Light switch melted - Help!!

KiotiKevin · Jul 28, 2004

Hey guys,
I installed a set of flood lights on my ROPS on my Kioti CK25. 2 double 55w lights. I had a 50 amp toggle switch with a wire feed directly from the battery with an inline fuse (20amp) holder just before the switch. 220 watts of light for about 30 minutes - lights wouldn't shut off. Melted the inside of the switch! Should I reduce the fuse to 10amp ? Do I need a relay ? All and any suggestions welcome. Thanks
Kevin

Darren · Jul 28, 2004

Do I need a relay ? ... Yes!

Junkman · Jul 28, 2004

I would suggest that you use a relay and to put each light on its own fuse. Also, use a 10 or 12 gauge wire for each lamp. I would believe that you were just pulling too much amperage through that switch and that is why it melted. How its rating was determined is hard to say. It might have been rated for intermittent use. If my calculations are correct, you are drawing just a little less than 10 amps per light. I would use a 15 amp fuse for each fixture. How were the connections made at the switch? Many times, these type switches use spade connectors that just don't handle the amperage well enough. Also, the type of wire that you use is also important. A finely stranded wire will carry more current than a solid wire. How you make your connections is also important. I like to do a wire splice and then solder it to make connection such as these. Then I will either use heat shrink or electrical tape to complete the connection. In some instances, I would use both if I thought that water/moisture might be a problem.

BB_TX · Jul 29, 2004

Actually it is a little less than 10 amps (9.16) total for both lamps. (power in watts = volts x amps or amps = watts / volts). Obviously a switch with that rating should not have a problem with less than 10 amps. A lower rated fuse would not reduce the current. It would just blow if you went much below 10 amps. A relay is probably your best bet. But make sure you get a relay with contacts with a DC rating of more than 10 amps, preferably 20 amps. Some general purpose relays are only rated for AC.

Junkman · Jul 29, 2004

watts divided by volts = amps........
one fixtures with two 55 watt bulbs = 110 watts x 2 fixtures = 220 watts. 220 divided by 12 = 18.333 amps total or 9.16 amps per fixture. The tractor has two fixtures, so the total amperage draw on the switch was 18.333.

BB_TX · Jul 29, 2004

Oops!! /forums/images/graemlins/blush.gif I missed "double". You are correct.

boustany · Jul 29, 2004

Does seem unlikely a 50 amp switch would have cooked with that load. You sure of the switch rating? 50 amps is one honkin switch. I've seen 10 amps, but never 50!

Whats the part number/manufacturer of the switch?

Darren · Jul 29, 2004

That's why it's important to buy a relay that's rated for DC amperage. The 50 amp rating by itself is meaningless.

TWINKLE_TOES · Jul 29, 2004

Kevin,

Which ever way you go 'Switch or relay" the contacts need to be rated for the lamp load. A well specified contact is rated for pure resistive, inductive and incandescent lamp. Inductive loads derate the contacts by a factor of ~ 4 from the resistive rating and a factor of 10 for the lamp rating. A lamp will have an inrush current ~ 10 times it's running current. Your switch overheated in the carry only mode from contact heating, so I suspect it was a piece of junk from the get go.

Use 13.8 Volts to 14.2 volts for your current calculations, 12 volts would only occur with engine off and weak battery.