Hi,
My daughter lives many miles from me so I am working off what she has communicated to me.
She has a small house (ex local authority) that has a Crabtree 7x way consumer unit. Over the past couple of days the RCCB has tripped a few times. Non of the individual circuit breakers have tripped. The CU has separate contact breakers for the socket ringmain, a separate socket ring for the kitchen, a cooker circuit and a circuit breaker covering the lights. All circuits are covered by the one RCCB.
Would she be better be best to employ an electrician to just to fault find the RCCB tripping or go for a CU replacement (where I assume any electrical faults will be dealt with as part of the work) - and incorporate RCBO's so each circuit is protected separately. The CU looks okay to me as a lay person from the picture she sent but certainly not new, but I know looks mean nothing without testing. The cables are plastic insulated (black and red insulation on conductors with grey outer insulation). I guess what I am really asking is: does she pay for the RCCB fault to be diagnosed and repaired, with a fair chance that the CU is coming to the end of its life … or ' cut to the chase' and get the CU upgraded which would hopefully eliminate/ identify which applicance (if it an appliance that is creating the current imbalance at the RCCB). You will understand from reading the above that I know very little about domestic electrics. However, as a father it is me who my daughter will be expecting to come up with the way she should proceed. Many thanks in anticipation of a response.
Are you a tradesperson and able to answer this question?
If the RCCB has been tripping then you have an Earth to neutral or earth to live fault or, less likely is a faulty RCCB. Circuit breakers only trip out on overload and are there to protect the cable of the relevant circuit. Several ways you could go with this, definitely get a registered electrician in to do an EICR on the premises, this way everything gets tested out, surveyed, ie presence and size of main bonding conductors it will either be satisfactory or Non satisfactory. Dependant on the results, you can then either stay as you are with all the remedial work done, or go for a dual RCD board-cheaper or RCBO’s these are less hassle but expensive. Just remember if you have the board changed you require an Electrical Installation Certificate when complete and notified to Building Control. With the EICR you also require a certificate.
Employ an electrician to rectify the fault. You gain nothing from upgrading the consumer unit as the new unit will offer the same protection. Any competent electrician would in 99% of cases be able to locate or narrow down the fault to a specific circuit or piece of equipment in less than hour. Save your money.
MCBs (fuses) protect equipment by tripping if the circuit is overloaded for a significant time eg plugging in too much into the sockets. RCBs protect people by tripping instantly if there is danger of electric shock. It is probably an earth fault somewhere. I suggest getting an electrician to take a look. The earth fault won't be fixed by changing to a new CU. It needs to be traced.
The wiring sounds old. Old wiring colours + likely to be old if each wire has separate grey coating. You don't mention earth wires (green or yellow/green). Old houses don't always have earth. Ask what he recommends upgrading.
It's entirely up to you if you need to medernise the CU. If you do, our advise is to select metal CU with dual RCDs because having CU with RCBOs is very expensive. The only advantage is that if there is a fault in a specific circuit it will trip without tripping other circuits.
If you go with fault finding option without modernising the CU, here are some steps we usually advise our customers to follow prior to scheduling a fault finding appointment:
1) Remove plugs from all sockets
2) Switch off all appliances/under cabinet lighting from the double pole wall switches (if any)
3) Turn OFF all circuit breakers
4) Turn ON the RCCB
If turned ON without tripping go to the next step. If trips, go to step6
5) Turn ON circuit breakers one by one.
If no circuit breaker trips go to step7
If you identified which circuit caused the trip go to the next step.
6) Contact an electrician. Jump to step9
7) No fault on the CU or wall sockets
8) Try to put on all plugs & turn ON and switch ON all appliances or under cabinet lighting. See which one caused the fault and replace it with new one.
9) End
