Originally Posted by A Salt Weapon
That's what I was taught too, however I was flipping through one of my vendors catalogs the other day and it had a reference to that being a myth started by the igniter companies to keep techs from touching them.
I don't believe it is a myth for a couple of reasons. A lot of times the ceramic ignitors are in a tougher position to replace than spark/electronic ignitors since they have to be in line with the gas flow into the exchanger. If you could touch them and get away with it your time to do the change would be half. During some of the training that I received from Carrier there was a video where they showed 2 ceramic ignitors next to each other in the same frame. The narrator touched one and of course not the other. You could easily see the darker spots in the glowing area of the ceramic where the one was touched. It lasted for less than 200 cycles. They are suppose to last for more than 200,000 cycles. I was convinced to say the least.