Im using some rope lighting as a lighting effect in the coving round my bedroom, problem is the rope light is longer than my permitere of room, and if i cut at the cut marks its too short, can i cut between the marks and wire that section to work still, can't be that hard surely? Don't i add a loop in or something?
cheers,
Al
Most of these type of lights have the lamps wired in series, so you'd also have to add a resistor equivalent to the lamps you have removed. Although each lamp might only be low voltage, the transformerless ones will have high voltages from 12-240v along the string.
Colin M
Hi Colin
many thanks for your reply, these lights are mains (uk 240v) powered, didn't think about the need for a resistor as well does that mean the short segment will shine brighter otherwise? Or if the resistance is too low i gather the voltage may be too high and blow the remaining lights?
Now i just need to know how i add my own loop and what resistance value i need i guess? I need to do it now as i've just cut 1ft off the end and that segment is now very much darker than the rest oops.
Hey Colin,
looks like i've got the answer, just an FYI
Take the wattage and work back from there. US (120v) Duralight is 18 bulbs per segment, 8.25w @120v (.06875a). The whole segment looks like a 1.8k resistor (roughly) so each bulb looks like a 100 ohm resistor. If your lights are still 8.25w per segment at 240v each bulb you cut out is 200 ohms or so. Add up the number you cut and use the appropriate resistor or as close as you can get bearing in mind the proportion of that 8w is resistor. It will be a fat one. If the resistance is low the lights will be brighter.
I have quite often seen the 'remaining' lighted section covered with black (opaque) insulating tape, or sufficiently large heat-shrink tubing. If it is necessary to have a light-coloured finish, heat-shrink tube usually has a matt surface which could be painted (?)
The excess length could be hidden behind the other end of the lighted section...
Don't forget that if a resistor is to be used with a cut string, make sure it's power rating is *more than* the lamps replaced or it will get dangerously hot or burn out.
Yes, that's it but make sure you have a sufficiently high rated resistor and it's not going to melt your plastic pipe.
Colin M Reply to group, or if email required, replace the abuse with broxie
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