Multi-tap?

[MuirView Design]

We are planning on installing 15-17 integral lights on the patio we are building & 2 uplights. I'm figuring on a 300W transformer and running 12/2 wire. It's about 45' of run to the furthest light. Is 300W going to be enough? Is 12/2 the gauge you would recommend?

I'm also curious if you would recommend I use a multi tap transformer for better regulation? I'm assuming doing more of a hub system would be preferable?

This is only my second time doing lighting, so I'm still a little green in this area. Another question I have would be about conduit. What size do you guys generally use? Do you always bury your wire under the modified when crossing the patio?

Thanks!

[Mbella]

Adam, do you know the wattage of the bulbs? That transformer seems a little underpowered for the system.

[GreenMonster]

rule of thumb is to use only 80% of the transformer's capability. integral are only 10 or 12 watts, aren't they? If so, 300 should be plenty.... unless they're 20 watts.....

[MuirView Design]

Integral bulbs are no bigger than 12 watts. What about the wire and multitap...any suggestions?

[GreenMonster]

Integral bulbs are no bigger than 12 watts. What about the wire and multitap...any suggestions?

Adam, 12-2 sounds fine. your runs don't sound long. I always use multi-tap, much more flexibility. If you end up sticking to 5 per hub, I would bet you'd end up using mostly 11 v taps.

[MuirView Design]

Thanks Mark! How bout the conduit? Do you always bury the wire in conduit in the base and pop up in the wall? What size conduit do you recommend?

[NCSULandscaper]

use this calculator to figure which taps to use

http://www.cast-lighting.com/volt-calc.html

[Mbella]

Nice calculator Matt. In addition, test the lights when you're done and adjust as needed.

[MuirView Design]

use this calculator to figure which taps to use

http://www.cast-lighting.com/volt-calc.html


Thanks bro!!! This will be a huge help!

[GreenMonster]

i rather run the conduit on the out side of the patio if you can. also, you don't have to have the wire in conduit, but you should if it's under the base, in case you need to work on it in the future

[MuirView Design]

i rather run the conduit on the out side of the patio if you can. also, you don't have to have the wire in conduit, but you should if it's under the base, in case you need to work on it in the future

Would another option be running it on top of the base and under the sand? Or is this a big no no? A lot of the lights will be on the steps on the inside of the patio. I thought running them on the outside would be weaken the output...but maybe not. Here's one of the renders I did of the lighting setup. We are adding a few more to the back of the seat wall and the sides of the pillars.

Does anyone use a general rule for pricing integral light installation? (i.e. $x / per light)

http://img222.imageshack.us/img222/1458/final1md6.jpg (http://imageshack.us)
http://img222.imageshack.us/img222/final1md6.jpg/1/w1614.png (http://g.imageshack.us/img222/final1md6.jpg/1/)

[ZX12R]

We are planning on installing 15-17 integral lights on the patio we are building & 2 up lights. I'm figuring on a 300W transformer and running 12/2 wire. It's about 45' of run to the furthest light. Is 300W going to be enough? Is 12/2 the gauge you would recommend?

I'm also curious if you would recommend I use a multi tap transformer for better regulation? I'm assuming doing more of a hub system would be preferable?

This is only my second time doing lighting, so I'm still a little green in this area. Another question I have would be about conduit. What size do you guys generally use? Do you always bury your wire under the modified when crossing the patio?


Adam,assuming that 17 integral lights are 12 watts apiece and the two up-lights you plan to use are 20 watts each,you are barley at the recommended ratings of a 300 watt transformer. You will be fine,just be sure you are not going to add lights later. If you are not sure spend an extra $100 or so and get a 600 watt transformer.

In reference to the 12-2 wire,with your longest run at 45',you will be fine. Keep in mind that this wire will generate heat,so,do not overload it. If this is a concern,use 10-2,which is a good idea anyway. I use it on every run,even if its 20' away from the transformer.

A hub is surely the way to go.Your lighting system will be very efficient and all your lights on that run will have the same voltage which of course leads to longer bulb life and less burn-outs.

Conduit? I only use it when crossing beds where plants and flowers may need to be dug up and/or planted. Also,if lights may be a consideration down the road,I will use it under a new walkway.If doing a new install,I will just run the wire along the edge of a wall under the base......no problem.


Hope this helps.

[mrusk]

Adam on that bench seat install the back of the bench with some batter so it is more comfortable on the peoples back. Even with cushions no one will want to use a 90* bench.

[4seasons]

Adam
also when your doing your runs keep from having to use 14v or higher.
I dont even like to use 13v. Reason.... any light that the voltage is over 11.8 it wont get its true life out of the bulb.
So when your using 14v tap to get an 11.8 reading and 1 goes out the others are now running over that prime #. So it creates a chain reaction and they burn out faster.
Also don't touch the bulbs with your bare fingers.

[NCSULandscaper]

thats why the target voltage I use is 10.8V, you have some room to play with, and to be honest, ive not seen a noticable difference in brightness from 10,8 to 11.8

[JZap]

I think ZX hit the nail on the head. I would use a 600 watt and run a split lead of equal lights for 2- 300w leads. I used 1.25" electrical (grey) conduit under all patio and daylight on the outside of the wall with an access box which we usually hide with landscape.

[Evening Star Lighting]

thats why the target voltage I use is 10.8V, you have some room to play with, and to be honest, ive not seen a noticable difference in brightness from 10,8 to 11.8

As per the NEC (National Electric Code), you should use no more than 80% when calculating total lamp load.

Here's an example:

Amps x Distance x 2 x Resistance/Foot Amps = Watts / Volts.

The resistance per Linear Foot of wire needs to be calculated IN ADDITION to your fixture's wattage.

If your using-

12/2, the resistance per foot is .00162 The maximum Amps is 20 (240 Watts)
10/2, the resistance per foot is .00108 The maximum Amps is 30 (360 Watts)
8/2, the resistance per foot is .00064 The maximum Amps is 40 (480 Watts)

Integral uses 10 Watt Halogen lamps, so 10 Watts x 15 fixtures = 150 Fixture Watts / 12 Volts = 12.5 Amps. You have a 45' run (which doesn't sound right for that many lights), so using the voltage drop formula above for 12/2, we can calculate 12.5 Amps x 45 Linear Feet x 2 x .00162 = 1.82 Voltage Drop. Add that to 12, and you will need to use the 14 volt tap. (13.8 actual)

Keep in mind, Halogen lamps need to operate not less than 11.5 volts! Halogen lamps cycle- the Tungsten Halogen filament atoms burn off and mix with the halogen gas. The correct voltage will allow this gas mixture to re-deposit back to the filament, and not the glass. Incorrect calculations and/or voltage taps will greatly reduce lamp life, which can be seen by blackened bulbs.

ESL

[NCSULandscaper]

all i can say is 8 years later on all of the halogen bulbs ive put in at 10.8V are still burning clear

[MuirView Design]

Adam on that bench seat install the back of the bench with some batter so it is more comfortable on the peoples back. Even with cushions no one will want to use a 90* bench.

In hindsight Matt, you're absolutely right. Unfortunately, We already built the bench at 90 degrees with the back and it is a little uncomfortable. If we ever build one again, I will keep this in mind.


As far as the lighting, thanks for all the advice. I'm still a little uncertain about how to work the hub system. Anyone have any good instructional resource sites? The homeowner added two more lights today and decided to change three of the integrals to the 18". So that makes 16 - 6" integrals and 3 - 18", with 2 uplight add ons in the spring. I definitely think that the 300W transformer will be pushing it now, so we will probably go up to a bigger one. Using Evening Star's formula, I calculated my voltage drop to be over 2.6. Would I be okay using the 14V tap considering?

[JZap]

Well, besides the obvious classes offered from manufacturers'. I actually refer to a few past catalogs which usually have some good insight on guidelines for lighting systems. The Focus catalog has a few pages on setting up bigger systems. One thing I think might be helpful in these jobs is a direct burial transformer to completely hide the ugliest part of the system.

[Evening Star Lighting]

It sounds complicated, but it really isn't. You add the voltage drop to 12 volts (fixture's operating voltage) and round up to the nearest tap. IF someone adds fixtures, OR upgrades bulbs to a different wattage, that can overload the system, or cause premature bulb failure.