DIY'ers and Earth wires.

[Engineer54]

Metal containment systems have been extensively used for far more years than i've been around. It has long proved itself as providing both sound mechanical protection and as a sound electrical earthing (cpc). No such thing as a spindly metal conduit system!!

I can show a multi factory site built from the 50's, with extensive metal containment systems that have Zs values that even to this day, don't come even close to max values... If that's not deemed as being reliable then i don't know what is!!

The problem with metal containment is that these days far too many electricians don't have any experience of installing it, they are far more likely to be seen hacking and butchering it to enable them to run T&E or SWA or the like!!

Every major project that i've been involved with, metal containment has been the predominant means of electrical installation without a single separate CPC conductor in sight!! All our metal containment systems are subjected to high current (25A) ohm meters sectional tests, and believe me you can't hide any weak connections with those things. Metal containment systems erected/installed and tested by experienced operatives will last for decades. As a system it's second to None, and ill stand by that statement till the day i die!!

 

[Bobster]

Nothing like hearing a poor joint crackle under test!

 

[Engineer54]

Small point, but when using a separate conductor in metal conduit for the cpc, how do you test it for continuity?

Wander lead!!

 

[Engineer54]

Nothing like hearing a poor joint crackle under test!

Exactly ...lol!!

 

[andyb]

Wander lead!!

But you will be getting a reading through the containment.
If the cpc is broken in several places you would still get continuity.

 

[Engineer54]

The containment is the CPC, if the containment is broken you won't get a reading past the break...

 

[andyb]

The containment is the CPC, if the containment is broken you won't get a reading past the break...

Misunderstanding E54, my post was referring to testing a separate cpc not the containment.

 

[Engineer54]

Misunderstanding E54, my post was referring to testing a separate cpc not the containment.

That's the point, there is no need for any separate CPC's in a metal containment system

 

[andyb]

That's the point, there is no need for any separate CPC's in a metal containment system

I know, that's the point I was trying to make.

 

[Guest77]

Ime sure most of you see this on a day to day basis but as I dont do house bashing this still annoys and baffles me....

What is it with DIY'ers and the general lack of care when it comes to earth wires?

Went to change one of my lights this evening, Changed a few sockets and switches but not needed to do a light until now. Thus far everything I have worked on has been fine.

So I take the old light down which I thought would of been changed by the previous owner due to its odd fit in the room and sure enough I pull out 3 T&E's all twisted together and wired into choc blocks except of course the earths which for some unknown reason the individual thought ok to twist together and wrap in tape.
No choc block, No crimp, No Wago not even a dab of solder - NOTHING!

WHY!!???

What is it with people that think the wire thats there for safety doesnt matter?

I have seen it a few times in various houses I have worked in but it still suprises me and generally gets on my wick.

Needless to say its now been done properly and I think I may have to check a few other things.....

Good question fella, I have no idea why they do that either, insulation tape is the best friend of a DIYer, at least they were joined together, I have seen them cut out before :biggrin:

 

[Tiny Spark]

Blimey looks like this had opened a unforeseen can of worms lol

As for my light fitting its now blinding the Ms when shes doing tea.
No further abortions were found and everything looks original and all earth wires present and correct!

Why in hells name they felt the need to fit a single spot (study type) in a kitchen I do not know!!

Me personally i always run a separate CPC unless we are talking large armoured cables etc where it is not cost effective.
Reason being I have seen way to many badly maintained trunking runs etc where joints have been stollen or butchered to accommodate something at a later date.

As a slight off shoot I remember some years ago fitting a ceiling fan light in for a friend.
I was rather stumped when I pulled all the wires through the ceiling to discover they had been twisted together and wrapped in some kind of black tape that I can only describe as Tar-y.
A old boy I spoke to about it reckons it may of been the stuff that they used to use to wrap around gas pipes many moons ago.
Whatever it was though it took me longer to slice off each layer with my stanley than it did to do the entire job!!