It would also depend on how the RFC is wired, they should be wired im such a way that the current is balanaced down each leg to each point of use. Alot of people will pull a cable to the nearest point and then futhest point then just link them along the way which can cause it too happen also.
Agree with Tel, pay now to have everything done and it will be good for another 20+ years if you ensure any future alterations are carried out by a competant electrician.
Sounds like I am in the minority here, but I would say go for it as long as you can afford it (meaning having plenty of money to cove your outgoings for a fee months). You only get one chance and you may regret it in the future. If it goes wrong there will be opportunities in the future for full...
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