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Q.
How many
lights can I power from one transformer?
A.
In fact, transformers are available
in a wide range of wattage ratings, so we need to look at the question
the other way around: "what size of transformer do I need to
power the group of lights required"? This is simply a matter
of multiplying the wattage and numbers of the lamps used in the luminaires
(garden lighting fittings) to be connected
to the transformer.
For example 6 light
fittings at 20 watts = 120 watts in total. Therefore a 150 watt(va)
transformer is required.
In most cases we need
to consider some spare capacity within the transformer rating so that
we have scope to increase some lamp wattages as plants grow, or to
allow for some flexibility in adding a luminaire in the future. Make
sure the transformer is at least 60% loaded - don't wire one low power
light to a big transformer in the expectation of installing lots of
other lights later - all you will do is over-volt the small lamp and
shorten the bulbs life !
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Q. What
is a transformer and why do I need one?
A.
Most good garden
lighting works at 12 volts, so you need to locate transformers in
the garden or nearest building and use flexible low voltage cable
from the transformer to the lights themselves. A transformer is an
electrical or electronic device which changes voltage from one level
to another; in lighting this is usually from 240 volts to 12 volts,
which is the voltage at which many garden lighting products
work. From the transformer to the luminaries (light fittings), the
low voltage cable typically runs under mulch and over garden structures.
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Q.
Can the transformer be mounted outside?
A. Yes. The standard range of exterior
garden lighting transformers are housed
in black weatherproof IP rated boxes, normally to be mounted on a
wall or post where they will be hidden behind planting and landscape
features, or in manholes, under decking, and in outbuildings. Special
ground burial types are available for locations where it would be
difficult to site a transformer within a reasonable distance of the
garden lighting fitting.
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Q.
How
far can I run a low voltage cable from a transformer to a garden lighting
product?
A. Cable loses voltage according to its
length and the number & power of lights you connect to it, so
keep low voltage cable runs as short as possible to optimise the performance
of your garden lighting products. To
minimise cable voltage drop to the luminaires, identify groups
of lights which can be supplied from one central transformer. Check
that the transformer location is within the length of the low voltage
cable permitted (see voltage drop chart: In many rear gardens, a typical
configuration may require one transformer on each side of the garden
and perhaps one transformer to cover features at the far end of the
garden. The 240 volt supply to the transformers should be via a steel
wire armoured cable incorporating a separate core for earthing.
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Q.
How
many low voltage garden lighting products can I connect to one cable?
A. Adding too many lights onto one cable
increases cable voltage drop and reduces the distance the cable can
be run before the loss of voltage dims the garden
lighting products too much. See the question above for the
solution to this.
As a rule of thumb, wire a maximum of three 20 watt lights equally
spaced along a 10 metre ground burial cable and wire higher power
lights individually from the transformer position to allow flexibility
in positioning the garden lighting fitting
in the future as planting grows or the garden changes.
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Q.
Do lights get hot?
A. Yes, but some get hotter than others.
For example, recessed garden lighting
products in decking and paving will get particularly hot with a 50
watt lamp fitted, so don't use these in unshielded areas where people
or pets might stand on them; if in doubt use a recessed light with
a protective grid over the lens or stick to 20 watt lamps for a cooler
lens temperature. Likewise, spotlights with 50watt lamps and upwards
get particularly hot when they've been on for a little while; you
should wear a good pair of insulating gloves (such as thick gardening
gloves) to protect your hands when adjusting spotlights.
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Q.
Can
I install any garden lighting products myself?
A. Low voltage garden
lighting products are easy enough to connect but the transformer
connection and installation of any other mains voltage lights or equipment
can lead to dangerous situations if not done correctly. The equipment
we supply is used by professionals to create lighting
effects beyond the capabilities of most DIY equipment. You should
employ a qualified electrician to undertake any exterior electrical
installation, or to test an existing system.
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Q.
How do I know what lamp beam to buy?
A. The principal beam angles for low voltage
reflector lamps are 12, 24, 36 and 60 degrees. Sometimes you will
want a small pool of light from a narrow beam to accent a feature
without lighting the surroundings; other subjects will require the
widest coverage available, such as a 60 degree beam. For example,
a 60 degree beam will provide wide coverage from a pergola beam only
1.5 metres above a table below, but if you are uplighting a slender
tree the coverage of a 600 beam will be wasted in the night
sky; a narrower beam ,10 degree, will "fit" the shape of
the tree more closely. If in doubt, be prepared to experiment a bit
by changing the lamp to compare the different garden
lighting effects.
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Q.
How can I fit recessed lights in decking?
A. There are several types of garden
lighting products which can be used;
One
of the most popular is the Hunza copper path light PTL; it eventually
weathers to a soft verdidris colour which tones well with the natural
colour of wood and stone.
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Q.
Do copper lights go green after a short while?
A.
No. It usually takes a long time for copper garden
lighting products to acquire a verdigris patina. This is a
chemical process which takes time unless the copper is subjected to
chemical catalysts such as polluted water or garden sprays. Copper
lights will usually acquire a natural-looking mottled brown finish
after just a few weeks outside. If you want the verdigris finish,
spray two or three times a week with a copper fungicide such as Benlate
to hasten the process. If your copper lights turn green and you prefer
the natural brown weathered appearance, clean them with bathroom limescale
remover and let them weather again naturally.
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