My fathers house has an old wiring system and there is no grounding wire. The plugs are all 2 prong and becuase of this the insurance company has demanded to have this upgraded or premiums will rise. my question is this....for an old house how does one estimate the cost of the job? Its plaster and lath and likely it will be difficult to fish new wire. Myself i have no idea what the cost could be. Thanks in advance.