2 RCD's on circuit

[kayloh]

I had to remove my post as it was a bit sarcastic. But why are you (the OP) getting involved in this when you don't seem to know what you are doing? I mean no disrespect, it's an honest question.

Like I said in a previous post, it's practice... I'm more specialised in part rewires / new rewires... never did much fault finding but this seems like a good opportunity to try... client is a long term friend so nobody loses anything since I'm doing it as a favour... it's why I want different opinions on what it could be to test out each one... I'm not here to play who's the better sparkie... I just want some guidance...

 

[Andy78]

Like I said in a previous post, it's practice... I'm more specialised in part rewires / new rewires... never did much fault finding but this seems like a good opportunity to try... client is a long term friend so nobody loses anything since I'm doing it as a favour... it's why I want different opinions on what it could be to test out each one... I'm not here to play who's the better sparkie... I just want some guidance...

Guidance:
Research RCDs, their function, and their associated testing.
Visit the property and commence fault finding in a logical manner starting with a chat with the customer about common usage patterns and appliances, and progressing to inspecting and testing the circuit.

 

[Lucien Nunes]

In the meantime, draw schematics of various possible fault conditions arising on RCD-protected circuits, calculate applicable resistances required to cause a trip (minimum can be taken as 15mA IΔN) and consider especially the reported symptom that larger loads tend to cause tripping.

 

[hightower]

Not being funny OP, but a lot of this should be very basic, fundamental knowledge, to anyone with a 2357 under their belt.

 

[kayloh]

Not being funny OP, but a lot of this should be very basic, fundamental knowledge, to anyone with a 2357 under their belt.

Mhmm most courses tend to teach about health and safety and cable calcs... lessons on fault finding and installation side tend to be broad and quick since the curriculum is more lenient towards theory (least in my college)... personally I haven't been taught how to fault find properly so it's just been picking up knowledge on the way, and your statement about having a 2357 means nothing since I know a lot students who have the same qualification and yet have no idea how to do a simple ring circuit let alone a radial... it's all about experience, which is what I'm trying to do...

 

[westward10]

It is all very well having qualifications done from a whiteboard and test rigs, unfortunately this doesn't always transfer to the real world. What is basic and fundamental to some is not necessarily the case for others. The real world is where we gain experience, we have all been there.

 

[rolyberkin]

Is @hightower says a C&G 2357 is not just about new fits it has a test and inspection element and also fault finding, judging by your previous posts I suspect you have gone through a very quick course and may be in well above your head. If you really don't know the answers to your questions you really should not be undertaking work for people and should get yourself on an apprenticeship or some on the job experience with an experienced electrician!

 

[buzzlightyear]

she uses the shed as a massage parlour,
has the shed got any lighting on that 32amp mcb/rcd ?

 

[hightower]

Isn't 2357 an apprenticeship, that should have been completed on the job?

 

[Leesparkykent]

Isn't 2357 an apprenticeship, that should have been completed on the job?

Might of done the 2356 level 2&3 then the bridging unit, portfolio and AM2.

 

[joebell25]

Before removing the RCD in the shed, you may want to first ensure that the earthing system hasn't been changed to a TT system for the shed consumer unit.

 

[HandySparks]

Before removing the RCD in the shed, you may want to first ensure that the earthing system hasn't been changed to a TT system for the shed consumer unit.

The OP says that there's a 30mA RCD in the board supplying the shed. This would still provide protection even if the shed earthing is TT.

 

[Octopus]

The OP says that there's a 30mA RCD in the board supplying the shed. This would still provide protection even if the shed earthing is TT.

I was pondering about this advice .... I've seen it locally too where a DIYer assured me that TT'ing a shed would stop the shed circuit tripping his up front single RCD..

 

[Wilko]

I was pondering about this advice .... I've seen it locally too where a DIYer assured me that TT'ing a shed would stop the shed circuit tripping his up front single RCD..

Any electrons escaping down the shed's rod will inbalance the L/N feed all the way back, I'd have thought.

 

[hightower]

Is that a point open to debate though - if you TT an outbuilding should you have it's own RCD in there too (even if the upfront one will protect)? Or would you say it's perfectly acceptable to have an RCD at the CU, TT the outbuilding, and not install a second RCD at the outbuilding.