Actually a motor
or an alternator if brushed can create static electricity.
We have just gone through an issue with electric fuel
pumps, apparently the dust and brushes
were generating a high static charge that was being discharged through the brush block and damaging the armature, the fix seems to have been both grounding the motor
with a ground wire and the motor housing being cad plated as opposed to being painted, cadmium conducts electricity, paint
I would ground the thing if you suspect it's building static, yes I now it is already grounded, but the case may not be well grounded, and an additional ground wire can't hurt anyway.
I think it unlikely, but then I didn't believe that was the problem with the fuel pump