Earth Fault, Loop Test Reading >200ohms


Postby The Renovator » Fri Jun 15, 2007 6:05 pm

Hi,

I'm new to this forum and not an expert by any means.

Scottish Gas came to do a service on my boiler today but wouldn't go near it because their electrical test revealed an "Earth Fault, Loop Test Reading >200ohms".

I spoke to the engineer on the telephone (as I wasn't there when they visited) and he told me the reading was "around 200ohms" but should be below 1ohms.

My question is - should I be switching off my mains switch and continuing this post on battery power until I get an electrician in or should I be okay to wait until he arrives in a few days?

The Scottish Gas engineer did tests on several plug sockets in my house (upstairs and down) and found similar readings through out. I don't have a clue why this would be, nor do I understand why it seems to be consistent throughout the house (what with all the circuits being on different loops).

Can anyone explain the technicalities too? e.g. if there is a fault on one circuit, should I expect it to affect the entire supply?


Thanks in advance,

The Renovator
The Renovator
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Postby BLAKEY1963 » Sat Jun 16, 2007 12:19 am

[quote="The Renovator"]Hi,

I'm new to this forum and not an expert by any means.

Scottish Gas came to do a service on my boiler today but wouldn't go near it because their electrical test revealed an "Earth Fault, Loop Test Reading >200ohms".

I spoke to the engineer on the telephone (as I wasn't there when they visited) and he told me the reading was "around 200ohms" but should be below 1ohms.

My question is - should I be switching off my mains switch and continuing this post on battery power until I get an electrician in or should I be okay to wait until he arrives in a few days?

The Scottish Gas engineer did tests on several plug sockets in my house (upstairs and down) and found similar readings through out. I don't have a clue why this would be, nor do I understand why it seems to be consistent throughout the house (what with all the circuits being on different loops).

Can anyone explain the technicalities too? e.g. if there is a fault on one circuit, should I expect it to affect the entire supply?


Thanks in advance,

The Renovator[/quote]



THE RENOVATOR
ARE WE ASSUMING THAT SCOTTISH GAS
PERFORMED AN EARTH LOOP IMPEADANCE TEST AND GOT A READING
OF 200 OMHS +.
OK THEN IF WE ARE , THEY THEN STATED THAT THE READINGS SHOULD BE BELOW 1 OMH , IT IS POSSIBLE YOU COULD HAVE A PROBLEM WITH EARTHING.
IF YOUR SUPPLY TO YOUR HOUSE IS A T.N.S OR T.N.C.S THEN THE
NORMAL GUIDELINES FOR EARTH LOOP IMPEADANCES ARE

T.N.S NOT HIGHER O.80 OMHS FOR ZE

T.N.C.S NOT HIGHER 0.35 0MHS FOR ZE

CHECK IMMEADIATLY WITH YOUR REGISTERED ELECTRCIAN WHAT METHOD OF EARTHING YOUR SUPPLY IS , IF T.N.S OR T.N.C.S THEN YOU
HAVE SERIOUS EARTHING PROBLEMS WITH THE READING TAKEN ,
SHOCK RISK COULD VERY WELL EXIST , AND THIS NEEDS TO BE ADDRESSED WITH YOUR ELECTRICIAN AS SOON AS POSSIBLE
ISOLATION OF SUPPLY WOULD BE SENSIBLE UNTILL YOU SPEAK TO YOUR ELECTRICIAN.
BLAKEY1963
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby The Renovator » Sat Jun 16, 2007 7:59 am

Thanks for the reply Blakey1963. To be honest with you, I don't know what type of test Scottish Gas performed but the guy did say I had an earthing problem so it looks like your response is appropriate to my problem.
Can I ask if you or anyone else knows how such problems are typically remidied? e.g. Would it mean tearing the house apart to find a specific fault or is it just a case of installing appopriate earthing in one particular location? Reason I ask is because these high readings came from various plug sockets throughout the house.
Please excuse my ignorance on this matter and provide answers as if I was a woman or a child! (which I could well be for the purposes of being ploitically correct!)
The Renovator
Posts: 6
Joined: Fri Jun 15, 2007 5:55 pm


Postby BLAKEY1963 » Sat Jun 16, 2007 9:10 am

[quote="The Renovator"]Thanks for the reply Blakey1963. To be honest with you, I don't know what type of test Scottish Gas performed but the guy did say I had an earthing problem so it looks like your response is appropriate to my problem.
Can I ask if you or anyone else knows how such problems are typically remidied? e.g. Would it mean tearing the house apart to find a specific fault or is it just a case of installing appopriate earthing in one particular location? Reason I ask is because these high readings came from various plug sockets throughout the house.
Please excuse my ignorance on this matter and provide answers as if I was a woman or a child! (which I could well be for the purposes of being ploitically correct!)[/quote]

THE RENOVATER
IF YOUR PROBLEM,( AND OBVIOUSLY THIS IS IF,)
IS THAT YOU HAVE A MEANS OF EARTHING PROVIDED BY YOUR REGIONAL ELECTRCITY SUPPLIER AND ITS VALUE IS BELOW 1 OMH,
THEN YOUR ELECTRCIAN WOULD CHECK FOR CORRECT CONNECTION
OF AN EARTHING CONDUCTOR TO THIS PROVIDED POINT OF EARTHING,
KNOWN AS THE MAIN EARTH TERMINAL.
THIS EARTHING CONDUCTOR FROM THE MAIN EARTHING TERMINAL
GOES TO YOUR EARTHING TERMINAL AT THE CONSUMER UNIT.
ONCE THE EARTH LOOP AT THIS POINT CAN BE TESTED AT LESS THAN
1 OMH ( AS SCOTTY GAS IS TELLING U ) . THE VARIOUS C.P.C.S
FOR YOUR INDIVIDUAL CIRCUITS ( THE BARE COPPER WIRES WITHIN THE TWO CORE CIRCUIT CABLES, WHICH HAVE GREEN AND YELLOW EARTH SLEEVEING ON ) NEED TO BE CONNECTED TO THIS EARTHING
TERMINAL.
SO THEN AS LONG AS ALL THESE CONNECTIONS ARE COMPLETE AND SOUND .THEN YOUR EARTH LOOP IMPEADANCE READINGS SHOULD
BE ACCEPTABLE DEPENDING ON EXTERNAL EARTH LOOP IMPEADANCE
AND IMPEADANCES FROM CIRCUIT CABLES ( R1 +R2 )
EARTH READINGS SUITABLE FOR TYPE OF PROTECTIVE DEVICE (MCB)
THE ONLY TIME THAT TOTAL DISRUPTION COULD BE POSSIBLE IS IF YOUR ELECTRICIAN IS TO OBTAIN TEST RESULTS OF UNSATISFACTORY CONTINUITY , INSULATION , OR EARTH LOOP IMPEADANCE READINGS FROM ANY OF YOUR CIRCUIT CABLES.
IT COULD BE A CASE FOR REPLACEMENT OF ANY FAULTY CABLES
BY REWIRING.
MY ADVICE, DO NOT DELAY, PLEASE CONTACT YOUR ELECTRCIAN
IMMEADIATLY. EARTHING PROMLEMS HAVE BEEN QUOTED AND A POSSIBLE SHOCK RISK EXISTS AND IN SOME CASES FIRE.

GET IT CHECKED ASAP

BLAKEY1963
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby BLAKEY1963 » Sat Jun 16, 2007 5:09 pm

[quote="The Renovator"]Thanks for the reply Blakey1963. To be honest with you, I don't know what type of test Scottish Gas performed but the guy did say I had an earthing problem so it looks like your response is appropriate to my problem.
Can I ask if you or anyone else knows how such problems are typically remidied? e.g. Would it mean tearing the house apart to find a specific fault or is it just a case of installing appopriate earthing in one particular location? Reason I ask is because these high readings came from various plug sockets throughout the house.
Please excuse my ignorance on this matter and provide answers as if I was a woman or a child! (which I could well be for the purposes of being ploitically correct!)[/quote]

RENOVATOR SENT U PREVIOUS RESPONSE TO ABOVE BUT DO NOT THINK U RECIEVED IT.
IF U HAVE NOT CONTACTED YOUR ELECTRCIAN YET YOU MUST DO SO
NOW !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
HE OR YOUR ELECTRCITY SUPPLIER CAN TELL YOU THE METHOD OF EARTHING FOR YOUR INCOMING SUPPLY.
IF IT IS ESTABLISHED THAT EARTH LOOP IMPEADANCES ARE BELOW 1 OMH AT YOUR MAINS BOARD POSITION, THEN YOUR EARTHING IS
OKAY TO CONSIDER THE FUNCTIONING OF YOUR PROTECTIVE DEVICES. ( M.C.B. S / FUSES )
WITH A VALUE OF EARTH LOOP IMPEADANCE BELOW 1 OMH, IT WOULD JUST BE A MATTER OF YOUR REGISTERED ELECTRCIAN, PERFORMING
TESTS ON YOUR CIRCUITS TO PROVE THE EARTH PATH CONTINOUS
BACK TO YOUR MAINS BOARD.
HE COULD ALSO REPORT TO THE BOARD IF EXTERNAL EARTH LOOP IMPEADANCES
WERE TOO HIGH, AS SAID PREVIOUSLY TNS = 0.8 OMH , TNCS = 0.35 OMH.
AT THE MOMENT A SHOCK AND FIRE HAZARD COULD BE PRESENT.
GET YOUR SPARKY IN PRONTO
BLAKEY1963
.
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby sparx » Sat Jun 16, 2007 11:11 pm

Hi further to 'Blakeys' valid comments; for information.
there are 2 main types/methods of earthing an installation, one - going out of favour now, is to use an earth rod outside, connected to your installation, which would require an RCD for protection.(T T) The rod giving a reading typically of a few ohms up to a few hundred ohms depending upon soil type, (on chalk hills locally 60-75 ohms usual).
On older (circa 1960's) installation there may be a Voltage operated trip, identifiable by having 2 earth wires connected to it, not valid any longer as unreliable/untestable.
The other system is a variation of earths provided by supply company, either from cable sheath (TN-S) or from term on side of fused 'cut-out'
(TN-C-S) also called PME. These give the readings approx as suggested.
A visual check at the intake meter position will confirm which you have.
If TT (rod) & RCD is fitted all may be well, but don't delay in finding out,
without wishing to deride the original observation of the gas man he may not be familiar with TT readings, get a good local sparky to look-soon!
regards SPARX
sparx
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Joined: Wed Mar 21, 2007 8:33 pm
Location: The fifth continent.


Postby The Renovator » Sun Jun 17, 2007 11:38 am

Thanks for the replies guys. Quite technical for me to understand but the over-riding theme is understood.

Can anyone tell me what institutions a competent Sparky should be registered with or where I can find a list that tells me which electricians in my area are affiliated with the right associations etc?
The Renovator
Posts: 6
Joined: Fri Jun 15, 2007 5:55 pm


Postby sparx » Sun Jun 17, 2007 6:01 pm

Hi agn,
we are registered with the 'Electrical Contractors Association' (E.C.A), & for our domestic 'Part P' & other routine Inspections & testing services we are members of National Association of Professional Inspectors & Testers
(N.A.P.I.T).
There is also The National Inspection Council for the Electrical Industries Contractors, (NICEIC).
All the above have adverts in the telephone local directories & web sites; all list approved members by area/post code etc.
For domestic work you need to look for the 'Domestic Installer' logo, rather than just 'member of...'
Now also the Government backed 'Trust Mark' scheme gives insurence backed guarentees for companies who sign up to the scheme so if unsatisfactory work done it will be put right at no cost to customer.
Avoid unmarked vans with only mobile number!
regards SPARX
sparx
Posts: 2166
Joined: Wed Mar 21, 2007 8:33 pm
Location: The fifth continent.


Postby BLAKEY1963 » Sun Jun 17, 2007 8:28 pm

[quote="The Renovator"]Thanks for the replies guys. Quite technical for me to understand but the over-riding theme is understood.

Can anyone tell me what institutions a competent Sparky should be registered with or where I can find a list that tells me which electricians in my area are affiliated with the right associations etc?[/quote]

THE RENOVATOR
SPARX HAS GIVEN ACCURRATE , PRECISE INFOMATION , SO I AM SURE HIS WORDS OF ADVICE ARE WELL NOTED,
AND YOU WILL ACT ON THEM.
MYSLEF JUST TO ADD AM A DOMESTIC INSTALLER, CURRENTLY GOING
THROUGH REGISTRATION WITH N.I.C.E.I.C . YOUR LOCAL TRADING STANDARDS CAN HELP , CLARIFY APPROVED CONTRACTERS.
WE AS DOMESTIC INSTALLERS WITH N.I.C.E.I.C ARE TOLD TO ISSUE
CUSTOMER WARRENTIES FOR ALL WORK DONE, AND CONFIRM WITH THE CUSTOMER IN WRITING WHAT IS TO BE CARRIED OUT, AND SIGNED BY THEM, AND THE FINISHED BILL SHOWS THIS WORK CARRIED OUT,
TOGETHER WITH TEST CERTIFICATES , CIRCUIT SCHEDULES, WIRING
ROUTES, AND OTHER INSTALLATION INFORMATION.
ROUTES. AS I SAID RENOVATOR PLEASE GET YOUR INSTALLATION
CHECKED OUT IMMEADIATELY.
I WOULD LIKE TO THANK SPARX FOR HIS INPUT ON THE RENOVATOR,S
INQUIRY.
THANK YOU SPARX ! BLAKEY1963
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby sparx » Mon Jun 18, 2007 10:06 pm

Thanks Blakey , Didn't want to 'horn-in' but feel when someone is trying to do things right they deserve as much help/info as poss. best wishes both,
SPARX
sparx
Posts: 2166
Joined: Wed Mar 21, 2007 8:33 pm
Location: The fifth continent.


Postby BLAKEY1963 » Mon Jun 18, 2007 11:57 pm

[quote="sparx"]Thanks Blakey , Didn't want to 'horn-in' but feel when someone is trying to do things right they deserve as much help/info as poss. best wishes both,
SPARX[/quote]

SPARX
YOU ARE NOT HORNING IN, PLEASE FEEL FREE TO ADVISE ME IF YOU
CAN , I HAVE READ YOUR INPUT ON THIS SITE OVER THE LAST TWO
MONTHS OR SO AND YOU ARE AN INCREDIBLE MAN OF MUCH
ELECTRICAL EXPERIENCE , AND I THINK WE ARE VERY VERY LUCKY
THAT YOU ARE WILLING TO SHARE YOUR KNOWLEDGE ON THIS SITE.
THERE ARE A LOT OF GRATEFUL PEOPLE ON THIS SITE WHO YOU HAVE
GUIDED, MYSLEF ONE OF THEM.
I WANT TO THANK YOU THE SHORT TIME I HAVE BEEN ON THIS SITE
FOR YOUR HELP AND ADVICE AND LOOK FORWARD TO YOUR
VALUEBLE CONTRIBUTIONS.
ONCE AGAIN THANK YOU SPARX !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

BLAKEY1963
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby The Renovator » Tue Jun 19, 2007 9:17 pm

You guys are both doing a fine job - great that you are willing to offer this advice for free.
To update you, I had a sparky in tonight who specialises in the testing side of things.
The problem lies with my main supply provided by Scottish Power. It enters my house via a live and neutral feed and there is no earth present. My (recently installed) domestic wiring seems to be sound but the main supply is estimated at 60 years old, which ties in with the history of the house (which has been family owned since 1980).
The reading on the plug sockets tonight was 626 ohms and the sparky informed me that this would have been the case before my re-wire.
Will give Scottish Power a bell tomorrow so that this one can be dealt with ASAP.
Anyone know if they will charge?
Anyway, thanks again guys, good to see theres still a bit of passion around when it comes to keeping people (and their families) safe.
The Renovator
Posts: 6
Joined: Fri Jun 15, 2007 5:55 pm


Postby BLAKEY1963 » Tue Jun 19, 2007 10:38 pm

[quote="The Renovator"]You guys are both doing a fine job - great that you are willing to offer this advice for free.
To update you, I had a sparky in tonight who specialises in the testing side of things.
The problem lies with my main supply provided by Scottish Power. It enters my house via a live and neutral feed and there is no earth present. My (recently installed) domestic wiring seems to be sound but the main supply is estimated at 60 years old, which ties in with the history of the house (which has been family owned since 1980).
The reading on the plug sockets tonight was 626 ohms and the sparky informed me that this would have been the case before my re-wire.
Will give Scottish Power a bell tomorrow so that this one can be dealt with ASAP.
Anyone know if they will charge?
Anyway, thanks again guys, good to see theres still a bit of passion around when it comes to keeping people (and their families) safe.[/quote]

THE RENOVATOR
GOOD NEWS YOU GOT A SPARK IN .
JUST ASK SCOTTISH POWER IF YOUR SUPPLY THEY HAVE GIVEN U
IS ONE THAT INCLUDES AN EARTHING FACILITY , I.E T.N.S OR T.N.C.S . ( THEY WILL TRY AND CORRECT IT SHOULD IT NOT BE PRESENT ) . IF THEY DO NOT PROVIDE AN EARTHING FACILITY THEN
YOUR SUPPLY IS WHAT IS KNOWN AS T.T SYSTEM.
SCOTTISH POWER SHOULD NOT CHARGE U FOR CLARIFYING THE METHOD OF EARTHING ON YOUR SUPPLY , AND IF THERE IS ONE PROVIDED BY THEM, THEY ARE RESPONSIBLE FOR GETTING IT TO A CERTAIN VALUE.
LASTLY IF YOUR SUPPLY IS A T.T SYSTEM , THEN YOUR SPARKY WILL HAVE TO PROVIDE U WITH A METHOD OF EARTHING, NORMALY AN EARTH
ELECTRODE ( EARTH ROD ) AND FIT R.C.D . PROTECTION ON YOUR MAINS BOARD . YOUR 16 MM2 EARTHING CONDUCTOR WOULD COME FROM THE EARTH ROD TO THE EARTH TERMINAL ON YOUR MAINS BOARD.
LET US KNOW WHAT METHOD OF EARTHING THE BOARD SAY U HAVE.
BLAKEY1963
P.S IF YOU ARE LEFT WITH A TT SYSTEM WHERE YOUR EARTH LOOP
IMPEADANCE IS FOR EXAMPLE HIGH AS IT IS NOW 600 OMHS + THEN
YOUR SPARK WILL ADVISE ABOUT THE BEST WAY TO PROVIDE R.C.D
PROTECTION FOR ALL CIRCUITS.
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby BLAKEY1963 » Tue Jun 19, 2007 10:41 pm

[quote="The Renovator"]You guys are both doing a fine job - great that you are willing to offer this advice for free.
To update you, I had a sparky in tonight who specialises in the testing side of things.
The problem lies with my main supply provided by Scottish Power. It enters my house via a live and neutral feed and there is no earth present. My (recently installed) domestic wiring seems to be sound but the main supply is estimated at 60 years old, which ties in with the history of the house (which has been family owned since 1980).
The reading on the plug sockets tonight was 626 ohms and the sparky informed me that this would have been the case before my re-wire.
Will give Scottish Power a bell tomorrow so that this one can be dealt with ASAP.
Anyone know if they will charge?
Anyway, thanks again guys, good to see theres still a bit of passion around when it comes to keeping people (and their families) safe.[/quote]

RENOVATOR
U COULD COULD ASK THE LIKLEHOOD OF THEM
GROUNDING THE NEUTRALS WITH THIER SUPPLY TO GIVE T . N . C . S
IF A T.T SUPPLY .
BLAKEY1963
BLAKEY1963
Posts: 654
Joined: Wed Jun 13, 2007 10:57 pm


Postby The Renovator » Wed Jun 20, 2007 11:54 am

Scottish Power are coming out tonight. By the sounds of it they will just do what ever is necessary to get the reading to what it should be.

I asked the sparky who fitted originally the board about R.C.D . PROTECTION and he said he left it out because I have an old house and in such circumstances fitting R.C.D tends to make things trip all the time! Are you saying, however, that if I get my current problem sorted out then R.C.D protection won't be necessary?
If it is necessary then is it just an upgrade to the fuse box or does it entail upgrading every socket in the house (excuse my ignorance again).
The Renovator
Posts: 6
Joined: Fri Jun 15, 2007 5:55 pm


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