circuit.

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Thank you for explaining. This was definitely my problem then