Fitting a 100ma RCD on Solar PV to solve nuisance tripping. | Page 3 | on ElectriciansForums

Discuss Fitting a 100ma RCD on Solar PV to solve nuisance tripping. in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

At page 12/20 para (iv) of:

https://www.----------------------------/mediafile/100117576/Best-Practice-Guide-3.pdf

(iv) Where a microgenerator having a d.c. source does not incorporate the equivalent of a transformer providing at least simple separation between the d.c. and a.c. sides, an RCD installed for fault protection by automatic disconnection of supply or for additional protection (I∆n <_ 30 mA) must be of a type that will operate as intended in the presence of d.c. components in the residual current. (This does not apply where it has been established – such as from a specific written statement given by the inverter manufacturer – that the inverter provides galvanic isolation between the d.c. and a.c. sides that prevents it from feeding d.c. current into the electrical installation.) Note. A Type AC RCD will not fulfil the above requirement. Depending on the level and form of d.c. components, an RCD (where required) will need to be of Type A to BS EN 61008 or BS EN 61009, Type B to IEC 62423, or Type F to IEC 62423. However, in the case of a PV power supply installation, Regulation 712.411.3.2.1.2 of BS 7671 stipulates that the RCD (where required) shall be of Type B.
 
At page 12/20 para (iv) of:

https://www.----------------------------/mediafile/100117576/Best-Practice-Guide-3.pdf

(iv) Where a microgenerator having a d.c. source does not incorporate the equivalent of a transformer providing at least simple separation between the d.c. and a.c. sides, an RCD installed for fault protection by automatic disconnection of supply or for additional protection (I∆n <_ 30 mA) must be of a type that will operate as intended in the presence of d.c. components in the residual current. (This does not apply where it has been established – such as from a specific written statement given by the inverter manufacturer – that the inverter provides galvanic isolation between the d.c. and a.c. sides that prevents it from feeding d.c. current into the electrical installation.) Note. A Type AC RCD will not fulfil the above requirement. Depending on the level and form of d.c. components, an RCD (where required) will need to be of Type A to BS EN 61008 or BS EN 61009, Type B to IEC 62423, or Type F to IEC 62423. However, in the case of a PV power supply installation, Regulation 712.411.3.2.1.2 of BS 7671 stipulates that the RCD (where required) shall be of Type B.
Yep, as I said.
 
Please provide an argument with reasons using your knowledge of electrical engineering, the wiring regulations, awareness of the law for the safe use of electricity and appreciation of the installation in question.
 
Please provide an argument with reasons using your knowledge of electrical engineering, the wiring regulations, awareness of the law for the safe use of electricity and appreciation of the installation in question.
I’ve asked you why the RCD can’t be removed.
All you’ve done is provided a link to a source which states that any RCD in the installation will have to be a B type.
Something that I am well aware of.
You have not given any reason as to why it can’t be removed.
Now (though you’ve not answered my question), you want me to explain in depth why an RCD is not required.
The simple fact of the matter, is that from the information provided, the RCD is unnecessary, it’s not required as far as BS7671 is concerned and at the moment it is causing a nuisance.

Now your suggestion, is to install an incorrect RCD to see if that will or will not also trip.
So if it trips, what then?
If it doesn’t trip, what then?
Who pays for the installation of this unnecessary and incorrect RCD?
Most of these inverters have inbuilt RCD protection and they also show error codes if there’s a fault.
Having an external RCD, is probably preventing the inverter from logging any fault.
 
Last edited by a moderator:
At last(!) someone who can provide an argument/reasons/instructions from the manufacturer why an external RCD is not required (-need to check this applies for type/make of OP's inverter) because there is circuitry within the inverter providing RCD functionality. For the particular wiring method an external RCD may also be required in which case it must have In of 100mA and be double pole.
 
Last edited:
At last(!) someone who can provide an argument/reasons/instructions from the manufacturer why an external RCD is not required (-need to check this applies for type/make of OP's inverter) because there is circuitry within the inverter providing RCD functionality. For the particular wiring method an external RCD may also be required in which case it must have In of 100mA and be double pole.
Strange that, because I did mention that most inverters have in built RCDs.
Of course you’d rather accept bone fide information from a manual that’s for a different inverter to the one being discussed in this thread.
Still it could be worse, could have connected another 30mA RCD in series and now be wondering why both are tripping.
 
The OP at #12 says the PV installation is on an isolated farm. This being the case is there not a requirement for an RCD with max In 300mA for fire protection; installed at the start of the sub-main to the PV's DB even though SWA is used for the cable run between the inverter and its DB?
For others to clarify.
 

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