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Topic Title: SUSPENDED CEILING LIGHTING LAYOUT
Topic Summary: Approx distance between fittings
Created On: 21 January 2008 08:38 PM
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 21 January 2008 08:38 PM
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nlasen

Posts: 166
Joined: 23 December 2006

Hi all, we have had a lighting design sketch done by senates,but they did not have an overlay of the ceiling grid to place them on so have shown them as they felt accepatable. Now trying to organise them into the ceiling grid and am having trouble positioning them to make it look right, the fittings are twin 55W fittings 600x600, with the curved reflectors and peforated centre piece in them . I was thinking of a layout of three tiles between fittings each way , does that sound right, as i thought 4 tiles between them was too far to go . Any programs to assist with ceiling grid/lighting layouts avaialble free to download from anywhere?

All help appreciated.

Nick
 21 January 2008 08:46 PM
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impvan

Posts: 922
Joined: 07 September 2005

google for DIALUX.

There's also ReLux,but I reckon it's harder to learn.

impvan
 21 January 2008 08:53 PM
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markLEDS

Posts: 121
Joined: 09 August 2007

You need to ask the lighting designer, it will depend on the type of luminaire used, ceiling heights etc.

Ask him what the centre to centre distance is of the luminaires. If they say 2.4m then its 3 tiles apart. If they say 3m then it's 4 tiles. Both are fairly standard spacings but it will depend on the characteristics of the luminaires and the lighting level they are trying to achieve.

Mark
 21 January 2008 09:00 PM
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nlasen

Posts: 166
Joined: 23 December 2006

Thanks for the Info guys, The lighting designer is a *****, he is only doing it using some freebie program he got from the manafacturers, the data he has entered seems all wrong to me anyways. I would normally space standard 18w 4 tube fittings at 3 tiules apart, but seeing as these are twin tube 55w i was hoping 4 tiles apart would still do . Will try and probe him further and see what i can get out of him , wont hold my breath though .

Nick
 21 January 2008 09:26 PM
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iansettle

Posts: 778
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Originally posted by: impvan

google for DIALUX.



There's also ReLux,but I reckon it's harder to learn.



impvan


If you use dialux you can also download various company fittings data so that you can get the correct location of fittings.
 21 January 2008 09:30 PM
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Jaymack

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The lighting design should be based on the required lux levels for the useage of the premises. I would space the fittings to fit the grid system; but with spacings just below that of the designer's design, otherwise the required illumination level won't be achieved. This is most important, if there are Q.A. procedures and a final as-built check, is carried out with a luxmeter.
Ideally of course, the designer should have had the grid layout at the time of design - I would throw it back for a proper job, unless there is good justification for not doing so.

Jaymack
 21 January 2008 09:40 PM
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iansettle

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Jaymack
With Dialux you give the software package the required lux and it will calculate and show where fittings are to be located.
 21 January 2008 11:00 PM
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Jaymack

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Originally posted by: iansettle

Jaymack

With Dialux you give the software package the required lux and it will calculate and show where fittings are to be located.


This is from the OP: -
"we have had a lighting design sketch done by senates,but they did not have an overlay of the ceiling grid to place them"

The designer hasn't had his ducks in a row, the constraints of the grid layout would determine the final average Lux levels; but these levels would require to meet the relevant regulations - as a minimum. He/She hasn't had the grid layout, so passed the buck.
An expression that is often erroneously bandied in the project office, when they are pushed for drawing output - "Don't bother with the details, site will sort it out".

Jaymack
 22 January 2008 09:41 AM
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eclipse

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Doing a similar install at the moment,ceiling height is 2.57M high, luminaires are 2 x 34w and we are installing them with a gap of three tiles between.

-------------------------
Thanks

Alan.

Now what was that reg no?
 22 January 2008 12:01 PM
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davezawadi

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You will be lucky if the lighting is sufficiently even unless the ceiling is rather high. I suggest getting someone who knows how to do it properly! 4 x18W fittings spaced 2 tiles each way at 2.4 metres is about right for an office, but 2 x 55W need to be higher to be able to make use of the greater spacing. Anyway good luck!

David

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 22 January 2008 12:52 PM
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markLEDS

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Originally posted by: davezawadi

You will be lucky if the lighting is sufficiently even unless the ceiling is rather high. I suggest getting someone who knows how to do it properly! 4 x18W fittings spaced 2 tiles each way at 2.4 metres is about right for an office, but 2 x 55W need to be higher to be able to make use of the greater spacing. Anyway good luck!



David


How on earth can you make such a statement (a rather impolite on at that) when you dont know anything about the distribution of the luminaire?

If you read the post again it said 2 x 34w not 2 x 55w.

Mark
 22 January 2008 01:08 PM
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OMS

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You will be lucky if the lighting is sufficiently even unless the ceiling is rather high. I suggest getting someone who knows how to do it properly! 4 x18W fittings spaced 2 tiles each way at 2.4 metres is about right for an office, but 2 x 55W need to be higher to be able to make use of the greater spacing. Anyway good luck!


But increasing the spacing due to increased ceiling heights will tend to diminish the illuminace on the working plane but also diminish the uniformity ratio - there is a relationship between height and spacing for a given luminaire distribution.

4 x18W fittings spaced 2 tiles each way at 2.4 metres


How does that work then - assuming a 600mm x 600mm luminaire body and a conventional grid that would be 3 tiles (axially and transversly) - 4 x 18w is also a tad outdated.

but 2 x 55W need to be higher to be able to make use of the greater spacing.


But the increase in height won't change the extremely high directional intensities generated by 55W CFD's - beware of simply examining a design on average illuminance without considering direction.

Personally, I would redesign with a luminaire with a much lower lumen package and align the fittings to the avilable grid to achieve a sensible uniformity.

curved reflectors and peforated centre piece


Out of interest, how will the batwing ditribution achieve suggested illuminance ratios between the walls, ceiling and working plane or floor cavity. (Thinking LG3 or LG7 here)

OMS

-------------------------
Let the wind blow you, across a big floor.
 22 January 2008 02:07 PM
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davezawadi

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Ah what fun, perhaps you should study the literature from the manufacturers. I rather like the 4 x 18w fittings, OMS. And of course you need to know the distribution, thats the basis of the "knowing what they are doing". Anyway I don't provide free design on Tuesdays, and sometimes the questions, and more particularly the posted "answers" cause me significant pain!

David

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 22 January 2008 03:45 PM
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OMS

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Ah what fun, perhaps you should study the literature from the manufacturers. I rather like the 4 x 18w fittings, OMS.


I assume we are talking T8 lamp technology here then Dave - as I said, a tad outdated( if you take a stroll through manufacturers offerings)particularly when considered from the perspective of Part L for example. Consider your 4 x 18w has a lumen package of around 5400lumens and consumes at least 72 watts - a common TCL lamp such as a 34W would give you 5600 lamp lumens and consume 68w - assume that the luminaire light output ratio is identical so more output for less input - you know it makes sense in our pale green climate (and often allows the design team to achieve CO2 savings on a lighting scheme that can be offset aginst less efficient parts of say a cooling solution or DHW provision - or simply just make a building more efficient)

Anyway I don't provide free design on Tuesdays, and sometimes the questions, and more particularly the posted "answers" cause me significant pain!




Not sure of the point you are making there Dave - I merely pointed out that simply increasing the height was not a sensible solution in isolation and questioned the spacing of two tiles when using a 600mm x 600mm modular luminaire in a conventional grid.

OMS

-------------------------
Let the wind blow you, across a big floor.
 22 January 2008 05:42 PM
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markLEDS

Posts: 121
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Originally posted by: davezawadi

Ah what fun, perhaps you should study the literature from the manufacturers. I rather like the 4 x 18w fittings, OMS. And of course you need to know the distribution, thats the basis of the "knowing what they are doing". Anyway I don't provide free design on Tuesdays, and sometimes the questions, and more particularly the posted "answers" cause me significant pain!



David


I know the feeling.

Mark
 22 January 2008 05:47 PM
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davezawadi

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No I'm not rising to that one OMS. You know as well as I do that the luminaire design has a greater effect than the lamp output, particularly where the source is more compact. Pale green makes me see red!!!

David

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 22 January 2008 06:05 PM
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OMS

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No I'm not rising to that one OMS. You know as well as I do that the luminaire design has a greater effect than the lamp output, particularly where the source is more compact


Rising to what David - I particularly emphasised that the LOR of the luminaire was identical in each case so the compact fluorescent at 2x34W has a better efficacy than the 4x18W T8 solution.

I agree that the photometrics of the luminaire will influence the available light output and certain luminaire styles neccesitate lower LOR's to mitigate the high lumen package lamps available (say a 55w PL Lamp)which can be a bit self defeating - competent lighting design seeks to achieve the balance between the two (amongst many other variables)

Pale green makes me see red!!!


Can't see why Dave - man made global warning may be true it may not be true - it may or may not be driving climate change - we are really talking sustainability here - which is clearly a different thing - I see no problem with using resources more efficiently (In fact I make a living from doing just that for my clients )

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 22 January 2008 08:26 PM
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nlasen

Posts: 166
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on the subject of these eergy efficient 2x55w fittings, how many would be ideal on a 10A breaker, i know about taking the total wattage and then multiplying it by 1.8 for start up current, but does thsi still apply to modern electronic ballasts or not, if not, how many would you put on a circuit. I was looking at about 10 fittings per circuit, am i in the right area. The ceiling height we have is approx 2.7m for reference so if we were looking at a 4tile by 4 grid with 4 tiles between fittings then would this provide an acceptable lux level at desk height. Just after some oppinions.

Nick
 23 January 2008 09:57 AM
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OMS

Posts: 22391
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Personally I wouldn't put more than 15 on a 10A Type C.
(and possibly no more than 12)

That said, I would suggest you abandon the 2 x 55w approach - you simply don't have enough ceiling height to utilise the avilable luminaire output.

Personally I would go back to the begining and start your appriasal based on 2x24 or 2x32 watt TLC lamps. This will probably result in a symetrical layout at 2.4m centres ax and tr ie 3 x 600mm tiles between fittings.

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 23 January 2008 06:43 PM
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perspicacious

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"Will try and probe him further"

Nick, I think he's already done that to you

Regards

BOD
IET » Wiring and the regulations » SUSPENDED CEILING LIGHTING LAYOUT

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