Solar PV "Power failure"? Technicians in North East? Help!

Heedtheadvice

In my opinion if you mention a phase to earth fault tripping the mcb and the rcd has not tripped then the electrician could think you just do not know what you are talking about!

Whilst it is theoretically not impossible, it is most unlikely that a phase to earth fault will trip the mcb and not the rcd. The mcb is there to protect the wiring  should a fault occur I.e. in your case a sustained current being passed significantly more than 16Amps. This is to prevent the build up of heat in  the wiring, damaging the cable or (as above mentioned ) causing a fire. It should not be bypassed or attempts made to override it.

The rcd is specifically there to detect a fault current between either or both phase carrying wires ( live and neutral  in your case ). It is very sensitive and will operate very quickly ( thousandths of a second) for a fault current of thousandths of an Amp.

This post is just given as a guide  to help explain the main differences between an rcd and mcd and the protection thus provided ( leakage/shock for rcd and overcurrent/ short circuit for mcb). Do not take it as being all there us to it as it is a bit more complicated than the above!!

Telegraph_Sam

I will make no claims with regard to my level of technical expertise when the electrician comes. Such as the difference in function between the two devices as you have explained. Clearly the task is to identify the source of the tripping which appears to affect the mcb more often than the rcb. I just wonder if one can regard the solar pv inverter circuit as separate from the main house wiring circuit (lower voltage?) 

debitcardmayhem

For what it’s worth, I would have brought in a PV engineer rather than a general sparky. The fault may lie in the inverter

Telegraph_Sam

I may resort to that if the electrician can't sort it. Trouble is that PV engineers are a bit thin on the ground here

Telegraph_Sam

.Heedtheadvice said:

Whilst it is theoretically not impossible, it is most unlikely that a phase to earth fault will trip the mcb and not the rcd. The mcb is there to protect the wiring  should a fault occur I.e. in your case a sustained current being passed significantly more than 16Amps. This is to prevent the build up of heat in  the wiring, damaging the cable or (as above mentioned ) causing a fire. It should not be bypassed or attempts made to override it.

The rcd is specifically there to detect a fault current between either or both phase carrying wires ( live and neutral  in your case ). It is very sensitive and will operate very quickly ( thousandths of a second) for a fault current of thousandths of an Amp.

This post is just given as a guide  to help explain the main differences between an rcd and mcd and the protection thus provided ( leakage/shock for rcd and overcurrent/ short circuit for mcb). Do not take it as being all there us to it as it is a bit more complicated than the above!!

Whilst waiting for my electrician to make an appearance I am increasingly coming to the view that the above comment could be at the root of it. In the sense that the MCB tends to trip with the onset of strong daylight hours, but will begin to behave itself again when the strength of the daylight wanes. In which case my investment in a replacement RCB and MCB could turn out to be wrong. 

Main thing is to get it sorted.

QrizB

Telegraph_Sam said:

Main thing is to get it sorted.

When exactly is your electrician due to visit? What date have you agreed?

You've had this problem for more than a month and it could easily have cost you £300 already in lost FIT payments (based on a south facing 4kWp system near Newcastle, expected to generate 100kWh a week in July and August, and a 75p FIT).

chris_n

QrizB said:

Telegraph_Sam said:

Main thing is to get it sorted.

When exactly is your electrician due to visit? What date have you agreed?

You've had this problem for more than a month and it could easily have cost you £300 already in lost FIT payments (based on a south facing 4kWp system near Newcastle, expected to generate 100kWh a week in July and August, and a 75p FIT).

More like £400, that's what my slightly smaller system in the same area has made in the last month.

Telegraph_Sam

Looks like my electrician has done a vanishing act. I"ll need to find a replacement.
I doubt that I'm "losing'" anything like the £££'s you mention. Small consolation

Netexporter

If it is tripping out when it is sunny, I'd suggest monitoring your local voltage. If you see more than about 3 volts variance and the voltage rises to 253V or more, then it is very likely a high impedance fault in your local network. If you find that to be the case then ring your DNO, who will monitor your voltage, and make a repair, if necessary.

When I had a similar problem it was fixed in less than a week from my phone call and cost nothing.

Telegraph_Sam

I don't think the system knows what it is doing, the performance is not constant. I will obviously have to get it checked out by an electrician (endangered species).
How easy is it to measure the voltage, and how? Or I can just ring Northern Powergrid and get them to check - which may or may not resolve the tripping problem.