Answer:
Deny the motion, because the electrician is not a necessary party.
Step-by-step explanation:
A necessary party is defined as a party that is required to be joined as part of a case and without who a case cannot be decided.
The party must be indispensable in the ruling to be considered as being required to be joined.
However in this scenario either electrician or the gas worker can be held entirely responsible for the fire. So the case can be satisfactorily decided without joining the electrician.
The home owner can raise a seperate case against the electrician if he so feels in the future.