Discuss Earth Leakage Clamp Meter Question in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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aidenj

Have just got a Di-log 6507 and it works fine. An electrician friend suggested we get one to help identify an EL problem we have been experiencing (slight tingle) in a copper hot water pipe coming from the unvented stainless cylinder. Question is this: It is clearly showing a current in the Earth bonding (c.1.2mA) attached to the pipe in the cylinder cupboard- but the reading on the 22mm pipe itself to which the earth clamp is attached is more like 4.5mA. Does this reading on the pipe actually mean anything? Which reading is a true figure? Can the meter accurately read ELC in the copper pipe, itself?
 
Domestic installation - 6years old - new build - pme (checked by EDF 2months ago; they were happy) - rcd protected (no problems with tripping) - bonding complete throughout. Thanks for any help.
 
you could try measuring the voltage, if any between the pipework and the MET.
 
Something we've just noticed - whilst testing as above - the boiler switched itself off - and we noticed at the same time that the reading in the earth bonding went down from 1.2 to 0.37mA and the reading on the pipe went down from 4,5mA to 0.19mA. The boiler seems to be significant. This was repeatable. Any views?
 
As has ben stated earlier, you must ensure that all necessary main bonding is in place and functioning correctly. The boiler itself needs to be checked and soundness of connections confirmed.

TBH you should contact a local spark, explain the problem and they can do these checks for you with the correct test equipment. If you post where you are in the country, one of the sparks on the forum may be in a position to assist.

Many pieces of equipment have earth leakage (typically items with a heating element), but they should not, individually or collectively exceed the value of the RCD (30ma) and the RCD will often trip at a lower that stated threshold. You should not be getting shocks, tingles etc off of pipework.

Regards
 
You should not be getting shocks, tingles etc off of pipework.


​only plumbers should get shocks off pipework.
 
You should check with the technical help for the cyclinder manufacturer as we have found on a lot of new heating kit (showers, megaflows, boilers,etc ) that they use the neutral side to switch the power requirements. We first noticed this when one of my electricians went to change a faulty controller on a towel rail. Although the power lights were off on the control panel it had 230v between neutral and earth on the load side. It is all acceptable as it meets EN requirements.
I would also check that you have a good water earth bond and it may pay to carry out some cross bonding between flow / return / hot / cold pipes around type in case there are any high resistance joints in the system
 
OK, story so far - we have spent c. £400 on "Sparks" to have them confirm that bonding is fine, pme is fine, "all the circuits" are fine, sockets seem fine, total c.7.6mA on cpc at Consumer unit is fine - etc..etc.. . In other words they were not able to explain the "tingle" on the piping.

Since discovering the change in readings above with the boiler firing-up - have investigated that further.

At the pcb in the boiler itself - on the "Mains In " connector - when boiler not fired up, but switched on at the fused spur - 0mA on the earth connection - when boiler first switched on at programmer - 0mA - but when boiler actually fires up (ie ignites and fan switches on - 335mA - which reduces to c.90mA on the EARTH connection to the PCB as the fan "settles down." (Sorry, unvented condensing boiler - 6years old) BUT these numbers are not reflected anywhere else in the installation - no changes recorded in readings at the cylinder or on pipework. c.7.6 mA still reading at CU. Sounds unlikely - but could the reading at the boiler earth be "design" as no other trace of it can be found?
 
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Thanks for that - there are no electrical connections to the cylinder - to try and eliminate as much as poss, we have totally isolated the immersion - even switched off at the CU. Bonding re-done recently, again to try and eliminate it - but will recheck, anyway.
 
Hi Aidenj, at least you are conscientious and trying to sort the issue,
but from experience sometimes you need to take a deep breath step away and put it in the hands of the manufacturer (document all correspondence, we always try to communicate via email)
Over the (many) years we have spent masses of our (unpaid) time trying to sort out an issue which the customer believes is down to us only to find out that there was a design or manufacturing fault with the equipment we had installed. (12V downlights that kept flickering and switching off for no apparent reason - traced by manufacturer to fact that lampholders not able to deal with heat where lamp pushed into holder J?? lighting / Fused spur timers losing memory and factory reesetting after 6months, FS?11? by T?megu?rd (design fault -faulty PCB), Low energy floodlights Burning out 58W Lamps (design fault with lampholder - ET?rnA Lighting) I could go on.
Problem being is that you end up being lumbered with sorting out an issue not of your making - and I would guess that ideally you have not set up your company as a non profit making organisation
 
We're falling between stools here -.... it seems that Gas Safe, NICEIEC Part P, qualified Plumbticians/Electumbers are in quite short supply.

Recent comment from boiler manufacturer was that they only talk to "Gas Safe" qualified installers. Not helpful when the problem might be an electrical £200 pcb, that one doesn't want to replace, just in case it is the problem. This seems to be the "plumbers" solution. Fine if they are right - but unnecessary expense if not.

No NICEIC electricians that we've found seem (on the phone anyway) able to say that a faulty pcb might be working perfectly well controlling the central heating system, but at the same be creating a 335mA reading at times on the main earth connection. "No - definitely can't be right" - but it is working ok?

As they say - electricity and water don't mix!
 
Not entirely related but might cheer the poster up a bit. I'm working in a hotel where circuit earths (where present) occasionally present anywhere between 90 and 120 VAC. Sometime sthey splash a bit on re-connection.

Zs is impossible meter just screams

I am almost at the point of screaming too. Wierdly, there is 0V to water earth bond or pipework
 
Not entirely related but might cheer the poster up a bit. I'm working in a hotel where circuit earths (where present) occasionally present anywhere between 90 and 120 VAC. Sometime sthey splash a bit on re-connection.

Zs is impossible meter just screams

I am almost at the point of screaming too. Wierdly, there is 0V to water earth bond or pipework

The 90-120v on the earth sounds like a broken earth on a lighting circuit ie holgen lamps hence why Zs cannot be read.
 

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