Earth Loop failure

[robski002]

Hey all, I have an electrical issue with my own house. I had a dishwasher stop working and Hotpoint sent a guy out to repair, he refused to repair saying all kitchen sockets failed ELR test, details below:

Pre-Intervention Checks:

Earth Loop Impedance: 999

Earth Continuity: 0.01

Insulation: 113

Now I had a kitchen fitted about 2 years ago, the fitter also replaced a couple of sockets that were on view from old plastic white ones to chrome front plates. One of these were behind the bins that was never actually used since due to being in an awkward spot. I bought a basic socket checker and discovered that socket was wired the wrong way, live and neutral were reversed. I have rewired it myself and now it is giving three green lights. I'm shocked (thankfully not literally) that he could have done that as it is clearly marked L and N, but the house didn't burn down so I've that to be thankful for.

Getting to my point, would that have likely been the issue to cause the ELR test failure or is that unrelated, there is a callout fee for the Hotpoint repair man so I don't want to bring him back if that would not possibly be the issue? Thanks!

 

[crystal ball]

I would get your earthing checked at source firstly do you have a pic of the meter position

 

[JohnW2]

.... I bought a basic socket checker and discovered that socket was wired the wrong way, live and neutral were reversed. I have rewired it myself and now it is giving three green lights. I'm shocked (thankfully not literally) that he could have done that as it is clearly marked L and N, but the house didn't burn down so I've that to be thankful for.

In fact, in most situations having L & N reversed will not cause problems. The greatest 'risk' is probably that if there are switches which switch only the L (what 'they think is L'!), things may remain live when one thinks they aren't, because they have been 'switched off'.

Getting to my point, would that have likely been the issue to cause the ELR test failure or is that unrelated ...

I don't think there is any way in which it could be directly related. However, if someone made such a basic mistake as you describe, one has to wonder what else they may have got wrong!

Kind Regards, John

 

[ericmark]

To quote

NOTE 2:* The resistance of the installation earth electrode should be as low as practicable. A value exceeding 200 ohms may not be stable. Refer to Regulation 542.2.2.

however 1533 Ω is within the limits for a 30 mA RCD with a TT installation, so question one has to be what is the earthing arrangement for the home?

Next has to be 999 what? Ω, KΩ, or MΩ? Same with Insulation: 113 is this Ω, KΩ, or MΩ? at 999 I would assume limit that his meter will test to? But the plug in socket tester

Loop Detection Ranges <1.8Ω, 1.8Ω - 92Ω, >92Ω the cheapest I could find with loop and RCD test, so why did the socket tester not show the fault? OK the testers are not really good enough when a ring final on a TN-C-S want 1.39 Ω but it should have shown the fault, and one also questions if the RCD works?

As said we are one of the few countries where polarity matters, due to having fuse in line side only of a plug or FCU other countries have reversible plugs. But how could he miss having line and neutral swapped when testing for the minor works certificate? I can understand getting it wrong, I have worked fitting 20 odd sockets and not noted when opening second box line and neutral position reversed, but showed up as soon as I came to test. And I was more careful after that.

I have looked for socket faults in the past, and it can be time consuming. If no earth connected with a ring final there must be two faults, this can be pain staking to find both, the £43 for the tester I found at toolstation would be well worth the money rather than undo every socket hunting for the fault, one would hope to find both faults before opening sockets, but once one is found, it is a laborious process to open one socket at a time and check continuity between both earth wires.

I remember doing it once, after the lady of the house got a shock from her washing machine, only to find the fault was in the loft space, and no access. The farmer took his hat off and unplugged the washer, saying that's why I wear a hat.

The big question is DIY or call an electrician, depends what test instruments you have? 113 MΩ is a pass, 113 KΩ is really a failure but you may get away with it, 113Ω is a turn off power until fault found, insulation tester found a new one for £35 and a clamp on meter to measure down to 0.001 amp also £35, but when I looked for a continuity tester that used the required 200 mA or a RCD tester the prices went over the £100 each, hire is the other way, but again £65 to hire, as have to be calibrated after every hire so not sure worth doing as DIY.

 

[Murdochcat]

Were the sockets actually reverse polarity ?

I would recommend a test or 2 at the CU by somebody with proper test kit AND competence to be sure

 

[JohnW2]

Were the sockets actually reverse polarity ?

His socket tester apparently said that they were, and it's hard to see how such a device could get that wrong.

 

[robski002]

Hi all, thanks very much for the replies, it is much appreciated! Yes the fitter put the wires in incorrectly, however he only went near 2 double sockets, it was one of those that was wired wrong. I have fixed that myself, I found it with the help of the basic version on the Kewtech plug in which I bought. However I have now ordered the Loopcheck 107 version which should let me know if that was related to teh fault and if it is now working, but I take onboard that it is unlikely JohnW2.

I'm assuming EricMark that the repairman didn't check all sockets at all, just to find an excuse not to fix the actual dishwasher, he found the fault that the main board was not working, I had previously been told by an appliance dealer I know that they literally go all the time in that model.

Murdochat, yes they were actually reversed, the socket tester said so and when I opened it up the brown and blue were reveresed, swapping that gave three green lights.

Once again thanks all for your feedback, I'll update once I have the new Loopcheck tester and will report back for your interest. Thanks!