What readings should I expect?

[Ookysoft]

CONTINUING SAGA....

Started looking at the electrics of this house I'm remodeling -

Seem to have 249v Live Neutral
Seem to have 178v Live to Earth

Kinda thought I should have higher voltage to Earth?

TT system - not convinced it's earthed properly

New looking earth cable wanders across the house and down the back but can't track it beyond the back wall as yet. It may lead out to a shed or down to earth there somwhere.

Old earth cable had been cut 1/2 way down the outside wall where an earthing rod in in the ground.

Kinda think, if a sparky popped a new earthing system in, he'd have at least disconnected the old from the Wylex fusebox & not just cut it away up the outside wall.... Previous home owner did do odd stuff with electrics so if it kept popping the ELCB I wouldn't put it past them to just clip the E. [ Test buttin on ELCB does squat ]

Wondering if I should just double-up to be sure & reconnect the old earth [ new and thicker wire ]... assuming I can find a suitable clamp for the old stake.

Untitled

• Ookysoft
• 9 Mar 2010
• 2

 

[ban-all-sheds]

Wondering if I should just double-up to be sure & reconnect the old earth

No, you should get rid of that old voltage operated ELCB, you should get rid of all the old cables, you should get rid of all the old connector blocks, you should get rid of the socket in the bathroom, you should get rid of the Wylex rewirable fusebox, you should ask the DNO about a TN-C-S supply, and you should rewire the whole place.

 

[securespark]

YIKES!

That's a killer....

IF you have a TT supply with an effective Ze of >200 Ohms, with a VOELCB that does not even work, then you have a highly dangerous situation.

You need to get a decent connection to earth. A good quality rod into dense damp soil (not dry rocky ground), plus 30mA RCD protection.

Just temporarily, until you're sorted for good, get the rod sorted and put a 30mA RCD on the tails to give protection to all circuits. What about that other CU on the right? Is that in circuit?

The other thing to consider to make you safe is the PEB's to water, gas or oil.

 

[plugwash]

Wondering if I should just double-up to be sure & reconnect the old earth [ new and thicker wire ]... assuming I can find a suitable clamp for the old stake.

Maybe as a temporary measure but you REALLY need to get this inspected and tested by an electrican with PROPER test equipment (it is NOT possible to test a rod with just a multimeter) and get that old voltage operated ELCB and equally old consumer unit replaced with something that complies with modern regulations.

It will require further investigation to determine if a full rewire is actually needed but it may be a good idea to do one anyway if you belive the previous occupant was a bodger, otherwise it's very difficult to be sure you got rid of every last bodge.

 

[SparkyNinja]

Are you an electrician Ookysoft?
Do you have much experience with electrics?


Its sounds like it could have possibly been a reposition of electrode in an attempt to gain a better reading.
You may want to consider getting a test done to it? BS7671 now gives us a figure of acceptance of up to 200 ohms.

Test buttin on ELCB does squat

The ELCB should be replaced, especially as you mention that the test button does not work.

 

[ban-all-sheds]

Are you an electrician Ookysoft?

I will have to get a sparky in to check out the whole lot

 

[SparkyNinja]

Are you an electrician Ookysoft?

I will have to get a sparky in to check out the whole lot

My apologies BAS, I will ask in another way.


Ookysoft, how much experience with electrical installations do you have?







oh I already said that.

 

[ban-all-sheds]

My apologies BAS, I will ask in another way.

I wasn't having a dig at you - just didn't think you'd seen his other post....

 

[Ookysoft]

Yes, yes... deffo have to strip it all out - I've started in the loft now - there are wires running in all directions from the previous rewiring & older wires still up there - taking some time to identify what cables NOT involved with upstairs lighting is doing there.

While I'm in the loft - practice on 2 way switching... take live/neutral from upstairs or downstairs ring? Which ever, I know BOTH live and neutral to be from the same ring - came across a 'borrowed' neutral once.

Done loads of wiring before, though admittedly not on this scale - got thrown across a room as a kid so learned early on not to assume anything and to work carefully.

Did a Part P defined as a part of 1 of these dodgy plumbing courses - total waste of time - a farce actually "Have you ever wired up a central heating control system? You have? We'll sign that off as done then!!"

Though I do consider myself to be competent, I prefer to double check, ask possibly simple things and not rush.

I was expecting the PD between Live and Earth to be the same as the Live/Neutral [ or within spit]. I appreciate that to measure the resistance of the earthing system is what I should be doing here - slight skills shortage on that one. Theory is trying to tell me that I'm measuring between Neutral and the earth [ disconnected from the CU ] as that's the only measurable circuit which connects the Earth?

The board on the right is a consumer unit for night storage heaters - 100A 30ms breaker if I remember. All that's coming out which will remove loads of underfloor spaghetti.

Earth to water pipe was not connected and right now there's 1 only a basin plumbed in so not really an issue - will add bonding where appropriate when the pipework goes back, however most will probably be plastic. That's another possible breakdown in earthing actually, it's copper going underground... no idea when that was cut but its old as no sheathing - assuming that the narrow stuff [now cut] going out the wall to the rod replaced it on the re-wire....

Yes, I will persuade the client to check with the Supply board with regards to TN-C-S.

 

[ban-all-sheds]

take live/neutral from upstairs or downstairs ring? Which ever, I know BOTH live and neutral to be from the same ring

Wouldn't a lighting circuit make more sense?

Though I do consider myself to be competent,

Competent to design and carry out a complete house rewire, to test it, and issue a certificate saying that it fully complies with BS 7671:2008?

slight skills shortage on that one.

Unacceptable. Your client has every right to expect to get someone without a skills shortage.

Yes, I will persuade the client to check with the Supply board with regards to TN-C-S.

No - advise the client to ask his electrician to contact the DNO.

 

[Ookysoft]

Yes, I did mean lighting ring.

No I can't issue certification - but that's why I'm to leave everything I'm doing exposed for the Building Controls inspections.

 

[Monkeh]

Yes, I did mean lighting ring.

Lighting circuits are not wired in rings. If you don't know this, you really should not be doing electrical work. Especially not for money.

 

[SparkyNinja]

I would advise that, on projects of this size, you contact a local electrician who may be able to give you some guidance.

Even if you want to carry out the work yourself, it will probably save you time and money to pay for a couple of hours of an electricians time than it will for you to come to places like this for information and direction.

 

[riveralt]

Did a Part P defined as a part of 1 of these dodgy plumbing courses - total waste of time - a farce actually "Have you ever wired up a central heating control system? You have? We'll sign that off as done then!!"

Though I do consider myself to be competent, I prefer to double check, ask possibly simple things and not rush.

Sounds as if you are doing a full rewire here.

Are you registered with a competent persons scheme to sign your own work off? Or are you competent enough to demonstrate to the Local Authority Building Control that you can design, install and inspect to BS7671.

If not you or your client need to contact your LABC and inform them of the work you are doing under Part P of the Building Regulations.

Competent to design and carry out a complete house rewire, to test it, and issue a certificate saying that it fully complies with BS 7671:2008?

BAS does this mean you are coming round to the fact that BS7671 (2008) is the defactor standard for Part P?

 

[Ookysoft]

Yes, I did mean lighting ring.

Lighting circuits are not wired in rings. If you don't know this, you really should not be doing electrical work. Especially not for money.

In this house, they are rings. In my parent's house they are rings.