Wiring sparked when removing baseboard heater while main was off (2023 Update)

I recently bought a house with old baseboard heaters so I began replacing them one by one. When I started to remove the second one, and I removed the wire nuts and separated the wires and pulled the heater away from the wall I got a good spark. So much so that it left black in the neutral wire end. I freaked out, thinking that somehow I must have forgot to turn off the breaker. So I turned off the main and continued with replacing the unit with a cadet. I did several more without incident, then on my last one, with the main OFF, the same thing happened! Can anyone explain why this might have occurred? I read somewhere that baseboard heaters carry a charge at all times, power or not, but I don’t know if that’s even possible. I’m not an electrician so I’m really baffled and now rightly afraid to try to wire in the new cadet heater.

It sounds like you experienced some unexpected sparks when removing and replacing your baseboard heaters. This can be concerning, especially if you're not familiar with electrical wiring. Here are some possible explanations for what might have caused the sparks:

Live wires: It's possible that one or more of the wires was still live, even though the main was turned off. This could have happened if there was a secondary source of power, such as a generator or a backup battery system.
Loose connections: The sparks may have been caused by loose connections in the wiring. Over time, the connections can become loose, which can cause sparks when they're moved or disturbed.
Circuit breaker: It's possible that the circuit breaker was not working properly and was not completely shutting off the power to the baseboard heater.

Given the potential danger of electrical work, I would recommend contacting a licensed electrician to help with your project. They'll be able to diagnose the issue and make any necessary repairs to ensure your safety and the safety of your home.