Can somebody please clarify my assumptions/reasoning is correct.
I am intending on replacing my existing ceiling light(s) in the hallway with recessed downlights GU10/55W
I plan on using 2 lights downstairs and 3 upstairs - the circuits are on two seperate rings. Fused with what reads as a 5 amp fuse.
So upstairs I have four rooms each with 60watt bulbs and the 3 new hall lights giving a total load of (4 * 60watts) + (3 * 55 watts) equivalent to ... 405watts.
Upstairs == 405/240 = 1.68 amps...
From the wiki //www.diynot.com/pages/el/el004.php I calculate i can get away with using 1mm/sq cable. However the current wiring all seems to be 1.5mm/sq (i have some 1mm/sq wire and comparing it to the copper in my house, the house lighting circuit is definitely thicker)
Why would the existing wiring use greater than 1mm/sq for the lighting - everything else in my house has been done on the extreme cheap so why would they have used cable they may not have needed which costs more.
I am obviously missing something in my naive calculations. I thought about voltage drop but my house is so small i doubt the difference.
Using http://www.tlc-direct.co.uk/Technic...230&length=30&submit=Calculate+Min+Cable+Size with the following parameters again gave me 1mm/sq
Cable Type Twin/Earth
Application Lighting
Circuit Type
Ambient Temperature 30°C
Number of Circuits 3
Power 405 Watts
Voltage 240 Volts
Length 30 metres
Required Cable Size 1 mm
Voltage Drop 1.55 Volts.
Percentage Drop 0.67%
Current Load 1.00 Amps
Max Cable Load* 9.10 Amps
Please can somebody help me .. or give my some pointers.
Thanks in advance for reading this far
I am intending on replacing my existing ceiling light(s) in the hallway with recessed downlights GU10/55W
I plan on using 2 lights downstairs and 3 upstairs - the circuits are on two seperate rings. Fused with what reads as a 5 amp fuse.
So upstairs I have four rooms each with 60watt bulbs and the 3 new hall lights giving a total load of (4 * 60watts) + (3 * 55 watts) equivalent to ... 405watts.
Upstairs == 405/240 = 1.68 amps...
From the wiki //www.diynot.com/pages/el/el004.php I calculate i can get away with using 1mm/sq cable. However the current wiring all seems to be 1.5mm/sq (i have some 1mm/sq wire and comparing it to the copper in my house, the house lighting circuit is definitely thicker)
Why would the existing wiring use greater than 1mm/sq for the lighting - everything else in my house has been done on the extreme cheap so why would they have used cable they may not have needed which costs more.
I am obviously missing something in my naive calculations. I thought about voltage drop but my house is so small i doubt the difference.
Using http://www.tlc-direct.co.uk/Technic...230&length=30&submit=Calculate+Min+Cable+Size with the following parameters again gave me 1mm/sq
Cable Type Twin/Earth
Application Lighting
Circuit Type
Ambient Temperature 30°C
Number of Circuits 3
Power 405 Watts
Voltage 240 Volts
Length 30 metres
Required Cable Size 1 mm
Voltage Drop 1.55 Volts.
Percentage Drop 0.67%
Current Load 1.00 Amps
Max Cable Load* 9.10 Amps
Please can somebody help me .. or give my some pointers.
Thanks in advance for reading this far