Is this needed?

[CBW]

So I have already done essential electrics course, then company brought Martindale to do some in house training regarding safe isolation. They also sold some kit (proving device, 2 pole voltage tester, and a easy check plug - EZ650 kit). Now my plug showed some faults with the earth arrangement, got it checked by one of our sparks and he said it’s fine must be the Martindale checker. I was told it’s required to check the earth loop impedance for working on appliances such as replacing a boiler pcb - is it necessary? Also what is it really used for, checking I have a decent earth connection? I work for RSL so testing is frequently carried out anyway.

Thanks

 

[EFLImpudence]

Remember first that the EZ cannot distinguish between Neutral and Earth.

The Earth Loop is nothing to do with working on appliances (other than it must be low enough for the circuit). They do not give specific readings anyway - just below a certain fairly high value or not, I believe).

They are used by people who do not actually do electrical work.

You can use it as a rough guide - like neon voltage detectors - but other than that, it is virtually useless. Use the proper meter.

 

[EFLImpudence]

What did it say was wrong with your socket?

 

[CBW]

What did it say was wrong with your socket?

I checked it on a couple of jobs and confirmed with Martindale it was duff, I wasn’t supposed to send it back, just didn’t get the time.

I can’t remember, it was a while back. I think it’s just gave an incorrect reading, possibly an open earth. I first checked it as it was shown to me which was on a boiler. Using the probes on L and N and earth crocodile clip (to earth spade connector). So I don’t need to use it or invest in anything? All I want to know is I’m working safely and to wiring regs.

My work consists of mainly the following:

• Pcb replacements
• Reconnect main earth bonding to Gase or water
• Alter or renew wiring to boilers (all at fcu)
• Renew a fcu front (switch)
• Renewing thermostats
• Renew the odd electric shower (like for like)
• Might get the odd zone valve to change

 

[EFLImpudence]

Pcb replacements
Alter or renew wiring to boilers (all at fcu)
Renew a fcu front (switch)
Renewing thermostats
Might get the odd zone valve to change

As the maximum Earth Loop for a 3A fuse is 22Ω, anything acceptable to the EZ would be alright.

Although, again, it is not really related to your repair work; but just making sure the circuit is alright.

Reconnect main earth bonding to Gas or water

Ok.

Renew the odd electric shower (like for like)

It would be advisable to check the Earth Loop(Zs) for that but still not related to the work, as such.

 

[ericmark]

As a precautionary measure Martindale Electric is voluntarily recalling all EZ150 / EZ650 socket testers with serial numbers between 50 000 000 and 213 999 999 and will replace them with new EZ150 / EZ650 products with a full 2 year warranty.

Was yours one of that batch?

Most sparks will use a full meter, so have very little experience of the cheap plug in tester, I have never used one.

Although your two prong tester and proving unit will show if a correctly wired circuit is dead or not, it will not alert you if there is a borrowed neutral, be it a clamp on meter, or simple neon screwdriver both can alert you of a borrowed neutral before you find out the hard way, so I try to use a neon screwdriver when disconnecting circuits if my clamp on is not handy.

This house when I came to sort out central heating had 3 FCU's connected to 2 separate consumer units. And I would guess it was done by the electricians who wired up the granny flat under the main house. This link is BS7671:2008 forms but it shows you on the minor works form what you should be checking, see page 9 it is clear you can't complete that form with the test gear you have, I know many of us do miss doing the tests, in the same way I have I am sure on the odd time exceeded the speed limit, but only you can assess if it is likely to come back and bite you.

For a DIY job I would not worry, but at work that's a different thing, we all make errors, and even with testing it can still go wrong, but when my firm asked me to do mechanical work I refused, they insisted, I had an accident, that cost them many thousands of pounds in compensation and lawyers, had I not refused don't know what would have happened, it was not my fault by the way, but first question from safety officer was did you do a risk assessment, I answered no, the method statement was locked up, so could not do the risk assessment without the method statement, next question is why didn't you refuse the job, answer was I did, end of interview, I never worked again. I was lucky I did do it right and I was a Union member and they fought the case.

Be very careful doing work which is not your job when employed, as DIY OK, but employed it's very different.

 

[JohnW2]

Remember first that the EZ cannot distinguish between Neutral and Earth. The Earth Loop is nothing to do with working on appliances (other than it must be low enough for the circuit). They do not give specific readings anyway - just below a certain fairly high value or not, I believe).

I suppose that depends upon what you view as a "certain fairly high value". It would appear, for example, that the EZ650 can tell you wheter the EFLI is above or below 1.7Ω ...

Kind Regards, John

 

[EFLImpudence]

Yes, I think 1.7Ω is fairly high.

1.7Ω to 5Ω is not much use and 5Ω too 100Ω is virtually useless.

 

[CBW]

@ericmark I don't know if mine is in that batch or not, I'll check and thanks for the indepth reply. Work haven't said anything to me regarding carrying out the electrical work and haven't insisted.

 

[ericmark]

Although I am an electrician, one job the motor vehicle fitters were paid more, so my boss put me down as a foreman motor mechanic, all was well for 6 months, then new boss arrived and said what's going on here, when told he said fair enough, but to comply with insurance I must have some one on the books as an electrician with me. I was working on 200 ton straddle carriers so mixture of mechanical, 24 volt and 400 volt and a bit specialised, so guys put to work with me often did not have a clue what was going on, seemed all a bit silly, but it complied with insurance requirements.

However well trained we are, you can make mistakes, last week I found a lamp not working, in a hurry, grabbed a bulb and fitted it, just a quick flash and failed again, closer inspection I had fitted a 110 volt bulb, didn't know I had any, never thought of reading the box until it failed, now I haven't got any, but I should have checked, and it could have caused the glass to break and cause a fire, lucky no harm done, but it is so easy to make a mistake.

 

[JohnW2]

Yes, I think 1.7Ω is fairly high.

I suppose that, in some senses, it is. However, I presume that devices like this are intended to be used for identifying potential faults in installations which were satisfactory (test-wise) when installed or last inspected. It's pretty unlikely that any fault (or 'deterioration') would result in EFLI rises from something acceptable to something less than 1.7Ω - so if the result one gets (in a TN installation) is 0-1.7Ω it is unlikley that any fault has developed.

1.7Ω to 5Ω is not much use and 5Ω too 100Ω is virtually useless.

Well, the important thing about 1.7Ω-5Ω (or anything higher) is that it means "not less than 1.7Ω"). The 5Ω-100Ω ranges and above are obviously only relevant to TT installations, for which they would give a reasonable indication of how satisfactory the earthing system was.

Kind Regards, John