I don't know. I never kept track. Mary said it was dozens. I recall fewer than 20 but Mary was a beancounter who kept track of things.
Could also add a 220 to 110 xfmr or autoxfmr.
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electronic ignitors deliver about 30 watts to the electrodes so I'd think a 50 VA xfmr would suffice nicely. Just find a 50 VA xfmr with two 110-volt primaries, connect them in series, power the whole series primary and take 110 off of only one primary. The one I cited is 80 VA. The electronic ignitor's HV side is xfmr isolated from the primary circuit so the secondary center-tap ground customary and maybe code in oil ignitors would still be OK.
I'd just add a neutral.