I am building an extra 330 with a 100 CC engine. I have heard some horror stories about planes with engines running but transmitters not operating for various reasons, but mostly pilot error, creating a dangerous condition. I have been considering an ignition kill switch for my plane for safety reasons and need advice.
I feel like if I install a kill switch it should be of the optical coupled type and not servo operated. Is this extra expense that will never be used or do most IMAC models have these devices? I see what I think is a good switch selling for about $60.00. Am I overlooking something better at a lower price? Which switch on the transmitter is best to operate the kill switch?

123crash

I'm a newby gas guy, but my first 50 size has the fiber optic kill switch, and the 100 powered 33% Edge I'm building now will also have it.

You'll get a number of answers about this, but IMHO a kill switch is just a really good idea. I think that if you're building something that size, the extra for the kill switch is nothing for the safety factor it offers. Mine are setup, and I test them to assure that in normal circumstances it works, so that closing the throttle will kill the engine. Then I add the kill switch to the same switch on my transmitter that I've used since I started flying glow stuff, which closes the throttle and activates the switch on channel 9 of the receiver.

Use which ever switch you've been using so far to avoid confusion.

Even though most modern ignition modules will shut off after a certain period of time where the trigger has not passed the sensor, if the radio is off, there's no power to the ignition so I figure there's an extra safety factor there as well.

Thanks for confirming my thoughts about installing the kill switch for the added safety it provides.
123 crash

I sent you a PM about setting up variations of reduntant kill swithches to answer your second paragraph. Your first statement about loss of signal is good reason for using a PCM receiver and setting up fail safe, so when the signal is lost the engine goes to idle. I am sure this will generate allot of discussion. But I recommend Idle, so two things happen, you get some engine braking, and if the signal returns you have a running engine to control your plane with. As far as where you set control surfaces on fail safe is really a topic for discussion with as many opinions as you might imagine. My preference is the last signal received, but others will recommend many other variations. I am sure you will love your 330. I have a Radio Craft 330 with a DA 100. It is one of the best flying airplanes I have ever flown. Good luck with your new plane.