Socapex earthing

[handyandi]

Have been stocking up on some socapex & reading the Wiki it states that the metal shell should be bonded to at least one of the earth circuits. All the used cables I have purchased so far do not have this earth link.

Looking at the true 'socapex' connectors it should be possible to bond via the screw saddle clamp, but how is the best method to bond something such as the tourmate versions etc.

 

Andi

[Andrew C]

ISTR that the proper Socapex shells have an M4 threaded hole designed for the purpose. The others that I remember where a complete **** and we drilled them. The plastic shelled types were even worse! (I know, but what about the metal part of the insert?)

[Stuart91]

All the used cables I have purchased so far do not have this earth link.

 

I've seen a number of used cables from a variety of sources, and none of them have had the earth link either. From the markings on some, they have belonged to some of the "big names" in the industry so will hopefully have been built to some sort of standard specification rather than just someone bodging around in their garage.

 

They're all definitely intended for use as lighting cables, not speaker circuits, before anyone suggests that.

[Andrew C]

none of them have had the earth link either.

And I've had a significant belt from one that didn't, and it would have been prevented if the shell had been earthed. The regs for fixed wiring require that any extraneous metal work liable to become live in the event of a fault be earthed. From this, I have earthed every bit of socapex under my control.

[Stuart91]

And I've had a significant belt from one that didn't, and it would have been prevented if the shell had been earthed. The regs for fixed wiring require that any extraneous metal work liable to become live in the event of a fault be earthed. From this, I have earthed every bit of socapex under my control.

 

I should perhaps have made it clearer that I'm not advocating leaving the shells unearthed. Just pointing out that earthing shells does not appear to be standard practice for many in our industry.

[J Pearce]

I remember seeing some guidance that only the spiders should be bonded. I presume this is to avoid problems when using the soca for audio or motor power/control.

[adam2]

I believe that without doubt, the metal shell of a socapex connector should be earthed, the fact that many dont bother does not make the practice safe or desirable.

 

What is however less clear, is whether or not the multiple earth wires in socapex should be bonded together or not.

Some say yes, bond all the earths together to give redundancy and/or a lower earth loop impedance.

 

Other say, no, keep the earths seperate since that facilitates the use of socapex cables for other purposes such as multiple speakers, or motor control etc.

 

I would prefer the second approach of keeping all the earths seperate within the cable, and connecting the shell to any one earth.

The use of a single earth wire in a multicore cable is no less safe than the single earth in a 3 core TRS.

 

If desired, redundancy may be provided by connecting together all the earths at any mains rated equipment that is to be supplied via socapex, such as breakout boxes or multi lamp lighting equipment.

[J Pearce]

But what if you only connect the shell to one earth and its used with a tail in spider and the plug that has the shell earth doesn't get used?

 

And how do you decide which pin is earth for all the standards?

 

Surely its best to bond at the spider and let the shell of the spider contact earth the shell of the cable?

[adam2]

I would keep the earths separete within the socapex, but bond them all together at whatever is to be connected to the socapex.

 

In the case of a dimmer with socapex outlet, all the earths will be connected together via the frame of the dimmer.

If a number of 15/16 amp plugs connected to dimmer chanels are to be used, then I would connect together all the incoming earths, but do this in the box were all the 3 core flexs terminate, not in the socpex socket.

[Stuart91]

It's interesting to see the range of opinion on this subject...

 

Does anyone have an authoritative source for the "correct" way of doing it?

[Brian]

Does anyone have an authoritative source for the "correct" way of doing it?

 

From BS 7909:2008, Annex H, Standard Connections for a 19-pin connector for lighting applications...

 

"Note 2 It is important for lighting applications that the metal shell of these connectors is equipotentially bonded with at least one CPC of the cable."

[Bruff]

Does anyone have an authoritative source for the "correct" way of doing it?

 

From BS 7909:2008, Annex H, Standard Connections for a 19-pin connector for lighting applications...

 

"Note 2 It is important for lighting applications that the metal shell of these connectors is equipotentially bonded with at least one CPC of the cable."

 

Our practice is to bond all the earths together at source (usually the 19-pin female connector of the spider) only. This way, the shells are earthed even if only one circuit is connected.

[ArBee]

Hello all,

 

In response to a request for an authoritative response I can respond with the following although I'm not absolutely sure it will meet everyone's expectation due to the nature of the way in which the law/standards approach this.

 

I have leafed through the various standards at my disposal regarding Connectors (IEC 61984 Connectors – safety requirements and test, BS EN 60309 Plugs, socket outlets and couplers for industrial use – part 1 General requirements and BS 7909 Code of practice for temporary electrical systems for entertainment and related purposes.

 

None of the standards I have sets out a definitive method of how the earthing is to be carried out on multipole connectors although it states all the obvious requirements to ensure the earthing can be relied upon to do its job.

 

In terms of the reference to BS7909 (Annex H note 2) – (I should add here this is only for lighting and not motors or sound) I have been in contact with a couple of guys who sat on the committee who have informed me that this issue was debated at great length and the editorial committee wanted it amended/withdrawn. The consensus of the whole of the committee was to keep it as is but I'm assured that this issue will be on the agenda in the forthcoming amendment to 7909 timed to coincide with the forthcoming amendment to BS 7671. I get the feeling they want to explore the connector standards more closely looking into the classification of the connectors and to see if the connector meets the requirements for class 2 insulation. However, I think they may find that unless the connector has double and/or reinforced insulation it cannot be classified as such and then only by the manufacturer. This may be a while coming so It may be that there is an interim guidance document required which, if successful and accepted as a code of practice by you the industry, would fill the gap and then be feed straight into the 7909 amendment when that happens.

 

So where does this leave everyone? Well from what I'm reading those of you who have recognised the hazard have acted as the law would expect. That is with all electrical equipment they should be safe to use (Regulation 4 of the Electricity at Work Act.) and I would recommend that you do that by sound electrical engineering principles. What this does do however is give the committee of BS7909 the task of finding a consensus on the best method to state in their revision of 7909 (if they so choose to adopt the issue?).

 

Problem is this may be a while coming (or not at all) so It may be that there is an interim guidance document required which if successful and accepted as a code of practice by you the industry, would fill the gap and then could be fed straight into the 7909 amendment when that happens.

 

Thoughts? – Is this something the industry would find useful? If so I won't be putting it together – you will by getting involved. I will facilitate the process if there's enough of you wanting to participate and it won't be an exclusive PLASA member excercise, anyone can pitch in.

RB

Ron Bonner

Technical Resources Manager

PLASA