in the breaker box.. not a big deal especially if not putting the clamp on the mains. as you can shut the main breaker off and just put it on two of the wires going into the dryer circuit.
i also have another unit on the mains to monitor the whole house. that is a little more hairy
I have a feeling that these clamps are a LOT smaller that I am imaging so I might have to give it a try. The phone idea above in the mean time is a cheap and dirty solution that seems to work OK... I just hope one day I do not see my phone on the floor from being vibrated off the top of the dryer! LOL
What got me interested in the Aeotec DSB28-ZWUS is the price on Ebay --> $25. So I thought I would give it a try. Just wanted to make sure it works in Hubitat. It is recommended here but was interested in if it works with the standard driver you get when you discover zwave or Hubitat has something else I need to know about for it.
You might consider a battery powered temperature sensor attached to the vent pipe exiting the dryer. Once dryer completes cycle the temp at this sensor should rapidly fall..... A bit safer than messing around with mains wiring.
you dont need to do mains you just need to put one set of clamps around the dryer circuit breaker wires.. easy to do as you can turn the main off first. or you can even put them around the wires coming out of the dryer as most dryers you need to wire in a pig tail anyway as they are not included as outlets vary,
probably actually less work than trying to tap into the vent pipe and not have a leak or swap batteries in the sensor, and in addition probably not reliable say for low heat delicate loads etc.
another option i tried is a shock sensor and that also not reliable for me.