Incandescent light bulb some time are used on chicken egg incubators. And on a paper dry box (?).
8A at 12VDC is more harder to handle that 100W at 220VAC (0.45A).
Both can hurt you and start a fire.
SSR like Fotek SSR25 have only the screws exposed, if used correct terminals, it is very safe. Relay modules have solder pad and other dangerous parts exposed.
So you buy relay modules with bases http://www.ebay.co.uk/itm/MY2J-AC-12V-C ... 1520106608
. The contacts are no more exposed than on an SSR.
You will need a transistor to drive the relay, but you also need to read the spec sheet for your SSR closely as some won't trigger reliably on 3.3V (SSR-25 claims min ON voltage of 2.4V, so should be OK). SSRs typically have a higher on resistance than relays, so you may need to mount on a suitable heatsink if switching high currents.
Horses for courses. See https://en.wikipedia.org/wiki/Solid-state_relay
for advantages and disadvantages of SSRs.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.