I was chatting with /u/bladebaka about kiln retrofitting and for kicks I looked up the SSRs that he purchased. The happened to be the same make of SSRs that I have been using and it turns out that there is a shittonne of counterfeit SSRs impersonating the FOTEK brand but containing triacs that are well below the nameplate spec on the SSR.

The triac is a kind of transistor doohickey which is the main current carrying component which switches current on and off to your elements. They are the most expensive component within a SSR and the cost of this component basically is what makes a 40A SSR more costly than a 25A SSR.

Underwriters Laboratories (UL mark) has noted this problem:

https://www.ul.com/node/81246

And other hobbiests are running into this issue with high amp applications:

https://protosupplies.com/inferior-counterfeit-fotek-ssr-25-solid-state-relays-on-the-market/

I just opened up my fairly recently built kiln controller to take a look at my FOTEK SSRs and I find that both of them are counterfeit based on a look at labelling. I have a third 60A SSR that is also counterfeit.

I busted one of them open to take a look inside and it doesn't look good. The conductors are way too small for a 40A SSR. I'll take it to work and desolder the triac so I can take the board out and look at it's specs, but so far it really doesn't look good.

Solder work is poor. I see melt marks in the case from sloppy solder iron work. The board is not potted in conformal coating which is a typical measure done in good SSRs. The gaps between circuit board traces does not look right for a 380V rated device which does not have conformal coating.

I think I got away with it because I've only got a little test kiln requiring 10A per element pair and I went with 40A SSRs which I heat sunk well with a fan because I am paranoid. I'll get a spec on the triac tomorrow but so far things look terrible.

3 out of 3 SSRs sourced (two Amazon, one from a local business) are definitely counterfeit. I'll find out how badly underspec'd the triac is tomorrow, but it's conductors sure don't look right for 40A.

FOTEK appears to be a frequently counterfeited brand on Amazon, but as I see it, everyone on Amazon could be selling SSRs that have nameplates that do not match the triac specs. We should not be buying critical current carrying components on Amazon.

Instead trust Mouser or DigiKey. Triacs get stuck "on" when they fail which will overfire an entire kiln load when your control system gets locked "on". Even worse, your SSR may overheat and catch fire.