There are fake SSR's out there that are not UL rated, here's an ebay listing for a PDI package that includes a thermocouple and a fake SSR, be careful of what your buying.
http://www.ebay.com/itm/261286976034...%3AMEBIDX%3AIT
Here's a link with details and good photos showing what to look for.
http://canada.ul.com/safetyalerts/ul...lease-13pn-52/