Selecting a Solid state relay for a 1HP 120VAC motor

I have a customer with a 1HP 120VAC pump ùsing a smart device to time and control it.

Another person has tried some generic 25A 250V and 40A 380V SSRs with all failure. One 25A unit faled-open, one failed-closed(shorted), and the 40A unit failed-closed. All had heat sinks with proper compound.

I have assured this new customer that we can provide a reliable permanent solution, using an Opto22 product by an American company.

What will be the best O22 SSR product to use for this application? And what additional support components might be necessary to use with an inductive load such as this motor?

Hi Ed. Welcome to the Opto22 Forums.

If you have not done so already, please review the SSR data sheet.
Take note of the many sections at the end of the guide as there are lots of calculations and considerations in selecting and sizing the relay for your application.

I heard back from an Opto22 applications engineer this morning.
It seems that Opto22 does not have an SSR large enough for a 1HP motor application.
So now I’m looking for a manufacturer that does.

That seems strange to me, 10 amps max - maybe it is some other requirement you have?

Just one of the zillion awsome things about Opto… .We are not going to sell you a product that cant do the job just to make a sale.

Side note… I monitor my power consumption at my house (with Opto gear of course). I have just built a solar powered UPS (6Kw) with 10kWh battery backup. The amazing surge that the system sees when any of the three refrigerators turns on is pretty crazy. From what I understand from a mate that has well water, his pump has a very similar crazy peak spike on startup. Motors pull all sorts of quick amps on start up. I am not surprised that some of the other relays failed closed (welded shut) or open (blown apart internally).

I wish you the best in your search.

I know this is posting another company’s product but I have used the crydom DR4560D60 for some heating applications that require more power than the OPTO22 SSRs. The datasheet says it is 2HP rated at 120VAC 1phase. Watlow may have some SSRs as well but they seem to specialize in heating applications.

here is a link:

I received an email back from Crydom Sensata, they indicated their D1225,-10 SSR would be recommended. (

I ordered one from Allied to test.


I just built a 3kw solar system for my house with a 5kWh battery. I use it to run the refrigerator, freezer and all the lights and outlets downstairs. I’m using some old Opto hardware (LCSX Plus/B3000) to monitor it that I’ve had on a shelf for about 15 years. I powered it up the other day and it still works like it was new. I’m working on the modbus to the inverter/charger but it’s not outputing the high register for watt readings. Seems to be a bug in their firmware so I’m putting on shunts and reading them from some AIV modules. Was there ever a modbus kit for Factory Floor? I’ve been rolling my own and got the slave modbus working but still need to work on the master modbus.

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I don’t believe so. That said, I don’t think it would be that hard to copy/paste from the PAC Control chart to FF. You only want the polling sub, so yeah, it should be pretty straight forward.

Due to a lack of time to tinker, I went the (rare for me) paid route and bought Solar-Assistant.
It polls the Modbus on the Inverter and the two BMSs and gives me pretty graphs.

SA also has MQTT, so I used Node-RED to pull the data into groov View so I can mix it in with other data (like solar radiation from Opto’s weather station).

Anyway, we are very very off topic…