Fitting a 100ma RCD on Solar PV to solve nuisance tripping.

[Deleted member 26818]

Where is the RCD, what is it protecting?

 

[westward10]

He refers to it as the 30ma main switch in #1.

 

[Deleted member 26818]

Where is the RCD, what is it protecting?

He refers to it as the 30ma main switch in #1.

Thanks.

 

[South Spark]

Where is the RCD, what is it protecting?

Thanks.

Just the circuit to the inverter. Which is on its own 2 way consumer unit.

 

[westward10]

I could be wrong but isn't 100ma the minimum recommended assuming it is not required for additional protection.

 

[Octopus]

Just the circuit to the inverter. Which is on its own 2 way consumer unit.

And then SWA cable - so no rcd required imho

 

[marconi]

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

See page 12/20 Para (iv) for advice on RCD protection .

 

[marconi]

From my research it seems many Sunny Boy inverters are transformerless which means that there is usually no galvanic isolation between the PV dc input and ac output. If you tell me the model number of the inverter I will delve further.

I thought of an experiment you could do which might determine whether the leakage current waveform is ac or dc. At the moment the RCD is type B which can detect the waveforms ac 50Hz, ac 50Hz pulsed, Smooth dc, and ac greater than 50Hz into kHz region - see page 7/21 of:

http://www.doepke.co.uk/download/Techpub-16

The type AC RCD commonly used in Consumer Units can only detect ac 50Hz - it is blind to ac 50Hz pulsed, Smooth dc, and ac greater than 50Hz into kHz region.

What you could try then is inserting a type AC 30mA RCD upstream of the current type B and then observing what happens every morning to the type AC one -does it or does it not trip?

Just an idea for your consideration which might cast a bit more light on the problem by giving information on the waveform of the leakage current (as well as my # 15).

 

[netblindpaul]

Don’t forget that a type AC RCD may simply be blinded by DC such that it will not operate at all, as in will not sense AC or, DC leakage.

 

[marconi]

Re #24: What you could try then is inserting a type AC 30mA RCD upstream of the current type B and then observing what happens every morning to the type AC one -does it or does it not trip?

I am not suggesting removing the Type B.

 

[Deleted member 26818]

What would be wrong with removing the RCD altogether?

 

[marconi]

Re# 26 - see #22

 

[Deleted member 26818]

Re# 26 - see #22

Been there, done that.
What would be wrong with removing the RCD altogether?

 

[marconi]

Answer yourself - I will be interested to read your reasoning.

I have provided a reference which explains why it is right an RCD type B is intalled because there is no dc - ac side galvanic isolation. It may well be the manufacturer of the in-use Sunny Boy inverter says one is not required - one for the OP to clarify - though for me the presence of the type B RCD indicates that the installer has read and abided by the manufacturer's instructions.

 

[Deleted member 26818]

Answer yourself - I will be interested to read your reasoning.

I have provided a reference which explains why it is right an RCD type B is intalled because there is no dc - ac side galvanic isolation. It may well be the manufacturer of the in-use Sunny Boy inverter says one is not required - one for the OP to clarify - though for me the presence of the type B RCD indicates that the installer has read and abided by the manufacturer's instructions.

The reference you have provided indicates that where required, B type RCDs should be used. i.e. circuits of locations containing baths or showers, socket-outlets or cables concealed in walls.
There is nothing there stating that the supply to or the output from the inverter requires RCD protection.
The OP says that the RCD protects the circuit to the inverter and that the circuit is wired in SWA.