Where's the Earth ?

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michael8554

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My intention is to get the CU replaced in the New Year, so a change to a RCD Type S is academic, but will be added to the store of knowledge :->

So RCBO's throughout, and change the RCD to a 100 Amp Four Pole Mains Switch ?

Surge Protection for future EVSE ?

.
 

GEM Electrics

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fitting a 100mA s type brings back the exact same problem, if that trips everything goes off. so either youve just conned the customer out of a load of money doing unnecessary work and still not fixed the issue of 1 RCD on everything, or quite simply, there is no need for the 100mA time delay since any fault would be dealt with by the RCBO's making the upfront RCD redundant...
Hi Andy,
Yes, if the 100mA SType trips that is true, but the likelyhood of that happening becomes minimal* since most faults will occure beyond the RCBOs.
None the less you have a very good point. I suppose I am confusing the requirements of Ed15 on which I trained with the current regs. It is also notable that the OSG no longer has this in the diagrams (OSG Fig 2.1(iii)). None the less the OSG refers in para 2.2.6 to IET's wiring regulations which seems to require this... except the the note seems to excuse it..., (and contradicts 314.2). I have read the Note about 5 times and am still confused. I will try again after Christmas.
Geoff

* My experiance was that a carpenter had a faulty 110V transformer and regualrly (3 or 4 times a day) stopped the whole construction site working. Changing to the recomended wiring resolved this (only his circuit switched off).

michael8554 please note this - it may save money.​

 

steptoe

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As an aside to this,
Very very few widely available RCBOs in the UK are actually compliant as they are NOT DP , and are SP.
IMHO , SP RCBOs are no more compliant than dual split RCD boards are, and they are non compliant, but people simply turn a blind eye to this.
 

Fleeting

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No is no requirement in BS7671 for a protective device to switch the neutral conductor under fault conditions.
 
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No is no requirement in BS7671 for a protective device to switch the neutral conductor under fault conditions.
I think what @steptoe may be alluding to is the requirement , in certain situations, to 'isolate all current carrying conductors' and with the Neutral falling into this category the switching off of a SP device would not comply for example when working on a lighting circuit. I don't think he was posting in relation to circuit fault protection. But I feel sure, to be sure, to be sure, that he will shortly pop his head over the parapet with an erudite comment 😂😂
 

NMc

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Interesting

The supply is an old type of supply used in rural area with increase load demand. It is/was a 480v two phase supply - the heating load normally being split across the two 240v phases.

You say it was rewired 1970 ish well at this time the water pipe was sometimes using as the main earthing conductor. The meter is a 1992 so has been changed at some point. The RCD is not 1970 and looking at the circuit cables then additional circuits have been added at some point. Also solar panels

If I am correct then why have the earthing not been raised before?

First thing I would done is to pay for someone who understands this installation to fully inspect it and advise accordingly. I think you will have more than just the earth to worry about
 

michael8554

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You say it was rewired 1970 ish well at this time the water pipe was sometimes using as the main earthing conductor.
I've investigated further and I can see a 6mm green cable coming through the brickwork into the back of the house CU, maybe that goes to the bond I can see on the rising main in the kitchen.
If I am correct then why have the earthing not been raised before?
Why indeed ? No quibbles from the PV panel electrician, he just made a hole in the Wylex CU fuse cover to make room for a MCB.

The RCD was a replacement at least 5 years ago for a much older 30mA Wylex RCD, by an electrician called in to investigate nuisance tripping. He told me that the trip threshold had become low on the old RCD. I now understand the more likely cause, that the earth leakage of all my wiring and appliances sometimes goes over 30mA, a previous toaster would sometimes cause a trip.

All will become apparent when the CU is updated !
 

septiclecky

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My intention is to get the CU replaced in the New Year, so a change to a RCD Type S is academic, but will be added to the store of knowledge :->

So RCBO's throughout, and change the RCD to a 100 Amp Four Pole Mains Switch ?

Surge Protection for future EVSE ?

.
I would get the whole lot replaced and tidied up, it looks a right mess
 

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