UK Legal Details - Sockets - Where is the requirement for separate socket earths to be linked?

[wilmer000]

I have come across a double socket where the earth terminations aren't linked together - Is this illegal (and what regulation do i look at?) or is it allowed, and I just put the loop-earth in one termination and join the unearthed socket with a length of Earth conductor?

 

[DPG]

@Pete999 have you not heard of Ductor testing?
High current low resistance testing.
Megger DLRO is a very common unit.
Mine is only 10A, but they are available up to 600A they stress the conductors to a higher level than the low current testing done by a typical MFT, or DMM.
They also offer a resolution much higher than those given by a typical MFT.
The way that EN 60204-1 is worded it is easily interpreted to require high current testing for all protective conductor networks.
A classic use for a Ductor was to test steel conduit when installed and utilised as the circuit cpc.

Sounds like the high current earth bond test offered by some of the more expensive 'PAT' testers, including my fairly vintage Seaward one which does 25 amp low resistance testing.

Is ductor a trade name like Megger?

 

[netblindpaul]

Sounds like the high current earth bond test offered by some of the more expensive 'PAT' testers, including my fairly vintage Seaward one which does 25 amp low resistance testing.

Is ductor a trade name like Megger?

Very similar concept to the high current test used in PAT.
Ductor isn't a trade name AFAIK.
They are also known as I said above as high current low resistance testers, or micro/milli Ohmeters.
Megger DLRO10HD, DLRO200, Chauvin Arnoux CA6240/6255/6292 for example.
I have the DLRO10HD.

 

[DPG]

Very similar concept to the high current test used in PAT.
Ductor isn't a trade name AFAIK.
They are also known as I said above as high current low resistance testers, or micro/milli Ohmeters.
Megger DLRO10HD, DLRO200, Chauvin Arnoux CA6240/6255/6292 for example.
I have the DLRO10HD.

Cheers.

 

[Pete999]

@Pete999 have you not heard of Ductor testing?
High current low resistance testing.
Megger DLRO is a very common unit.
Mine is only 10A, but they are available up to 600A they stress the conductors to a higher level than the low current testing done by a typical MFT, or DMM.
They also offer a resolution much higher than those given by a typical MFT.
The way that EN 60204-1 is worded it is easily interpreted to require high current testing for all protective conductor networks.
A classic use for a Ductor was to test steel conduit when installed and utilised as the circuit cpc.

I have heard of Ductor testing, although I have never had the opportunity or experience of operating such a tester, was only asking out of interest.

 

[DPG]

Those testers look like they have an amazing level of accuracy. Reminds me of the short circuit location testers we used to use on circuit boards.

 

[pc1966]

Yes, fantastic to be able to resolve 10 microhoms!

I really want one now, but can't justify spending £2k-ish for my tool collection

 

[nicebutdim]

I have heard of Ductor testing, although I have never had the opportunity or experience of operating such a tester, was only asking out of interest.

I think confusion can arise from use of the "more information" emoticon as it looks very similar to "disagree"

 

[netblindpaul]

Those testers look like they have an amazing level of accuracy. Reminds me of the short circuit location testers we used to use on circuit boards.

They are a 4 wire bridge measurement type device, so they automatically "null" out the lead resistance and you can even use them with two 50m wander leads within limits.
For me it was well worth the cost.

 

[Lucien Nunes]

I have a vintage one (naturally). I think the actual trade mark is 'Ducter' with an 'e', which is registered to Megger having started out as an Evershed and Vignoles product around the same time as the Megger.

 

[netblindpaul]

I have a vintage one (naturally). I think the actual trade mark is 'Ducter' with an 'e', which is registered to Megger having started out as an Evershed and Vignoles product around the same time as the Megger.

I always thought that as it started as "Con_ductor_ Tester", it was ductor, rather than "Con_ductor Tester_".
Though I wouldn't want to argue or labour the point as E&V have been gone a LONG time now!
Most of the modern references are to Ductor rather than Ducter, which adds to the confusion.

 

[Lucien Nunes]

I agree with your logic but perhaps it became genericised as 'Ductor.' I really can't think what it says on mine, and I'm not near it to look.

 

[Strima]

I've just had a response from Electrical Safety First:

Hi,

Thanks for your email. This issue is known to us and we are looking for a solution. The standard doesn’t really cover this and we raising it with the BSI committee at their next meeting – we have already notified the Chair.

Thanks again for bringing this to our attention – we have several examples of the same/similar product and share your concerns.

Kind regards,

Enquiries

So it looks like they're on the case.

 

[westward10]

Nice work @Strima

 

[DPG]

Great stuff. Hopefully these sort of things will get taken off the market.

To be honest there should be a full recall, or even a check of any installation.

 

[Lucien Nunes]

I've now received the socket from @Strima. It's like the curate's egg, some bits look OK. I'll get the camera out and get waffling.

 

[brianmoooore]

Anyone had a word with CEF?

 

[Doomed]

Hang on - does this mean that if you only connect to one earth terminal the other socket is not earthed for any appliance plugged into it?

 

[Avo Mk8]

Hang on - does this mean that if you only connect to one earth terminal the other socket is not earthed for any appliance plugged into it?

Yes

 

[Doomed]

wow - quality

 

[nicebutdim]

Anyone had a word with CEF?

Been wondering if all of these sockets are of the same manufacture or if there's a decent original that has been badly copied?

 

[Lucien Nunes]

Interesting idea that I can kind-of believe. There was a strap across the back that was snapped off and lost during reverse-engineering of the original, and never made it onto the bill of materials for manufacturing the clones. But then, it seems unlikely that the original would have had two terminals. It's just odd.

 

[nicebutdim]

Interesting idea that I can kind-of believe. There was a strap across the back that was snapped off and lost during reverse-engineering of the original, and never made it onto the bill of materials for manufacturing the clones. But then, it seems unlikely that the original would have had two terminals. It's just odd.

It's the fact that CEF stocks it that makes me wonder this, although I'd be prepared to believe that theirs are no different. I doubt that people who copy products worry to much about fully understanding function or why a design might have certain features, when they could be omitted to save fractions of a penny per unit.

Two earth terminals is fairly common on 2 gang sockets these days, so the jury is out in my mind. They might all be junk or there could equally be an original with linked terminals. Either way I don't think it's ideal that these are widely available, considering how many sockets are likely to be upgraded to USB units by homeowners.

 

[Strima]

Two earth terminals is fairly common on 2 gang sockets these days, so the jury is out in my mind.

If one leg of the CPC was placed in one terminal and the other leg in the other terminal the CPC would not be continuous. If both legs of the CPC were terminated into one terminal the other side would be unearthed, not good when using class 1 equipment.

If placed at the end of a radial circuit then one side would remain unearthed.

If the socket was fitted to a metal backbox then the risk would be reduced but as most boxes have a floating lug then continuity cannot be assured.

The above scenarios are based on DIY installation where testing is very rarely carried out.

Bit of a no brainer for me, I wouldn't install one and would strongly advise a customer to remove it if I saw one fitted.

 

[nicebutdim]

If one leg of the CPC was placed in one terminal and the other leg in the other terminal the CPC would not be continuous. If both legs of the CPC were terminated into one terminal the other side would be unearthed, not good when using class 1 equipment.

If placed at the end of a radial circuit then one side would remain unearthed.

If the socket was fitted to a metal backbox then the risk would be reduced but as most boxes have a floating lug then continuity cannot be assured.

The above scenarios are based on DIY installation where testing is very rarely carried out.

Bit of a no brainer for me, I wouldn't install one and would strongly advise a customer to remove it if I saw one fitted.

I get the issue with the socket in question, but that issue is separate to the point I was trying (or rather failing) to make.

It was pointed out that CEF is selling a similar product and the implication was that their product would similarly be affected by this earthing issue. This raised the question in my mind whether this was a poorly designed product from one manufacturer, being sold under several brand names, or if there is a good quality original that has been badly copied by someone more concerned about profit than attention to detail.

The majority of sales made by Amazon will be made to consumers, most of whom will never be aware of potential earthing issues, and it frightens me to think how many installations may be relying on back boxes to maintain continuity, with many more having no continuity of CPC where dry wall or plastic surface boxes are fitted.

 

[loz2754]

I get the issue with the socket in question, but that issue is separate to the point I was trying (or rather failing) to make.

It was pointed out that CEF is selling a similar product and the implication was that their product would similarly be affected by this earthing issue. This raised the question in my mind whether this was a poorly designed product from one manufacturer, being sold under several brand names, or if there is a good quality original that has been badly copied by someone more concerned about profit than attention to detail.

Only testing will tell

 

[nicebutdim]

Only testing will tell

If I'd had time to drive to CEF today, I'd already have the answer.