It's fine for it not to be running at full power. If you have a proportional thermostat that's how it works. But 80% power doesn't equal safe. My 80w at full power got up to around 240°F. So if it was on a cheap thermostat and dimmer set to 80% and the thermostat failed on you, you are still looking at around 190°F. Still gonna cook your snake. Just don't want you having a false sense of security with that dimmer. I don't see a problem with using it just don't see a benefit either.

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