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Old 12-03-2013, 08:36 PM
clayslandscape clayslandscape is offline
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12V vs. 14V

I have 4 50 watt fixtures. Would they be brighter hooked up to 14V instead of 12V?
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Old 12-03-2013, 08:47 PM
Alan B Alan B is offline
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If they are halogen/incandescent then yes they will be brighter but don't do it.

12v lamps are meant to be run between 10.5-12 volts. Once you go above 12volts their life span will drop dramatically. At 13 volts the life span will be ~50% and 14 volts ~25%. Additionally they will be outside their designed safety voltage range. (if below 10.5 volts they will not be burning hot enough and can give off a black soot that reduces life span as well).

If they are 50v equivalent LEDs then the answer is no they will not be brighter. LEDs use constant current drivers. LEDs have a much wider operating range which varies depending on driver design. The range can be as big as 6-30 volts but is usually around 9 volts-18 volts.

Cheers!
Alan
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  #3  
Old 12-03-2013, 09:10 PM
clayslandscape clayslandscape is offline
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Thanks Alan! Why do they make transformers that have the 14V option then?
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  #4  
Old 12-03-2013, 09:35 PM
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Classic Lighting Classic Lighting is offline
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The 14 volt tap on a transformer compensates for voltage drop in the wire. Resistance in copper wire reduces voltage until it gets to the termination point.
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Old 12-04-2013, 08:25 AM
Alan B Alan B is offline
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Classic Lighting is right on. To clarify, the goal for halogen/incandescent is to get 10.5-12 volts at the fixture. As your cable run gets longer and/or you add more fixtures (load) onto the cable, the voltage drops. So if you start at 12 volts and have a long wire run, the voltage might only be say 9 volts at the end of the run. The higher voltage taps on the transformer (such as the 14 volt tap) enable you to boast the starting voltage so that you can get your desired 10.5-12 v even on longer runs or runs with more fixtures.

This is all old school now. If you switch to LEDs it's a different ballgame that is much easier. LEDs can operate properly anywhere from 9-15 volts (for the most part) so you have more flexibility. Secondly they draw ~5X less power so the load is so much less-- that means there is less voltage drop to begin with. With LEDs the layout is much less critical. You can generally just hook up to the 12 volt tap (or 15 volt tap if you have longer runs with lots of fixtures) and daisy chain all the fixtures on the same run. It doesnt matter whether the voltage at the fixture is 9 volts or 15 volts-- the LED will perform the same output. Go LED its easier, faster, less maintenance, 80% more efficient.
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Old 02-23-2014, 11:00 AM
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emby emby is offline
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Sorry to put this back at the top but thought it was important to do so.
So far from me reading through the threads I keep reading responses that lead everybody to believe that you can simply use less wire and daisy chain all these fixtures with LED lamps. This is not correct. All these halogen fixtures clearly have Max. Wattage UL and CSA stickers inside of them. Most are 50 watt max. You must continue to use the old wiring methods if you use these types of fixtures. It's the same old scenario when you were lamping with halogen. If you used these same type fixtures but only used 10 watt lamps did you start changing the wiring methods? No. How is it different using LED lamps? Integrated LED fixtures are totally different as there max. wattage/va cannot change. Yes, you can still use smaller transformers but again your wiring methods remain the same as if your using halogen. The only other way I have seen an a exception is to ask the manufacturer to change those UL/CSA max. wattage stickers. I'm surprised that the inspectors have not been asking for this.
Again sorry to be placing this at the top.

Ken




Quote:
Originally Posted by Gr1ffin View Post
Classic Lighting is right on. To clarify, the goal for halogen/incandescent is to get 10.5-12 volts at the fixture. As your cable run gets longer and/or you add more fixtures (load) onto the cable, the voltage drops. So if you start at 12 volts and have a long wire run, the voltage might only be say 9 volts at the end of the run. The higher voltage taps on the transformer (such as the 14 volt tap) enable you to boast the starting voltage so that you can get your desired 10.5-12 v even on longer runs or runs with more fixtures.

This is all old school now. If you switch to LEDs it's a different ballgame that is much easier. LEDs can operate properly anywhere from 9-15 volts (for the most part) so you have more flexibility. Secondly they draw ~5X less power so the load is so much less-- that means there is less voltage drop to begin with. With LEDs the layout is much less critical. You can generally just hook up to the 12 volt tap (or 15 volt tap if you have longer runs with lots of fixtures) and daisy chain all the fixtures on the same run. It doesnt matter whether the voltage at the fixture is 9 volts or 15 volts-- the LED will perform the same output. Go LED its easier, faster, less maintenance, 80% more efficient.
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Last edited by emby; 02-23-2014 at 11:04 AM.
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Old 02-23-2014, 04:54 PM
GreenLight GreenLight is offline
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Quote:
Originally Posted by emby View Post
Sorry to put this back at the top but thought it was important to do so.
So far from me reading through the threads I keep reading responses that lead everybody to believe that you can simply use less wire and daisy chain all these fixtures with LED lamps. This is not correct. All these halogen fixtures clearly have Max. Wattage UL and CSA stickers inside of them. Most are 50 watt max. You must continue to use the old wiring methods if you use these types of fixtures. It's the same old scenario when you were lamping with halogen. If you used these same type fixtures but only used 10 watt lamps did you start changing the wiring methods? No. How is it different using LED lamps? Integrated LED fixtures are totally different as there max. wattage/va cannot change. Yes, you can still use smaller transformers but again your wiring methods remain the same as if your using halogen. The only other way I have seen an a exception is to ask the manufacturer to change those UL/CSA max. wattage stickers. I'm surprised that the inspectors have not been asking for this.
Again sorry to be placing this at the top.

Ken


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I understand what you are saying (at least I think I do for the most part) and im not really putting up an argument, just some questions. I do understand your point about what the fixture "max rating" is and how you would build to correlate to this.

I suppose my question is this. As you said, most compact uplights are rated at 50 Watt Max (I have seen some at 75 watt max). By that rating and my understanding of the requirements you are describing, wouldn't that mean that the max fixtures you could put on a 12-2 wire (whether it be hub, Tee, daisy chain, etc) would be 3? On 10-2 you would be limited to 5 of these style fixtures per run. 8-2 would be about 5 as well. Staying within these same parameters of designing based on max fixture rating wouldn't the maximum number of fixtures of this style per 300 Watt Common be 6? So let's say you are running 6 x 20 watt halogen lamps in these fixtures. By the logic im gathering from what you have stated, that would require at least 2 home runs no matter what size the wire is. It would also be at the maximum transformer rating of 300 watts per common tap. Am I misunderstanding?
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  #8  
Old 02-24-2014, 08:54 AM
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emby emby is offline
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Yes by analyzing your scenario you are correct somewhat. If the fixtures are rated for 50 watt max and you are using 12/2 then four fixture would be the max.
The reason is if the home owner or who ever changes these lamps to the highest max. rating of the fixture then that would most certainly cause issues with any other wiring methods. Basically 12/2 is rated for 20 amps. By looking at the max. rating sticker on the fixtures you choose, don't exceed the 20 amps on that particular homerun. Now as far as the the transformer goes... If the wiring methods are correct and the homeowner does change the lamps then the secondary breaker in the transformer will trip and the wire will not burn and start a fire. Those secondary 25 amp breakers protect your wire from burning.
Hope this help clarify.
Ken






=GreenLight;4967025]I understand what you are saying (at least I think I do for the most part) and im not really putting up an argument, just some questions. I do understand your point about what the fixture "max rating" is and how you would build to correlate to this.

I suppose my question is this. As you said, most compact uplights are rated at 50 Watt Max (I have seen some at 75 watt max). By that rating and my understanding of the requirements you are describing, wouldn't that mean that the max fixtures you could put on a 12-2 wire (whether it be hub, Tee, daisy chain, etc) would be 3? On 10-2 you would be limited to 5 of these style fixtures per run. 8-2 would be about 5 as well. Staying within these same parameters of designing based on max fixture rating wouldn't the maximum number of fixtures of this style per 300 Watt Common be 6? So let's say you are running 6 x 20 watt halogen lamps in these fixtures. By the logic im gathering from what you have stated, that would require at least 2 home runs no matter what size the wire is. It would also be at the maximum transformer rating of 300 watts per common tap. Am I misunderstanding?[/QUOTE]
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