For the sake of the OP and not wanting to get too technical, my understanding is that a consumer unit change would require a full test at the end anyway and even though the existing wiring my be safe and conforming to the standard to which it was installed, the CU change will require it all to conform to the current standards. The electrician is probably quite sensibly suggesting the test at the beginning to identify any potential problems up front. As suggested a PIR will identify how the installation performs to current standards and would allow the OP to make informed choices about the upgrade and cost of the installation.
I'll give you a nice mk sentry dual rcd consumer unit to replace your old wylex... Problem is once I've changed the fuse box I become responsible for the safety of the circuits.
I charge around £300 for a consumer unit upgrade (house up to 30 years of age) plus the cost of any bonding upgrades required. I can get a dual rcd 10-way mk sentry for a little over £100 at the moment with mcb's. This leaves potential gross profit of nearly £200 for a day's work. Most jobs are normally straight-forward - it's when a DIY fanatic has been let loose or rouge builders where problems can begin...
Anyway, the jobs where issues arise I am unable to upgrade the fuse board without first having resolved any issues - would you agree?
Any house with electrics over 30 years need an in-depth PIR done - a 3-bedroom property at around £160 for a professional test and inspection. 6 to 8 hours work - not the maximum 4 hour social housing job. (I could never work out how the social housing providers never cottoned on to the same name being on 4 PIR's a day when the PIR's were undertaken by private contractors).
So... If i am unable to change a fuse box because, say, no end-to-end resistance is on the ring circuit, I'll plug a cable into the circuit under test to locate the rough area of break in the circuit... It could be just a couple of loose wires in a back box, hence include an hour or 2 remedial works with a consumer unit upgrade, BUT!
If the issues are more extensive I am not going to change the fuse box and a £100 for 4 hours work is better than having to say "I can't leave your kitchen circuit on coz the cables have an insulation resistance reading of .2 MegaOhm as well as no Live-Live continuity... hence your kitchen circuit is not a ring, but a radial and should be protected by 2 x 15/16 amp fuses/mcb's. I'm not going to say "I can't do a certificate unless you pay me X-hundreds to put it right" either.
I simply want to provide a report, charge £100 (deductible from original £300 consumer unit upgrade charge when eventually done) and leave the customers to decide what is to be done - we all have budgets to consider.
