Mixing hard and dimmed power in socapex

[Judge]

I am okay with mixing hot and dimmed power to keep cable count down, just got to know what you are doing. As it becomes a thing that is not idiot-proof.But as Rob says, most Socapex connectors have an inherent flaw in that the moulded insert containing the pins has a sticky out bit that goes into a notch on the metal shell.Instead of the other way around which would make WAY more sense. So if that little plastic sticky out bit breaks off - which it will, your pins insert can rotate and be out of phase with the other end.Then bad things will happen.

 

[adam2]

I could see a real advantage to a new dedicated Ceeform style 18-pole connector in black with slightly bigger or longer pins, anti-tracking dams/sleeves and the inevitably bigger case, but that would probably be no worse than a typical 32/63A size plug/socket.

 

I think this would be an excellent idea... but one that would need considerable clout to develop and push through... (perhaps similar to when motor control cable connectors moved from 3 pole to 4 pole yellow Ceeforms...

 

Cost could be an issue... for example, devices like the PA CON 19 pole bayonet style connector (popular for use with certain brown painted speakers) costs up to three times Socapex compatible connectors. Any potential replacement needs to be affordable to gain traction.

The other thing is ubiquity... We use Soca because it is almost a universal 6 circuit 1.5mm^2 or 2.5mm^2 extension lead, and as such a few spare lengths could be used for lighting, audio or hoist power/control. Being able to use the same cable for so many functions is probably its strongest point and its greatest weakness...

 

Yes, I can see the merit of a new ceeform style connector to replace Socaplex.

 

In my view this should have 13 pins, 6 live and 6 neutral so as to give 6 circuits, and a common earth. I feel that the multiple earths in the present soca are more of a hindrance than a help. The present "spare" earths only encourages people to misuse these for other purposes such as providing 8 circuits rather than the intended 6 circuits, or for motor controls etc.

 

A 13 pin connector with a single clearly marked earth pin would be safe if used for speakers or motor control. Provided that the earth is ALLWAYS used as the earth, then any combination of the other 12 pins may be used for speakers or other purposes if desired.

 

13 pin connectors and 13 core cable should be a bit cheaper.

 

 

 

[Brian]

But 13 core cable doesn't have a nice lay.

[J Pearce]

And how do you then size that single earth? Is a 2.5mm CPC appropriate for 6 10A circuits?

[adam2]

And how do you then size that single earth? Is a 2.5mm CPC appropriate for 6 10A circuits?

 

 

Yes.

 

 

 

 

[Biskit]

And how do you then size that single earth? Is a 2.5mm CPC appropriate for 6 10A circuits?

Yes.

I'd modify the answer to 'probably, but it would depend on length of the circuits, Ze of the building, and loop impedance of any downstream distribution circuits, all of which would be factored into the system design calculations' ;)

[Stuart91]

I'd modify the answer to 'probably, but it would depend on length of the circuits, Ze of the building, and loop impedance of any downstream distribution circuits, all of which would be factored into the system design calculations' ;)

 

Would it be any worse than the existing arrangements using conventional socapex cable?

[J Pearce]

Yes, most conventional socapex has an individual earth core for each circuit. 6 circuits, 18 cores. The proposal above suggested 13 cores and sharing the earth.

 

I'm happy to take the yes answer, I'm not suitably trained or experienced to be able to comment; just suitably trained and experienced to know that it's a question that should be asked.

[Stuart91]

Yes, most conventional socapex has an individual earth core for each circuit. 6 circuits, 18 cores. The proposal above suggested 13 cores and sharing the earth.

 

But at the moment, on an 18 core cable, each circuit has a single 2.5mm core for the earth. The fact that there's another five cores with green and yellow sleeving alongside makes no difference, unless they are bridged at the plugs. (Which raises enough other problems that it seems to be frowned upon)

 

In the proposed Ceeform arrangement, the solitary 2.5mm earth core would be shared between the six circuits. In most scenarios, there would be exactly the same amount of copper available for a fault current path. Would there be any other issues if multiple faults occurred at the same time?

 

I do wonder if 14 core cable, with two cores tied together onto the earth pin, would make more sense.Would 14 cores "lay" any better than 13?

[adam2]

Under all reasonably foreseeable conditions, including reasonably foreseeable fault, failure, or misuse conditions a single earth core would be fine.

 

Firstly, the earth core is the same size as that provided PER CIRCUIT in the present 18 core cable. The presence of additional earth cores not connected to the faulty circuit is not relevant.

 

Secondly a 2.5mm earth cable is good for at least 40 amp circuits. Consider a d0m3stic shower on a 40 amp circuit and in 6mm twin with earth cable. The earth is only 2.5mm and works fine.

 

In the event of very major cable damage, shorts In all 6 circuits are possible, but see point two above and also note that some of the live cores will short to one of the 6 neutrals, they wont all short to the single earth and avoid all 6 neutrals.

 

In the event of an excessive external earth loop impedance, the 13 core cable is no more of a risk than the current 18 core cable.

 

 

 

[CPlater1]

Just with the lay of cables, generally it's 4, 7, 12, 19 cores

[Simon Lewis]

Not disputing the logic of a single CPC, but I would raise the issue that the majority of Soca cable I've ever handled has been 1.5mm^2

 

Although not usable as a safety feature (because we can't guarantee it will always be used this way) it's not uncommon for the six CPCs to be fortuitously commoned through the fixture cases hanging on scaff or truss. There are schemes where the six are deliberately shorted (but see the comments on hoist controllers!)

 

I'd also suggest that 1.5mm^2 cable is often used in pretty long lengths (perhaps even two or three lengths joined together) and can lead to a high CPC impedance. The use of type D MCBs doesn't help either...

[indyld]

I'd also suggest that 1.5mm^2 cable is often used in pretty long lengths (perhaps even two or three lengths joined together) and can lead to a high CPC impedance.

 

This is surely the case and I've often wondered what the results of a CPC impedance test would be on a circuit consisting of a Soca combination of 1.5mm^2 made up from something like 2 x 30M, 2 x 20M and a 5M. When working for a specialist large scale temporary power systems company, there has indeed been system design that included uprated CSAs based on conductor length, much pondering of the Ze, final outlet loop impedance tests etc. but in the real world of jobbing lighting companies the reality is more 'run a ton of multicore back to the rack, plug in, see lights on, fly the truss, next...'

 

As you say, in practice such test results would probably be reasonable due to the sheer amount of metalwork all joined together.

 

Not that things aren't now 10x more electrically safe than when I started out, but even so...

[lightsource]

Just a quick deviation here, there was an instance on an arena tour where motor control and movers were both on Soca, one of the locals plugged a lighting Soca into motor control, and made an interesting but expensive smoke machine for a few seconds.........

[LXbydesign]

Theres no right or wrong. Everyone has a system - and so long as everyone in your outfit knows the system then its fine.

 

Usually better to just allocate an entire socca for hard power - depending what hard powers required, but a lot of the time if its just to power some LED's and low powered items - on a mixed socca of dim and hard I usually assign circuit 6 on each socca as hard power.