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Topics for Discussion
Click the Title below to go to the topic
We are often asked to advise on which type of recessed downlighters are better - Low Voltage (LV), or Mains Voltage (MV). The simple answer is that they are both great ways to light a room, however, there are some important differences to consider when deciding which to choose and some circumstances that demand you make the right choice.
Key
Differences
Apart from the voltage, there are some important differences between the two
types of light which may help you decide on which is the best for you. You
may have noticed from the website that in the majority of cases we can offer
our downlighters in both Mains Voltage (240v GU10 Halogen)*, and Low Voltage
(12v Dichroic Halogen) versions. When installed the fittings look identical,
as the same castings are used for both. It is the type & quality of light
given out that is the most noticeable difference. Low Voltage Dichroic halogen
will make the colours in fabric stand out more, and give better definition
to paintings, pictures and artifacts. MV halogen gives a good overall spread
of a quality functional light for general purpose lighting.
* Important Note: MV lamps are most commonly supplied with a GU10 cap. Quite
rare nowadays is the Dichroic version of the same lamp which has a GZ10 cap.
The main difference is that the GZ10 projects the majority of its heat backwards,
just like an LV lamp. Most of our MV fittings will accept both GU10 and GZ10
lamps, however we recommend, and will only supply the GU10 type. Most in our
industry expect that the GZ10 lamp will soon be phased out (remember the VHS
& Betamax situation? Well it's the same with GU10 and GZ10).
Special Circumstances to Consider
There are some applications where you should not use Mains Voltage downlighters.
Do not use them in a bathroom or wet area (except in the case of a dedicated
waterproof version such as our Mains Voltage GU10 shower-light). To go to
Bathroom Lighting Regulations go down the page
or click this link.
Likewise, there are some applications where you should not use Low Voltage
downlighters. The heat from an LV lamp is mainly projected backwards, so in
areas where the transformer would not have adequate 'breathing' space, i.e.
where roofing insulation or 'Rock Wool' would cover the unit, the lamp and
fitting would overheat. Transformers will overheat and may fail if laid under,
or on top of ceiling insulation. The heat from a MV lamp is projected forward,
thus making it most suitable for installation where insulation is present.
If the insulation is in an accessible loft space, you could consider using
Low Voltage lighting if you remove 3-4" of the insulation all the way
around the fitting and place the transformer on a beam, or piece of Plywood
placed no less than 12" from the fitting.
To go to Fire Risks associated with Recessed Lighting
go down the page or click this link.
Some Simple Facts:
Replacement Mains Voltage Halogen lamps can cost nearly twice that of their
Low Voltage brothers, yet can have half the expected lamp life! MV last 2000
to 2500 hours, LV 3000 to 5000 hours.
Both consume approximately the same amount of electricity, however the 50w Low Voltage Halogen lamp gives out approximately 20% more light than the 50w MV lamp.
MV lamps are available in 35 and 50w versions, LV in 20, 35 and 50w.
MV lamps are available in 25 and 40 degree beam spreads, LV in 12, 24, 38 and 60 degree.
A
transformer, like all electronic products, can occasionally fail (our IBL
transformers carry a full 10 year no quibble guarantee). MV lamps do not require
a transformer, this reduces initial purchase costs a little and cuts one item
out of the
scenario.
Both
LV and MV downlighters are dimmable, however, with MV you need to allow an
extra 25% capacity in your dimmer unit. A 400w dimmer can run only 6 x 50w
MV lamps. Although you also need to leave some extra capacity in your
dimmer with LV, 10% would normally suffice. Note: Always check your dimmer
unit is capable of running LV transformers.
LV
requires room to breath (air flow) above the ceiling, so may not be suitable
if space is limited, access is difficult or roofing insulation is present.
Remember - the heat from an LV lamp is mainly projected backward, MV mainly
forward.
So, Which is best? Points to consider...
Initial purchase cost - MV is cheaper.
Replacement lamp cost - LV is about half the cost, yet has approximately twice
the lamp life.
MV does not require a transformer, so there is less to install and less that
can go wrong in the future.
LV gives approximately 20% more light output.
MV lamps can be a little less awkward to change.
Our Advice?
Ultimately, you must decide based on the given facts. However, if pushed,
we always give the same reply. If possible use Mains Voltage downlighters
only when it is not possible to use Low Voltage. Either way, please always
employ a qualified electrician to do the work. If you are still in any doubt
about which way to go then call or email us for help or advice.
Just Arrived!
Compact Fluorescent GU10 fittings. A brand new concept in Mains Voltage downlighters.
They look exactly the same as LV or MV downlighters but have been specially
manufactured to take the new Low Energy Compact Fluorescent lamps. These are
available at 7watt, 9watts, 11watts and newly added an 11watt dimmerable lamp.
Now what will that do to the debate?
Copyright © 2007 Rowan Almond Limited
All
installations of bathroom lighting must comply to guidelines which are based
on a zonal concept similar to that used for the installation of lighting around
swimming pools.
Each zone is given an IP rating determined by the degree of risk of electric
shock.
Zone 0
This is the area inside the bath or shower and is rated at IPx7.
Zone 1
Refers to the area above the bath or shower up to a height of 2.25 metres
and carries a minimum rating of IPx4.
Zone 2
Covers an area 0.6 metres wide immediately next to, and all around zone 1,
plus the area over 2.25 metres high directly over the bath or shower. Wash
basins should be treated as zone 2. The minimum rating here is IPx4 Where
water jets are likely to be used for cleaning purposes in zones 1 and 2, the
rating is minimum IPx5.
Zone 3
Has no special requirements, unless water jets are likely to be used for cleaning
purposes.
Equipment installed outside zones 0,1,2 and 3 must be suitable for the conditions
most likely to prevail at that particular point.
When you fire rate a ceiling you measure the amount of time it can hold back a fire before it spreads to the floor above. But what happens when you cut a hole in a ceiling to fit recessed lighting?
According to Neil Perdell, a technical services manager, you immediately compromise that ceiling's fire rating and contravene a number of regulations.
Q
Why does a recessed light pose a fire risk?
A Most premises have fire-rated ceilings. This is the amount of time that
a ceiling can hold back the fire before it spreads to the floor above. A fairly
typical fire rating for a ceiling is 60 minutes. Of course, when you cut a
hole in a ceiling to fit recessed lighting, you immediately compromise that
ceiling's fire rating. The gaps within the light fitting will now be that
ceiling's weakest point. Flames, smoke and heat will find that gap and pour
through it, spreading the fire to the floor above.
Q
Won’t the light fitting fill the hole and restore the integrity of the
ceiling by itself?
A Almost certainly not. Conventional fluorescents and downlights are not designed
to fit seamlessly into a ceiling. No matter how good a job of installation
you make, there will still be a gap - and the fire rating of the ceiling will
still be severely compromised.
Q
Must a ceiling's fire integrity be restored after lighting is fitted, or is
it optional?
A The answer put simply is yes! The Building Regulations 1991 Approved Document
B Fire Safety 2000 Edition Section 11.2 (applicable in England and Wales)
says: 'If a fire separating element is to be effective, then every joint,
or imperfection of fit or opening to allow services to pass through the element,
should be adequately protected by sealing or fire-stopping so that the resistance
of the element is not impaired'.
The IEE Wiring Regulations 16th Edition BS 7671: 2001 Section 527-02-01 says:
'Where a wiring system passes through elements of building construction such
as floors, walls, roofs, ceilings, partitions or cavity barriers, the openings
remaining after the passage of the wiring system shall be sealed according
to the degree of fire resistance required of the element concerned (if any)’.
In other parts of the UK The Building Standards (Scotland) Regulations 1990,
Amendment 5, 1999, Technical Standard Part D or The Building Regulations (Northern
Ireland) 2000, Technical Booklet E would apply.
Q
How can a ceiling's fire rating be restored?
A Ideally, every luminaire in a recessed light fitting should be fitted with
a fire protection cover to BS476:
Pt.23.
Q
How can a fire protection cover restore a ceiling's fire rating?
A A fire protection cover prevents both flames and heat being transmitted
through the luminaire up into the ceiling void. Usually these covers have
a 60 minute rating, which will be in keeping with a typical ceiling fire rating,
although the best can last up to two hours.
Q
When is the best time to install a fire protection cover?
A Obviously, the best time to fit a fire protection cover is at the time the
lights are being installed, but they can also be retrofitted quite quickly
and economically.
Q
What kind of fire protection covers are on offer?
A Several types of fire protection covers are now available - the woven cloth
types and fully intumescent 'caps' which simply drop over the fitting. Both
can be highly effective in stopping fire, although the 'cap' design is seen
as being quicker and simpler to install both in new applications and in retrofits.
Being fully intumescent, it swells to over three times its thickness in the
event of a fire and is therefore particularly effective in minimising the
transmission of heat, as well as flames. Both types are readily available
from selected electrical wholesalers and models are available for use with
both downlights and fluorescent modules.
Q
Do fire protection covers put any extra strain on ceilings?
A No. They're very lightweight and suitable for use with all ceilings, including
plasterboard and suspended ceilings.
Q
Is it true that fire protection covers can also help with the acoustic performance
of a ceiling?
A Yes, but only some types. When recessed lighting is installed, it compromises
the acoustic rating of a ceiling in just the same way as it does the fire
rating. Sound bleeds through the gaps. UK Building Regulations Approved Document
E now requires that adequate steps are taken to prevent this transmission
of sound from one part of a dwelling to another. Good quality Fire Protection
Covers can solve the problem.
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