Souster Posted June 13, 2010 Share Posted June 13, 2010 Hi, Today i wired up my 55w worklamp using landymanluke`s diagram which i found fantastic. I used a 30amp relay and a 13amp fuse between the battery and pole 30 on the relay. I havent got a switch at the moment, so i was just touching a piece of wire to the +ve on the battery from pole 85 on the relay (just so i could test i had wired it up correctly. The worklamp worked perfectly for a few minutes. But when i felt the lens on the lamp it felt very hot... soon after the bulb blew. Ive used 25amp thin wall cable and the correct fittings. My question is what is causing the bulb to blow?? many thanks, Josh Quote Link to comment Share on other sites More sharing options...
oakesy Posted June 13, 2010 Share Posted June 13, 2010 The lens will be hot because it will increase the light and heat created. As for the duration of the bulb could be greasy fingers dodgy bulb bad earthing or to much power for the element. Quote Link to comment Share on other sites More sharing options...
Souster Posted June 13, 2010 Author Share Posted June 13, 2010 thankyou for the quick reply. So its nothing to do with having a relay rated at 30amps for one lamp then?? Quote Link to comment Share on other sites More sharing options...
crwoody Posted June 13, 2010 Share Posted June 13, 2010 The "30 amp" rating for the relay simply means the current carrying capacity of the contact, so long as it's higher than the actual load you are switching it's no problem, it certainly wont increase the voltage to the lamp which is about the only thing that could make it blow - apart from a faulty bulb etc as Oaksey says. It's not a 6 volt bulb is it? (like a battery hand lamp one.) Quote Link to comment Share on other sites More sharing options...
Souster Posted June 13, 2010 Author Share Posted June 13, 2010 thanks alot guys. Must of been a dodgy bulb then. It was a H3 55w bulb in a ring work lamp. Quote Link to comment Share on other sites More sharing options...
oakesy Posted June 13, 2010 Share Posted June 13, 2010 Check your volts first to see if there is too much . A relay only works with switches. To blow bulbs or melt wires are by low watt usage or low grade wires. If anything the fuse should blow first before the bulb. Quote Link to comment Share on other sites More sharing options...
hobson Posted June 13, 2010 Share Posted June 13, 2010 Be careful touching bulbs too, halogen doesn't like greasy fingers, it's acidic to them.... Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted June 13, 2010 Share Posted June 13, 2010 My guess is touching the bulb with dirty fingers contaminated it, the bulb itself will tolerate much grease/oil/muck on it. That, or it was just a poor bulb. But, it's worth checking your battery/alternator voltage. If the regulator is faulty you could have more than 14.4 volts, but this would affect all bulbs, not just the one you've fitted. Quote Link to comment Share on other sites More sharing options...
M&S Posted June 13, 2010 Share Posted June 13, 2010 As it's only drawing 6.6A you could have gone straight through a carling type switch rated at 8A (fused obviously) Quote Link to comment Share on other sites More sharing options...
mickeyw Posted June 15, 2010 Share Posted June 15, 2010 If you find you have touched the glass section of the bulb by accident, clean it with a piece of paper towel and methylated spirit. This will remove finger print grease Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 15, 2010 Share Posted June 15, 2010 As it's only drawing 6.6A you could have gone straight through a carling type switch rated at 8A (fused obviously) And hopefully fused with a 7.5 or 10A blade fuse, I'm a bit concerned where you got a 13A fuse from as it suggests you've managed to wire a mains plug fuse into your car Oaksey - any chance of having that post in English? Quote Link to comment Share on other sites More sharing options...
Souster Posted June 15, 2010 Author Share Posted June 15, 2010 thanks for your help. The reason why i used a 13amp fuse was because i used a inline fuse from the battery to the relay. I hadnt got any standard 10 amp fuses so i used a 13 temporarily. Quote Link to comment Share on other sites More sharing options...
matthew74 Posted June 15, 2010 Share Posted June 15, 2010 Just a few little queries on this subject while it's up and running. Firstly the fuse size. W = VA so 55w/12v = 4.6 amps? Also do you need some sort of indication on the dash that the work light is on like an illuminated switch or an LED light for it to pass the MOT? Quote Link to comment Share on other sites More sharing options...
M&S Posted June 15, 2010 Share Posted June 15, 2010 Just a few little queries on this subject while it's up and running. Firstly the fuse size. W = VA so 55w/12v = 4.6 amps? Also do you need some sort of indication on the dash that the work light is on like an illuminated switch or an LED light for it to pass the MOT? You are correct, typo on my half (sorry). I use a 5A fuse. Mine has passed two MOT's now, and I don't have an illuminated switch or dash indication. I'm not saying it's correct as I don't know, but I do know that two test centres over two years have never checked mine. I doubt they'd even notice the switch Quote Link to comment Share on other sites More sharing options...
Souster Posted June 15, 2010 Author Share Posted June 15, 2010 right folks, thanks for your replys its cleared things up for me... I will now use a 5 Amp fuse from now on then. To be honest, the reason why i ran it through a relay was because originally i was going to have two rear work lamps on the back. Switched on by a carling switch. But i then changed my mind and stuck with one still using the carling switch. Would i be better, getting rid of that relay (for the worklamp) and save it for the 4x55w spotlights i plan to have on a lightbar at the front. Which will be switched on via the main beam, but have a carling override switch for legal reasons. Thanks alot, Josh Quote Link to comment Share on other sites More sharing options...
M&S Posted June 15, 2010 Share Posted June 15, 2010 You could do/may as well do if you want to use the relay elsewhere. Save buying another one Quote Link to comment Share on other sites More sharing options...
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