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Topic Title: BS7671 or BS7909
Topic Summary: Entertainment industry
Created On: 22 March 2008 10:35 AM
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 07 April 2008 12:43 PM
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Avatar for gkenyon.
gkenyon

Posts: 4490
Joined: 06 May 2002

Originally posted by: LuxSparks

Whilst on the subject of Socapex it would be nice to see all shells connected to earth many supplied or hired in are not.

Surely that does not conform to the Low Voltage Directive and the Electricity at Work Regulations (specifically Regulation 8) ? (consider the effect at the socket end when a phase conductor breaks off the connection and touches the backshell - same with a plug end and phase or neutral - live shell ! I understand that the chassis plug or socket may have the shell earthed, but if you connect two cables together , or the socket end is free before connection . . .)

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH

Edited: 07 April 2008 at 12:44 PM by gkenyon
 07 April 2008 01:47 PM
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davezawadi

Posts: 2817
Joined: 26 June 2002

Plugging in live would not be a normal method of use because it would ruin the pins pretty quickly. I don't think I have ever seen that mode of failure, so the risk is probably exceptionally small. Professional users tend to wear gloves anyway because damaged cables are always a real risk.
Some may like to invent a 26pin BS4343 (EN60309-2) of about 150mm diameter as an alternative, but it fails as Socapex are popular because of their small size and reasonable cost.
Is this a regulation looking for a problem?

David

-------------------------
David
CEng etc, don't ask, its a result not a question!
 07 April 2008 02:15 PM
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gkenyon

Posts: 4490
Joined: 06 May 2002

Originally posted by: davezawadi
Is this a regulation looking for a problem?
Regulation 8 is an absolute duty that must be met, not a "SFARP". I didn't write the EAWR, so please don't shoot the messenger.

I have seen this failure mode a few times, particularly when the solder-bucket connectors are badly made off.


Take the point that the connectors aren't suitable for unplugging "live" - but I've seen that done too - when a cable set on fire and the 10A(F) HCB fuse in the dimmer rack didn't blow !


Unfortunately, in addition, the guys unplugging these cables aren't the only people exposed to them backstage - so especially in the case where two cables join, unearthed backshells are still a potential hazard in a fault.



Agree risk is probably low - but if you get "caught out", EAWR means you've broken the law ! Nasty !

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH

Edited: 07 April 2008 at 02:16 PM by gkenyon
 11 April 2013 07:54 PM
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weirdbeard

Posts: 1659
Joined: 26 September 2011

Originally posted by: LuxSparks

Whilst on the subject of Socapex it would be nice to see all shells connected to earth many supplied or hired in are not.


Hi all, I know this posts from a while ago but I've a question about these Socapex plugs, I've been down to help out a local theatre group and there are a couple of extension leads that need repairing.

They have a variety of these leads, some older with metal cable grips which have an earth tail returning out of the plug/socket which has a ring crimp under a grip screw to earth the shell, but all of of the newer cables have a compression gland cable grip, and there is no means of earthing to the shell of the plug socket (Some like this have been bought ready made as recently the past couple of years from a reputable stage electrics supplier)

Looking at it a bit on the web it seems that this practice of leaving a fair lump of unearthed metal is quite widespread.

Just wondered what others have experienced with these and what is the best thing to do (ie alter the manufactured leads by drilling holes and bolting an earth to the shells) or leave them as is?

Thanks for any input.
 11 April 2013 08:06 PM
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rocknroll

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Are you talking about a 19 pin Socapex ????

The shell is usually earthed from one of the cpc circuits within the cable if memory serves me right pin 13 through 18 the tail that comes from the last pin 19 is sometimes used for bonding, often left if not static.

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!"
-------------------------

Edited: 11 April 2013 at 08:13 PM by rocknroll
 11 April 2013 08:15 PM
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weirdbeard

Posts: 1659
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Hi rocknroll, yes they are 19 pins, there are a few varietys of makers and in the more modern ones there is nowhere to earth the shell, the only thing i can see to do would be add an earth point by drilling the shell and bolting a crimp to it.
 11 April 2013 08:18 PM
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rocknroll

Posts: 8908
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Check pins 13 through 18 with a meter to see if one of them is continuous with the shell, the floating lead from 19 is for bonding such as a lighting bar etc;

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!"
-------------------------
 11 April 2013 08:22 PM
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weirdbeard

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There's definitely no continuity between the earth pins and the shell, I can tell by looking!
 11 April 2013 08:26 PM
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Avatar for rocknroll.
rocknroll

Posts: 8908
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Check with a meter when the unit is fully assembled???????, the pin touches the metal, if not connect a lead from any of the internal cpc terminals 13 -18 to where the screws clamp the unit together with a lug.

At one time Stage Electrics used to do a packet of 10 1mm short leads with a brass terminal on specifically for this purpose.

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!"
-------------------------
 11 April 2013 08:33 PM
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weirdbeard

Posts: 1659
Joined: 26 September 2011

Thanks for your help, I guess I'll be bolting an earth on!

Cheers.
 15 April 2013 11:43 AM
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mcoles

Posts: 8
Joined: 16 April 2012

Hi,
The IET will be publishing Temporary Power Systems - A guide to the application of BS 7671 and BS 7909 for temporary events in June 2013.

This book is a complete guide to designing, erecting and using temporary power systems for events and similar purposes. It details the requirements and application of both the relevant parts of BS 7671:2011 The IET Wiring Regulations 17th Edition and BS 7909:2011 Code of practice for temporary electrical systems for entertainment and related purposes. Thorough guidance is given on the planning, design, verification and management of such systems including references to legislation as appropriate. It also considers the duties of those supplying equipment as well as venues that make available power supplies for temporary use. While the focus and examples in the book are geared towards the entertainment and event industries, it will be invaluable to any who design, deploy or manage temporary electrical systems.

The author, James Eade, has worked in the entertainment industry for over 20 years, covering most genres including touring, theatre, corporate events and permanent installations. As well as providing engineering consultancy services, he was until recently Technical Editor of Lighting & Sound International where he introduced and developed the technical content of the publication; he also developed and Chaired the annual industry Innovation Awards. He is involved with various industry trade associations, and represents the industry on many national and international standards panels, particularly BS 7671 and BS 7909. As well as writing and lecturing, he is still active designing and commissioning electrical systems and acting in a consultancy role for several rental companies and broadcasters.

-------------------------
Mark Coles
Technical Regulations Manager
The Institution of Engineering and Technology
 15 April 2013 01:48 PM
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davebp

Posts: 116
Joined: 16 April 2009

In terms of the socapex connectors themselves:

Either, - Class II inserts are used within the shell (for example in tourmate connectors)
or; You can use Rubber expandable sleeving on every termination within the shell, and then oversleeve the whole lot with heatshrink to achieve a level of class II equivalence.
or: You can short all of pins 13-19 together using a commoning ring, or similar and take a flying lead back to the metal shell.

The last two are accepted methods from Annex H BS7909.

Chassis mounted connectors would ideally be on a metallic enclosure, which would achieve connection with a CPC.

Dave.
IET » Wiring and the regulations » BS7671 or BS7909

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