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Discussion in 'Landscape Lighting' started by East Coast Lawn Choppers, Aug 21, 2009.
Hire a pro!
I thought this site was to ask questions and get help. By the way did you read the first part of the whole thing ??? I'm correcting an electricians job...
I'm trying to go back to my early courses in electronics to figure it out. Kind of forget the basics after working with plc programming and working on lasers. Don't think exciting electrons and emitting photons will help here...
It is funny... we do patios and two people asked us to do lighting. I left an electrician (isn't he the pro?) do all except I ran the conduit under the patio and ran the wires thru the walls. Now "me" the stupid person is trying to correct a "pro's" problem which he says is normal for bulbs to only last a year when they run the lights for 4 hours every single night... I think they should last longer.
P.S. I have a degree in electronics from 20 years ago, but after getting another degree in electro-mechanical (forced to by work that closed right after I finished the degree) it's hard to retain everything. So I am trying to get a little refresher and some help...
Sorry, Its not personal.
Well Mr.East Coast Lawn Choppers,
Where do I start...I always have this rule in the back of my mind and that when it comes to safety you remove the hazard from the people or you remove the people from the hazard. Esentially where I am going with this is if you have bulbs melting thats not a good thing and you already know that. So rather than spend all your time doing OHMS law and trying to problem solve remove the hazard from the people and install a professional landscape lighting system that is going to make the customer safe and happy. Its really a no brainer.
Personally I feel the customer should be made aware of the hazard and to unplug the transformer until someone more qualified can come in and resolve the issues.
I appreciate that you are looking for advice and help with this matter but when it comes to safety I think that you will find everybody repeating what I have just written.
Ok update... I went over early to check it out before it starts to rain again... Here is what I found...
There are not 4 12V 35W quartz halogen lights on one circuit. There are actually 3 on one string and one on seperate circuit all by itself... low and behold that is the one that melted the coating on the wires.
The way I'm figuring the 35W 12V bulb should be a 4.114 ohm load so at 12V it draws 35W's so if the voltage goes up to 12.5V it would draw 38W's
I'm going to put a new fixture on and check the voltage at the fixture with a new bulb in. At that time I will check the input voltage also. When I checked it the other day it was in the heat with air conditioners running. Input voltage might have been a little low and I got 12V at the transformer, if at night time the input goes higher maybe the output voltage will be higher. ,,,, Before someone says input voltage won't change much... Our house I've seen 120V as low as in the low 100's to even high 90's on a hot day around 5:00pm air conditioners running and people using ovens etc... and we have a 200 amp service that is only 3 yrs. old. It is what we get supplied by the street...
When I find more I'll post it...
I guess I need a transformer that has a 11V tap... shame they paid a fortune for a profesional one that won't do what they want...
This could simply be a matter of not enough wire between the transformer and the lamps. As a rule of thumb here, I always ensure that there is at least 15' of wire between the transformer and the first fixture (unless I have an 11V tap to work with).
'cheap' lamps and 12V lamps in general do not like to be over-volted. even slightly over 12V will drastically reduce the lamp life of the best 12v lamps. You could simply have a situation where the lamps are receiving more than 12v at during certain operating conditions.
The advice you have received here is good. Adjust the amount of wire you have between the transformer and the lamps so that they are running at consitant low 11's, use quality name brand lamps, and you should be in the clear.
Thanks Integra, I already replaced the small bulbs and I used Sylvania's in them. The one wire I have figured is only about 3' long with only one 35W bulb on it so that one needs to be lengthened. I pulled apart the other three that are identical to the one that melted the wiring and they look OK. I still think I'm going to drop the bulbs down a notch in those. They are 35W and I found 10W and 20W bulbs. I'll probably put the 20W's in to see if they run a little cooler. On Monday when I get out there and get everything back up and running I'll do voltage checks out at the bulbs and try to get it down to 11V's I'll lengthen the wire on that one to 20' or so and work from there. Beings it only has one 35W on it should I use 12 ga wire for the extra length to try to drop it more ?
Thanks again for the help.
A. Loose the sig...... Way way to long
B. Do you have 35 watt lamps in this style fixture
*If so there might be the problem.*
C. 10g. wire for 35 watts 15 feet away is still overkill.
to get the voltage to drop try and run 16g. All the way back to the trans. Just watch your amp load on the length of run...... I put 35watts on 50ft leads into trees all the time. Never a problem.
D. If that doesnt work Nightscaping use to sell a little box that took it down to 11.6 I think.... Im sure James could chime in on that.
I believe Rockscapes sells a voltage regulation device. Never tried it, just another thing to fail. Kichler also sells a 75W voltage regulator device but it is massive and is basically a big potted transformer that you (might try to)bury. Not too cheap either.