An Interesting CPC connecting method... With a damp problem!

During a periodic inspection today come to testing a ring,  L & N loop reading 0.56 & 0.57ohms... Thinking looking reasonable..

Then measure CPC..  readings bouncing around between 1000.0ohms and 1200.0 ohms.!!!!

Mmmm, thinks bit of a dodgy joint problem somewhere here..

Ask customer if any recent work....

Reply comes: Not since they moved in a few years ago, but the kitchen had been redone not long before they moved in..

I am thinking could be a Kitchen fitter created problem..  But NO..  I was proved wrong...

With all conductors disconnected at board, I wago together L-N-E at one end of ring.

With my 13A plug to meter lead adaptor I go round measuring 'L'->'N'  and 'L'->'E', continuities at every socket I can find....

From the L->N readings I can suss out the socket wiring order..

and the L->E readings have some sockets less than 0.22 ohms and all the rest greater than 250.0ohms..

From the established socket order notes I had made, I open up the last of the low L-E reading and the first of the high L-E readings....

And low, it was beholdent unto me, that one of the old original sockets in the dining room...  (Outside wall)...

Has mucho dampness issues AND, an interesting method of wiring CPCs...



Please NOTE:-

(Left Hand Cable) CPC onto socket E termination,

(Right Hand Cable) CPC onto metal back box lug.  Also with a twisted joint if you look close.

So CPC continuity is via the socket to back box "corroded" fixing screws....

Me thinks the kitchen fitters should have noticed this whilst amending this same circuit in the kitchen??! :shakehead  

As I am guessing this has been corroding for a few years now?

P.S.

Did a fix got my ring continuities back to:-  L&N at 0.56ohms    CPC at 0.91ohms

Guinness

Reminds me of an EICR I carried out only a couple of weeks ago....... every socket had the earths terminated in the back box only... totally reliant on the accessory screws (no rust though)

Just to add the homeowner was out at work...

BUT his dad was there while I was doing my testing...

and he was quite shocked by the condition of the socket...

It emphasised to him the headache with the old chestnut of.....

"It was working for years, long before you looked at it so it must be OK?"

Just out of curiosity is it in a Bungalow at all? Both times I've seen back boxes like that it's been damp in Bungalows. One being my brother new purchase a few years ago. Wallpaper peeling off and mould. When he converted the upstairs and put a proper boiler in damp went. Plus I think both properties weren't caity walled.

The second prpery was so damp the RCD was popping.

I came across earths only to the back box during a recent EICR. So not an isolated case.

It is also surprising how often I find dripping wet or corroded sockets, it continues to shock me just how utterly carp a large amount of the UK housing stock is.

Rutts35 said:

Just out of curiosity is it in a Bungalow at all? Both times I've seen back boxes like that it's been damp in Bungalows. One being my brother new purchase a few years ago. Wallpaper peeling off and mould. When he converted the upstairs and put a proper boiler in damp went. Plus I think both properties weren't caity walled.

The second prpery was so damp the RCD was popping.

Click to expand...

It was an old end-of-terrace property. This socket is on the far end gable wall of the row of properties..

very much doubt if there was any cavity..

At some point in the past The wall had been dot & dabbed over with plaster board...

I am guessing to overcome previous damp issues....  :shakehead

I would think in years gone bye they were some of the old industrial terrace properties...

No frontage, just front door straight out onto the pavement....

However now a wide pavement sufficient to park a car off the road.. (but block 80% of the pavement!)...

If I said it was a Black-Country terrace house somewhere between Dudley & Netherton..   

Young Deke with know exactly the type of residence I mean.   

Unfortunately, with so many of the stupid house prices nowadays, these types of property appear to be one of the few avenues that young first-time-buyers can stand any chance of getting around here!   headbang

Guinness

ProDave said:

I came across earths only to the back box during a recent EICR. So not an isolated case.

It is also surprising how often I find dripping wet or corroded sockets, it continues to shock me just how utterly carp a large amount of the UK housing stock is.

Click to expand...

I think there are four types of property....

1/ Really old, no cavity walls, made of brick, mortar, timbers with big nails etc..   damn-near impossible to insulate to any reasonable standard without spending greater than the value of the property!

2/ Really new,  with insulation stuffed into every orifice that is not a door or window... But made out of Polystyrene, plasterboard, chipboard, with no-more-nails and frame or silicone sealant..   Walls so thin you can hear the neighbours phone ringing on their bedside table, from your lounge....

3/ Good down to earth, proper construction and insulated properties that are now way out of budget for the average earner, with two incomes and one or more kids to support..

4/ Custom designed and verified.  built using the savings and cash obtained by selling a previous property 10 years ago, investing some of it into a nice little earning pension -pot and the rest on buying a plot of land at auction ready to build on!

Guinness

Or something like that...…?

There are an awful lot somewhere between your categories, built through the first half of the  20thC. These have sound all brick cavity walls and heavy woodwork but with little concept of insulation. My family house for 40+ years was such a one, built late 1920s with Accrington brick walls.

The main flaw with mine was poor damp course material, like cheap roofing felt, and a common brick inner leaf all too ready to soak up water.  These are the ones targeted by the cavity insulation injection companies. something I wouldn't touch with a barge pole! 

Up here there are LOTS of old stone cottages and the standard interior fit out is to make a frame and board it inside, even going back to lath and plaster days so nothing new ("plaster on the hard" was considered what only poor people did) . But there is rarely any insulation and it is usually open to the loft space, so on a windy day if you remove a switch or a socket a howling icy gale comes out of the hole.

The "stock" 1960's / 70's ex council houses almost all have damp and condensation on the walls somewhere.

To your list add 5)  Self built modern low energy house where the owner has spent a great deal of effort detailing the insulation and air tightness and has achieved a truly low energy house.   There won't be all that many in this category yet.  Our new house is very quiet indeed, all that insulation makes the house very sound proof as well as warm.  And we are about 30 metres from the nearest neighbour so won't be troubled by his noise.