Fluorescent Control Cables -Seperation from Mains Feed

[FozzieBear]

We are having our existing elderly 6ft fluorescent fittings changed for dimmable 1500mm T5 fittings in our Village Hall. Being an old 16th century building we are also trying to get rid of all surface fixed cables that have appeared over the years at the same time by installing a large box trunking all the way round the hall at high level. This will not only be a mounting point for new led strip lights and up/down lighters but also enclose a new ring main, supplies to the stage lighting, BT and network cables, PA speaker cables and the Hearing loops well as the new lighting controls.

The electrician has already advised that we need to have separate compartments in the box trunking to keep the mains cables separated from the low voltage which I was aware of. However now we have started doing some pre-work we have discovered the exiting elderly wiring it is to say the least unconventional with four circuit breakers but everything running on a single neutral. His recommendation is to start from scratch installing new supplies in plastic conduit up the roof trusses. This was always in the plan as these would have contained the control wires for the dimming ballasts. The main feed and switch wires were going to be the original wiring installed in the ceiling.
My questions are:-
1) Can the control wires (which I belive are low voltage) be enclosed in the same conduit as the feed and switch wires, or do they have to be kept separate as with data cables?
2) To provide isolation could you use double insulated cable for the control wires and put them in with the feed or is this still a no no?

If they have to be kept separate this means two lots of conduit up each roof truss which will look ugly and defeats the object of removing surface fixed wires and cables.
The contractor is a good electrician and does things by the book but is a bit old school and may not be up to date on some of the newer thinking.
Any advice would be appreciated.

 

[PrenticeBoyofDerry]

My questions are:-
1) Can the control wires (which I belive are low voltage) be enclosed in the same conduit as the feed and switch wires, or do they have to be kept separate as with data cables?

Extra low voltage is the term I believe you should be using! There a number of reasons that data cable should be kept separate, most popular are interference and the voltage rating of the insulation of the two types.

2) To provide isolation could you use double insulated cable for the control wires and put them in with the feed or is this still a no no?

As above

If they have to be kept separate this means two lots of conduit up each roof truss which will look ugly and defeats the object of removing surface fixed wires and cables.

There is containment that has compartment separation within in it.
The contractor is a good electrician and does things by the book but is a bit old school and may not be up to date on some of the newer thinking.

Any advice would be appreciated.

You should be discussing this with the electrician that is going to commision this installation.

 

[FozzieBear]

[quote="PrenticeBoyofDerry";p="3038274 [/quote]

There is containment that has compartment separation within in it.

I assume by this you mean dual compartment trunking. This is an option but not a very aesthetic one due to the curves and shape of the roof trusses.

There is always more than one way to skin a cat and I was trying to get up to speed with current regulations and see what the implications would be for separation. I appreciate you response but you have not really answered my questions unless I take at face value the two reasons for separation:-
1) Interference- Presumably this is not a problem as the control wires are all part of the same system albeit running at extra low voltage.
2) If the control wires are normally run in figure of 8 or similar, then if they are installed in 0.75mm two core round flex which has an insulating jacket then presumably this complies?

You should be discussing this with the electrician that is going to commision this installation.

I will be discussing with the electrician as I have been doing so far but twice now I have made suggestions as to alternative ways to overcome a problem and this has been accepted. As I said I am trying to get guidance and alternative views from other electricians and installers that may have come across a similar problem.
Thanks Again
Fozzie

 

[DaftPunk]

If you're using 0-10v dimming control for the ballasts then the mains and control wiring can be run in the same conduit as long as the control cabling is rated for mains use.

 

[FozzieBear]

If you're using 0-10v dimming control for the ballasts then the mains and control wiring can be run in the same conduit as long as the control cabling is rated for mains use.

Many thanks. That's the sort of info I was looking for. Much appreciated
Fozzie

 

[OwainDIYer]

for 16th century building you should take advise from conservation specialists even if the building isn't listed. Also check whether the building insurer and local council licencing has any special requirements.

Mineral insulated cable can be a lot less intrusive than conduit for switch drops

If you use DMX or DALI (IEC 62386) control for your lighting you don't have to run separate control wires to each fitting - they work on an addressable bus system. You may already use DMX for stage lighting but it can also be used for general lighting.
http://www.lighting.philips.co.uk/subsites/oem/product_pages/light-configurator-features/dali.wpd

You can also get fluorescent ballasts that can be dimmed using DMX or DALI control.

A small Crestron or similar system can reduce the need for complicated switching and multi-gang switches. A panel can simply have a few buttons to call up pre-programmed 'scenes' eg 'meeting' 'sports' 'dinner' 'party'

Consider PIR detectors for triggering lighting and turning it off to prevent lights being left on.

Induction loop cabling can't run inside metal containment and must be run separately from mains and control cables to reduce interference on the loop.

Microphone and line level audio circuits should be wired in Starquad to reduce interference.

Disabled toilet call alarms.