Advise on SY termination (Stage Lights)

[SUNRAY]

I'm altering stage lighting as part of a refurb and run into a silly little niggly corner.

The 100x50 trunking at the top is at ceiling level, to the right is an office to which I have no access and the other side of the office is the power/dimmer cupboard. Trunking used to continue to the left [red] but has been cut of almost flush with the office wall to make way for the new hole in the wall for cable basket. Originally [red block] this was to have been some 300mm from the ceiling and office wall and my intention was the new SY lighting cables were to come through the hole and straight up, terminating in glands into the trunking [orange].

However the new hole is less than 100mm from the slab and 40mm from the wall with the top of the basket marginally higher than the bottom of the trunking [hole, basket and trunking shown in black].
It's going to be a PITA but I think the cables will loop round into the end of the trunking OK from the hole.
At the dimmer packs there is a large cut out [maybe 150x30mm from memory] between the vertical 50x50mm trunking and side of pack.

My question based on previous discussions is: what are peoples opinions on the best way to terminate the SY cable. At the moment I'm looking at a pigtail into the earth bar once it's inside the pack but I am struggling to find anywhere to provide any mechanical restraint.
The 2 packs, remainder of the buildings switchgear and trunking take up the height and width of the cupboard.
Access to the 100x50 trunking is restricted by a sprinkler pipe running parallel and ~200mm in front.

 

[aptsys]

Is the SY already specified? Why not use flex or T&E as is more common?

 

[Risteard]

Is the SY already specified? Why not use flex or T&E as is more common?

T&E is a cable for domestic applications.

 

[aptsys]

T&E is a cable for domestic applications.

It was used in many theatres around here

 

[JohnD]

but your SY is a digital control cable, is it not? 0.5mm cores or smaller? Often has large numbers of cores? Is this one cable going to each of modern LED lamps? Or multicores going to the packs?

I must admit I don't understand the job here.

 

[SUNRAY]

Is the SY already specified? Why not use flex or T&E as is more common?

Galvanised trunking, conduit, Low smoke SY or armoured specified by consultant...
I chose to do it in trunking, 25mm conduit and kopaflex last time as the runs were very straight but not this time with the horrible routes involved.
SY already installed into IWB's and patchbay and currently waiting at other side of this hole for release of the room then final placement and terminating.
When I saw the drawings and the hole drawn on the wall, complete with test hole to check location both sides a couple of months ago, I managed to drill the new holes in the trunking for the glands before the basket and sprinkler pipe was in the way. It was going to be so easy even with the new obstructions.

 

[SUNRAY]

but your SY is a digital control cable, is it not? 0.5mm cores or smaller? Often has large numbers of cores? Is this one cable going to each of modern LED lamps? Or multicores going to the packs?

I must admit I don't understand the job here.

These are 18 core 2.5mm² multicores between packs and patchbay.

 

[333rocky333]

Your drawing shows 8 cables, what diameter are these 18 core cables.

 

[deadshort]

I bet you're cosultant is M+E and not a Theatre consultant? SY is overkill for this, 1.5mm TRS multicore is standard in Theatre.

What is the patching ? Socapex or 15A tails ?

DS

 

[ban-all-sheds]

T&E is a cable for domestic applications.

Please refer to the regulation(s) that says that.

 

[SUNRAY]

I bet you're cosultant is M+E and not a Theatre consultant? SY is overkill for this, 1.5mm TRS multicore is standard in Theatre.

What is the patching ? Socapex or 15A tails ?

DS

This particular venue insists that the bulk is metal enclosed for screening purposes having experienced interferance problems in the past, hence the lighting refit about 12 years ago. I'm more inclined to believe it had more to do with the fact that it was previously wired by house bashers and the neutrals did not pass through the same route as the lives, ie different conduits and missing the filter network. At that refit I replaced all the plastic tube with galv, kept the singles as pairs in the same tube and wired the packs correctly. Their interference probs went away and they don't want them to return. I confess I like SY for these sort of jobs, may be overkill but it does keep things tidy.
I have never come across multicore TRS for fixed wiring, portable and moving bars yes but not the fixed part. in fact I have seen loads of pyro or fp200 used for the fixed parts.
Patching is 15A Strand patch bay which I tried to convince them to do away with as it is patched 1-1, 2-2 etc and the layer of dust indicates is has not been touched for a while.

Your drawing shows 8 cables, what diameter are these 18 core cables.

They are about 20mm diameter but without the outer sheath and screen they're probably down to about 16mm which is far more manageable when the screens are terminated at the trunking. There is plenty of space for 8 but I am not looking forward to pulling them neatly into the 4m run of 100x50 trunking.
The trunking in question is in the ceiling of the office and it has been made quite clear that removing the plasterboard for access is out of the question, until now it has only had 2.5mm singles in it which are far more manageable. I'd have changed it to 100x100 when I had the opportunity if I'd had an inkling of the current situation but I reckon it may be impossible to change now with the sprinkler pipe in situ. Ironically it turns into 100x100 when it gets above the packs.

 

[SUNRAY]

T&E is a cable for domestic applications.

Not correct, T&E is adequately acceptable for such purposes, in fact I have a school job lined up for the Christmas break which has been spec'd as 1.5 T&E in cable basket. This is for 15A sockets on dimmer packs with 13A C type MCB's.

 

[Simon35]

This particular venue insists that the bulk is metal enclosed for screening purposes having experienced interferance problems in the past, hence the lighting refit about 12 years ago. I'm more inclined to believe it had more to do with the fact that it was previously wired by house bashers and the neutrals did not pass through the same route as the lives, ie different conduits and missing the filter network. At that refit I replaced all the plastic tube with galv, kept the singles as pairs in the same tube and wired the packs correctly. Their interference probs went away and they don't want them to return. I confess I like SY for these sort of jobs, may be overkill but it does keep things tidy.
I have never come across multicore TRS for fixed wiring, portable and moving bars yes but not the fixed part. in fact I have seen loads of pyro or fp200 used for the fixed parts.
Patching is 15A Strand patch bay which I tried to convince them to do away with as it is patched 1-1, 2-2 etc and the layer of dust indicates is has not been touched for a while.

They are about 20mm diameter but without the outer sheath and screen they're probably down to about 16mm which is far more manageable when the screens are terminated at the trunking. There is plenty of space for 8 but I am not looking forward to pulling them neatly into the 4m run of 100x50 trunking.
The trunking in question is in the ceiling of the office and it has been made quite clear that removing the plasterboard for access is out of the question, until now it has only had 2.5mm singles in it which are far more manageable. I'd have changed it to 100x100 when I had the opportunity if I'd had an inkling of the current situation but I reckon it may be impossible to change now with the sprinkler pipe in situ. Ironically it turns into 100x100 when it gets above the packs.

SY is a control cable, and is described as such on all manufacturers data sheets, and offers no screening, the braiding is full of holes.

 

[davelx]

, and offers no screening, the braiding is full of holes.

Clearly visible here - you can see the white insulation through the braid

SY

• davelx
• 20 Jun 2017

However. Eland cables state:
"The voltage rating for these shielded flexible multi-core control cables is 300/500V."

and also:
"SY control cables are not suitable for fixed wiring applications requiring compliance with the requirements set out in BS7671."

so it seems there is some confusion around!

 

[SUNRAY]

SY is a control cable, and is described as such on all manufacturers data sheets, and offers no screening, the braiding is full of holes.

Clearly visible here - you can see the white insulation through the braid

SY

• davelx
• 20 Jun 2017

However. Eland cables state:
"The voltage rating for these shielded flexible multi-core control cables is 300/500V."

and also:
"SY control cables are not suitable for fixed wiring applications requiring compliance with the requirements set out in BS7671."

so it seems there is some confusion around!

Well I'm sorry to say just because there are holes it does not mean that this stuff is screened. The size of the holes dictates the useable frequencies that the screen is most effective over.

What makes this any less suitable for fixed wiring that T&E or TRS? All are commonly seen in such environments.