No need. Just make a circuitry piece, and then type in console '!set type metl tesc'. That way tesc will not produce lightning, and since you can't destroy it, you should be fine.
And if you just want it to be a yellow iron/metl, heres my opinion: Click here!
There's deco layer for some reason..
tpt.eltransition.metl.tempHighValue = 10001
If you set its type to tesc it won't melt or give lightning away..
OR, you can make a circuitry with tesc and set its tmp to 0.
Woah, nice find, of set type thingy.