12v
- the benefits of a low voltage system are;
!
12 volts is inherently safe.
!
Smaller, more discrete lights, and a wider choice of quality lights
!
Easy installation of cables in borders, so spotlights can be moved
!
A wider range of halogen lamp wattage and beam angles
!
A wider range of compact led lights, especially deck lights
!
12v halogen lamps are brighter & whiter and last longer than 240v
equivalents (but 240v halogen lamps are good for patios)
!
Powersaver
halogen lamps are only available for 12v operation
!
Transformers are not difficult to hide and 12v systems can be cheaper
to install as well as more flexible in use and easier to maintain
!
12v systems are more fault tolerant than 240v - less spurious tripping!
240v
- the main advantages of 240 volt installations are;
!
No need to use transformers
!
Easier installation of wall spotlights on house walls
!
Fewer voltage drop problems in 240 volt cables than 12v
!
Low energy, long life compact fluorescent lamps are 240 volt
But - nearly all 240v cables must be armoured or protected against
damage: only the last 2m can be flexible cable, which means
more junction boxes and less flexibility. Systems comprising 240v
lights are more prone to tripping circuit breakers when damp or
lamps blow
What length of cable can I use from the transformer to a light?
“Cable voltage drop” occurs in all electric cables, but in a 12 volt garden lighting system care
must be taken to limit this to avoid loss of light output resulting from voltage reduction at the
lamp. Some manufacturers recommend a maximum of 1 volt drop, but this would result in a loss
of 30% of the rated light output of a halogen lamp - a 50 watt lamp would only give 35 watts worth
of light (see graph right). The loss of voltage is higher the longer the cable run and the higher the
lamp wattage. To limit loss of light output, keep cable voltage drop to under 5% (0.6 volt in a 12
volt system) by sticking to shorter cable runs wherever possible. The table below gives the
maximum length of cable run for typical garden lighting wiring requirements for halogen lamps -
stick to these cable lengths to get full brightness from your system.
Recommended maximum cab le run for 12v l.e.d. lights (Assumes maximum 8% voltage drop i.e. 1 volt)
Lights mainly at end of cable
Total l.e.d. wattage (added together)
2.4
3.6
4.8
6
8
10
12
15
20
30
40
50
1.5mm
2
Cable run (metres)
172
115
86
69
51
41
34
27
20.6
13.7
10.3
8.2
2.5mm
2
Cable run (metres)
258
172
129
103
76
61
51
40
31
20.5
15.5
12.3
Lights spaced evenly along cable
Total l.e.d. wattage (added together)
2.4
3.6
4.8
6
8
10
12
15
20
30
40
50
1.5mm
2
Cable run (metres)
258
172
129
103
76
61
51
40
31
20.5
15.5
12.3
2.5mm
2
Cable run (metres)
387
258
193
155
114
91
76
60
46
31
23
18.4
Can I run longer cables to l.e.d. lights (light emitting diodes)?
Yes
.
l.e.d.’s consume a lot less power than incandescent lamps and are generally less sensitive to small voltage reductions, so cable runs can
also be a lot longer. But do remember that groups of high power led lights such as MR16 6w or AR111 7w led modules collectively take quite a lot
of power, so it is often best to follow guidance for an equivalent wattage of halogen lights for these models. The table below gives suggested
maximum cable runs for 12v ac constant voltage installation. 1.5
ground burial low voltage cable will be adequate for most l.e.d.
installations and is available in 25m (T9919) and 50m (T9918) packs. Stick to ground burial cable even under decks as there is no such thing as
a dry location in most gardens and this tough rubber cable is resistant to garden chemicals, ultraviolet light and cleaning fluids as well as damp.
2
mm
led products in this catalogue are for parallel wiring from
a
12v constant voltage supply, not constant current supply. Use of an incorrect power supply can
damage led lights and invalidate the warranty. Wire wound (magnetic) surface-mount or ground burial transformers or ground burial toroidal transformer kits
are recommended: do not use electronic transformers with 12v led lights as interaction of the two products along long cables can produce unstable lighting
Lamp watt s
20
35
50
75
20
20
35
20
20
35
35
Number of lamps
1
1
1
1
2
3
2
2
3
2
3
1.5mm
2
cable run (metres)
13.2
7.3
5.3
3.5
6.6
4.4
3.7
8.6
6.6
5
3.7
2.5mm
2
cable run (metres)
20
11
8
5.3
10
6.7
5.5
13
10
7.6
5.5
4mm
2
cable run (metres)
32
18
13
8.4
16
11
8.7
21
16
12
8.7
* lights of 50 wa tts or m ore s hould be individually w ired from the tra nsform er * * lights eq ually spa ced a long the ca ble
Recommended maximum cable run (metres) for 12v halogen lights (Assumes maximum 5% voltage drop i.e. 0.6 volt)
1 light at end of c able*
lights at end of c able
lights spaced along cable**
Symbols with each group of products help you to identify
attributes such as voltage & low energy options
Requires supply from 12v transformer or dc power supply
Suitable for direct connection to 240v mains supply cables
Maximum lamp rating in watts which may be used in
Low energy versions for metal halide discharge lamps
Low energy versions for long life compact fluorescent lamp
Contains light emitting diodes/may use an led module
Ingress protection (IP) rating provides a measure of how
dust/insect proof and weatherproof lights are:
First digit -
Protection against solids
2
4
Resistance to foreign bodies down to 1mm
5
Generally proof against contact and dust
6
Completely dustproof
Second digit -
Protection against liquids
4
Splashproof
5
Hose-proof
6
Pressure hose proof
7
Protection against limited immersion in water
8
Continuous submersion in water, usually to 2 metres
12v
75w
240v
IP68
CFL
LED
MH
W h i l e e v e r y c a r e h a s b e e n t a k e n w i t h t h e c o n t e n t s o f t h i s p u b l i c a t i o n , w e a c c e p t n o r e s p o n s i b i l i t y f o r a n y i n a c c u r a c i e s a n d r e s e r v e t h e r i g h t t o c h a n g e
specifications without notice in order to always ensure you are receiving a superior product. Ensure installation and maintenance are properly undertaken to
obtain optimum product performance, efficiency and durability from these products. E & O E. Light fittings can become hot in use: exercise appropriate precautions
.
Key to Symbols
12v or 240v - which is best?
100
80
60
40
20
0
50 60 70 80 90 100
% voltage
%
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