try taking all the light bulbs out so they wont overload the circuit.

It would take quite a lot of cellar lights to overload a circuit. Besides, by code, your furnace should be on its own circuit, so I'd expect any problems to affect much more than just the lights in the cellar.

The failure of the lights and the furnace may or may not be related. If your furnace repair person was right, it certainly wasn't related the past two times.

Check the main panel breakers to see if you can restore the lights and/or furnace. Flip each one off and then on in turn. If you don't get any improvement, it's time to call in an electrician for at least the lights.

You say the second time the HVAC guy fixed your furnace he replaced the HSI(hot surface ignitor)

What did he specifically fix the first time he came out with the furnace quit running.

Okay first off. Troubleshooting. Nobody cares about code. We care about what's there. "the last guy" may very well have ignored code, or the installation may be so old that whatever code we want to apply didn't exist at the time.

Option 1 - they're on the same circuit, which is running close to its limit. I'm doubting this. I'm assuming the furnace guy would have just reset the breaker (or replaced the fuse) and been done with it.

Option 1a - similar to option 1, except the furnace guy replaced the "HSI" because he thought it was somehow causing the overload/fault.

Option 1b - same as 1a, except that the reason for replacement was to look like he actually DID something and thus make some extra cash.

Option 2 - HSI failure is truly CAUSING a fault, and tripping breaker, which also powers basement lights.

Option 3 - Basement lights and furnace are wired together in some bizarre fashion that allows one of the furnace's safety devices to turn off the basement lights as well.

Option 4 - Loose neutral connection somewhere in the electrical system (service itself, or possibly basement lights & furnace on MWBC or subpanel?), fault on one side fries stuff on the other.

Would this HSI be the same as the electric ignition that starts the furnace? When I first moved into this house in 1985 the handyman (most Real Estate have their own handymen to do any maintenance work on the houses that they sell. This handyman redid the wiring for the basement (said that the wiring was old and dangerously done. I'm now not sure that this guy was qualified to do any electrical work but that happened years ago in 1985. Right now I have the problem of trying to figure out just whats wrong that's causing me to always lose my furnace and all the basement lights. I appreciate all your imput. I think the last person to write a thread makes a lot of sense. I'm going to print out this thread and show it to the electrician. I have $180 saved to pay the electrician. If any one else cares to add to this thread, please do. I can use all the information I can find. Thank you. Margaret

davidr:wouldn't the fact that the circuit breakers are shutting off mean that there is some kind of problem that's causing the breakers to switch off? Maybe just flipping the breakers on and off to re-start everything won't really solve the problem?
pharkus: I read all your options. It sounds really scary, do you think a qualified electrician would be able to fix the problem? Thank you. Margaret