-
how bright are fluorescent tubes?
we’re apply for planning permission for an internally illuminated sign box where the customer has specified white fluorescent tubes, and we need to give a guide to the level of illumination for the planning dept.
they’re asking for the light level in cd/m2 (candles per metre squared)
and wondered if anyone has a idea what the average light output is of
fluorescent tubes? 😕 -
23 Replies
-
All tubes are different depending on Wattage, type (daylight, Cool or warm white tubes) etc you then have to factor in the Acrylic panel & graphics if you are covering majority of the panel. If you are going to order a lightbox in from a supplier they should be able to give you the spec of the box you wish to order
Kev
-
Laterally speaking, try persuade customer to have candles instead of flo tubes, should make the maths a lot easier….. i.e. sq m of open side of box / number of candles = cd/m2 at source.. 50% of that for 5mm opal acrylic… job done.
:lol1:
Ian :lol1:
-
suppliers have suggested that we ask the fluorescent tubes manufacturers for this information – anyone know the names of tube suppliers?
-
Not that I would ever suggest doing anything like this – but some unscrupulous types might be tempted to find out the maximum cd/m2 output allowed by the planning dept. and quote a figure 20% less than this 😕
-
Surely it will depend on the tubes that your supplier is using. i would try another company because a light box supplier that cannot supply this info is not a good supplier. Plus it is not as simple as multiplying the figure for one tube.
Phil
what do you do when they come down & check it. Havering council checked an install of mine because of it being on the Southend Arterial Road. Luckily i had asked my light box supplier & they supplied the right answer.Kev
-
quote Kevin Flowers:Phil
what do you do when they come down & check it. Havering council checked an install of mine because of it being on the Southend Arterial Road. Luckily i had asked my light box supplier & they supplied the right answer.Kev
It’s not an issue Kevin – I wouldn’t dream of doing something like that
-
quote Kevin Flowers:Luckily i had asked my light box supplier & they supplied the right answer.
Kev
They probably arrived at the correct figure by deducting 20% off the maximum cd/m2 allowable 😕
-
There is a generally accepted figure as published by the Institute of Lighting Engineers that is used and accepted by all Councils in England (can’t say for certain about the Welsh or Scottish – you boys seem to have your own ideas!) – in fact the ILE document is quoted by Councils (ILE Report No.5) and states that "the maximum luminance of the illuminated area shall not exceed 800 candelas per square metre".
Almost all of the major sign manufacturers use this figure (or a bit less) & quote this report when they are submitting Advertisement Applications so it should be safe to quote this figure.
An exact figure for a particular light box is virtually impossible to give with any degree of certainty as it is not only dependant on the number & wattage of the tubes used but also the control gear and ambient temperature both inside & outside the signbox – any Council that requires an exact figure is being plain bloody awkward & unreasonable!
Good Luck
Guy
-
quote Guy Burt-Davies:Almost all of the major sign manufacturers use this figure (or a bit less) & quote this report when they are submitting Advertisement Applications so it should be safe to quote this figure.
Kinda like I said – Find out the maximum allowable and deduct 20% :lol1: :lol1:
-
To be honest i think it is all worth while knowing now as we are going to be constantly asked for this sort of info once the whole "Dark Skies Policies" are enforced even more…
ill be honest, its NOT something i agree with, but like most things these days. it will be enforced and we will be expected to abide by it or loose out further down the line. so swatting up on it now maybe a wise bsuiness move.
-
The only way you are ever going to be certain is to buy a light meter and check it once made! The other problem is that even with a meter, you still are can only give a reading at a set distance and you also have the question of background light conditions!
Nightmare! 👿
-
Bit of light reading on Candela :lol1: :lol1:
-
quote Graeme Harrold:Bit of light reading on Candela :lol1: :lol1:
…………….forgot that bit! lol
-
quote Graeme Harrold:Bit of light reading on Candela :lol1: :lol1:Yep! That was interesting! :lol1:
-
quote Graeme Harrold:Bit of light reading on Candela :lol1: :lol1:
Graeme – thanks for posting that link about candela and after taking the hint for some light reading, I feel I’m no longer in the dark about understanding the brilliant qualities of fluorescent tubes 😀
-
Yes quite an enlightening read, and if I got it right candela is not reliant on the distance of the observer!!! As with most science things, many of the words thrown about day to day have quite specific meanings i.e. Lux, candela, luminescence, brightness etc are quite specific qualities. With digital meter’s starting in the hundreds of pounds, unless this gets out of hand with planning, its best left to the pros.
If it was me, Id do as Phill says and if they do check, bang another layer inside to cut the light down!
-
On the subject of planning…I have just a received an email from one of my clients advising me that the sign proposed for her new shop has finally been approved by planning, but …..wait for it…. we have to change from using a gold coloured vinyl (which is only a small part of the design) to a solid colour!
It’s only taken them about two months to reach that conclusion 🙄
-
quote Phill:On the subject of planning…I have just a received an email from one of my clients advising me that the sign proposed for her new shop has finally been approved by planning, but …..wait for it…. we have to change from using a gold coloured vinyl (which is only a small part of the design) to a solid colour!
It’s only taken them about two months to reach that conclusion 🙄
Could find nothing wrong, but HAD to make a change to show who is in charge………. (hot)
-
recently noticed that the GEC light tubes have the light output on the packaging
-
The other way round this is to wire the light gear on alternate tubes with 2 switches and a)sell it as a power saving feature, and b) allow a lower lighting level to be selected for LABC testing :lol1:
-
but how much will the face ‘weaken’ the light rating on the tubes.
also, do you measure ‘candles’ at night or in the day?
-
Slightly off topic – but who does long-life tubes or indeed LED replacement ones.
Reason I ask is I’m in negotiations for several signs (only worth £2500) – and they MUST carry a 1 year warranty on the tubes as I’m looking at £5k to hire a HUGE crane with operator if it fails before then…and there’s no get out clause.
Dave
-
Walk back into CEF :lol1:
They might know as the LED replacement tube range is increasing all the time.
Log in to reply.
