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Topic Title: Adequate strain relief definition - where is it defined in the regs.
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Created On: 14 May 2013 01:12 PM
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 14 May 2013 01:12 PM
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mikecheshire

Posts: 10
Joined: 14 May 2013

My first post here, so hello all.

I have just taken delivery of some light fittings as part of a larger kit of parts, and in my view they are dangerous!

As a one time owner of large electrical testing company , I have always failed equipment that has no strain relief for cable cores, without strain relief for the sheath, even if terminations themselves are protected.

In the case of this equipment (portable lights for business use) the cores are taken through a plastic notch as part of the fitting protecting the termination , but the brown and blue cores are visible coming through the back of the plug, so the strain is taken by the colour cores, and were the cable pulled sideways it would bend at the point of the coloured cores.

I am assuming this is a no brainer violation, but I am struggling to work out where in which regs it says so - and how it actually defines "adequate strain relief" on entry to a portable appliance.

Any ideas anyone? Which regs and what do they say? Is there anywhere it says that strain must not be taken by the coloured cores?.

Also a CE issue. he devices themselves are not CE marked, but the supplier says they do not have to be, only the paperwork. I thought if product could be marked it should be...eg here on the european commission site about CE

http://ec.europa.eu/enterprise...out-ce-marking/


Would appreciate help..
 14 May 2013 01:31 PM
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AJJewsbury

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Is there anywhere it says that strain must not be taken by the coloured cores?.

Most "cord grip" lampholders work by taking the coloured cores through a tortuous path rather than gripping the sheath, so I guess there's no universal prohibition on that. Perhaps it's down to the specific product standard?
- Andy.
 14 May 2013 01:35 PM
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rocknroll

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The regulations that apply to this is the Electrical Equipment (Safety) Regulations 1994.

Take the item along to your local Trading Standards office for us to determine whether the sample to be tested is safe and constructed in accordance with good engineering practice.

Charges will apply for this service often based on an hourly rate.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
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 14 May 2013 01:42 PM
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Thripster

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You could start with 522.8


Regards

And then move on to 559
 14 May 2013 01:43 PM
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mikecheshire

Posts: 10
Joined: 14 May 2013

Originally posted by: AJJewsbury

Is there anywhere it says that strain must not be taken by the coloured cores?.


Most "cord grip" lampholders work by taking the coloured cores through a tortuous path rather than gripping the sheath, so I guess there's no universal prohibition on that. Perhaps it's down to the specific product standard?

- Andy.


Thanks for that, I am not sure I have seen one of those - will have a look. I have certainly not seen anything else with blue and brown stripped so they are visible on entry to the device.
 14 May 2013 01:44 PM
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mikecheshire

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Thanks thripster and rock and roll
 14 May 2013 02:12 PM
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mikecheshire

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By the look sec 520x only says terminations need relief, not the cores.

Thinking about this further, the light cannot be a valid class 2 appliance, ie one not requiring an earth. The idea is a single failure cannot cause an electric shock, normally done by double insulation.

Yet in this case a single break of a plastic lug (the so called termination strain relief) would indeed cause the cable to pull out under strain and leave a flying lead with live and no earth to protect it.

So surely that invalidates the claimed CE - in that it is neither a valid class 1 nor class 2 appliance.

What do others think?

Most portable lights with standard fittings are class 1, or low voltage. This has an unearthed screw fitting with powered screw thread shell.
 14 May 2013 02:24 PM
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OMS

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Originally posted by: AJJewsbury

Is there anywhere it says that strain must not be taken by the coloured cores?.


Most "cord grip" lampholders work by taking the coloured cores through a tortuous path rather than gripping the sheath, so I guess there's no universal prohibition on that. Perhaps it's down to the specific product standard?

- Andy.


as do many ceiling roses in order to support the flex to the lampholder

Regards

OMS

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Failure is always an option
 14 May 2013 02:27 PM
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OMS

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As a one time owner of large electrical testing company , I have always failed equipment that has no strain relief for cable cores, without strain relief for the sheath, even if terminations themselves are protected.


So all ceiling roses then ?

back to your initial post, do you have a photo or can you link to the product website.

You may have a problem, but I'm not certain you do - both in terms of the class 2 argument or adequate strain relief of the conductor rather than the oversheath.

Regards

OMS

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Failure is always an option
 14 May 2013 02:42 PM
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mikecheshire

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Originally posted by: OMS

As a one time owner of large electrical testing company , I have always failed equipment that has no strain relief for cable cores, without strain relief for the sheath, even if terminations themselves are protected.




So all ceiling roses then ?



back to your initial post, do you have a photo or can you link to the product website.



You may have a problem, but I'm not certain you do - both in terms of the class 2 argument or adequate strain relief of the conductor rather than the oversheath.



Regards



OMS


I agree , it is uncertain - conflicting arguments

This is a portable appliance used in an office (unlikely a public place, but possible) , in which case the risk of "kicking the cable" is certainly more than a ceiling rose.

Sorry don't have a picture. There is a single plastic lug trapping each core close to connection for 2mm - where from memory ceiling roses have a labyrinth core path rather than single small lug.

It looks like a ceiling rose type fitting exit, but the brown and blue cores are actually visible protruding from the end of the screw on cap. That means the potential for the brown core to "pull out" beyond the cap is clearly possible if it were kicked and one of the lugs broke.
 14 May 2013 02:49 PM
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AJJewsbury

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Here's an example of a typical ceiling rose arrangement:



(google's let me down - I can't find an image of a wired lampholder with the cover off!)

- Andy.
 14 May 2013 03:06 PM
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OMS

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Is the screw on cap actually a compression gland - and as it's loose, you've been able to see the "pulled" insulation beneath.

I appreciate it's an appliance - a desk lamp by the sound of it - it just may well have been badly terminated at manufacture and the design is OK inherently

What make/type is it - is it bought straight off the shelf or has it had a third party assembler involved.

Regards

OMS

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Failure is always an option
 14 May 2013 11:08 PM
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ectophile

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Most portable lights with standard fittings are class 1, or low voltage. This has an unearthed screw fitting with powered screw thread shell.


None of the portable lamps (table lamps and similar) in my house are class 1. They are all class 2 with twin-core flex.

I'm sure there's quite a few small appliances where you could yank the flex out if you pulled hard enough. I don't think that stops them being class 2.

-------------------------
S P Barker BSc PhD MIET
 15 May 2013 09:05 AM
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mikecheshire

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Here a couple of pictures.
This is clearly not safe by any definition.
The cores protrude, at which point it is single insulated cable.
The strain relief is not even secure - the core is bigger than the hole.





And - incidentally only a single layer of plastic insulates neutral from a metal reflector.

The questions is which regs does it violate?

Edit:The images above are not showing for me, despite being a valid URL any ideas why?

Edited: 15 May 2013 at 09:14 AM by mikecheshire
 15 May 2013 09:10 AM
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AJJewsbury

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The images above are not showing for me? any ideas why?

"New" users links aren't displayed - it's a precaution against spam, I guess the same block is stopping your images.

Allow me...







- Andy.
 15 May 2013 09:12 AM
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gkenyon

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It it's part of a pre-manufactured assembly (as it sounds from the OP - "protable lights"), then I would question whether the Regs actually apply

The Regs require pre-manufactured assemblies to comply with appropriate product standards, and it is the requirements of the product standard that would apply.

CoP for In-Service Inspection for Electrical Equipment + Product Standard + Standard for the Plugs & Sockets used would be the best bet.

It could be said that it's improper termination that's at fault, but I've come across these before, and it's easy to pull the flex and make this happen.

As has been said, legislation at play here rather than simply "Wiring Regs". As it's a work light (assume you're using at work) includes:
- Provision & Use of Work Equipment Regs
- Electricity At Work Regs

I would say not adequately covered by insulation, and, unless normally placed out of reach and adequate strain relief on the flex itself, could be considered hazardous.

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Eur Ing Graham Kenyon CEng MIET TechIOSH
 15 May 2013 09:28 AM
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KFH

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I would fail that on a PAT and would not expect the regs to apply as Graham has stated. It looks as if a compression gland has not been fitted at the back of the plug so the exposed cores are going to rub on the thread and the core has not been wrapped correctly around the strain relief lug so as the OP points out there is no strain relief. I would expect to see a loop of the core around the lug which appears to have been shaped to accept a loop.

I would be sending them back as I would not expect them to last long in use as portable lights.
 15 May 2013 09:30 AM
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mikecheshire

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Originally posted by: gkenyon

It it's part of a pre-manufactured assembly (as it sounds from the OP - "protable lights"), then I would question whether the Regs actually apply



The Regs require pre-manufactured assemblies to comply with appropriate product standards, and it is the requirements of the product standard that would apply.



CoP for In-Service Inspection for Electrical Equipment + Product Standard + Standard for the Plugs & Sockets used would be the best bet.


I agree - it is not really an issue for the regs which are primarily fixed wiring. But it must fall into the categorization of equipment as class 1 - 3 safety - but I do not know which regs defines those categories.

As an (ex owner) of a big elec safety testing company in the north which had a whose who of northern public and corporate bodies as clients, I and my staff would have failed these without hesitation, on the basis of inadequate strain relief , and I know all my competitors of the time would have done the same. (those who actually inspected and tested, rather than just slapped labels on..I digress!) But in hindsight I am struggling to work out what grounds we had other than common sense..

Most safety regs are non proscriptive In the safety testing COP - and by the way a COP does not necessarily have the force of law behind it, sates " 14.5 (iii) ....Check that the cable is properly secured in the cord anchorage - gripping the sheath so that there is no strain on the cable cores or terminations "

But it says that in connection with plugs - we always assumed the equipment exit had to be the same or better, since the risk is greater. A cable pulled from a plug is no longer live. A cable pulled from the equipment certainly can be. But I am struggling to find anywhere that actually says that in black and white.

Edited: 15 May 2013 at 09:37 AM by mikecheshire
 15 May 2013 09:35 AM
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mikecheshire

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many thanks for pasting the images AJJ
 15 May 2013 09:37 AM
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OMS

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By observation, this is just simple poor termination. The compression gland nut is missing and the wire stripper dosn't know which way round the strain lug works.

regards

OMS

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Failure is always an option
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