outdoor lights

[solo618]

Hey guys! I want to put lamp posts around my yard,7 actually with each post able to hold 3 lamps at 100 watts max, so i guess 300 watts per posts. okay so i figuered i'd put three posts on one 15amp ckt and 4 on another because i figured 80% of the 15 amp ckt is 1440 watts. The problem is the last post will be about 360ft from the panel. I'm worried about the voltage drop. At first thought i was thinking i should run #8 or would #10 be sufficient.

 

[480sparky]

7 posts * 3 lamps per * 100 watts per lamp = 2100 watts. 2100/120 = 17.5amps

You've already exceeded a 15-amp circuit.

 

[solo618]

sparky

sparky

i think you missed something in my post. i'm gonna put three posts on one 15amp ckt and 4 posts on another 15 amp ckt,so thtas two ckts.

 

[mdshunk]

If these are incandescent lamps, the voltage drop may work to your benefit by increasing the lamp life.

 

[LarryFine]

You might also consider using CFL's, which would bring your total load current to below 5 amps. #12 wire would be more than plenty.

 

[quogueelectric]

I would just run 10 wire to the hr point of the farther ckt you should be ok on 2 ckts. The lower amperage would have less VD. Make the 3 light circuit the farther one.

 

[solo618]

outdoor lights

Thanks for the responses so far.One other thing i just thought of. Do these ckts need to be fed from GFI breakers? I don't think it does but just wanna make sure.

 

[JohnJ0906]

Depends on how deep you want to bury the wire/conduit.
See Table300.5 and section 300.5.

 

[LarryFine]

Thanks for the responses so far.One other thing i just thought of. Do these ckts need to be fed from GFI breakers? I don't think it does but just wanna make sure.

Not if you bury the wire 18" or more. I'd dig the extra 6" over suffering the GFCI headaches any day.

 

[sparky59]

the last time i had a long run for yard lights i ran a mwbc with a 2 pole 20 amp breaker. use #12 thwn and alternate the circuits....1st light black wire...2nd light red wire ...etc. You only need one neutral and there's very little voltage drop.

 

[ItsHot]

going green

going green

You might also consider using CFL's, which would bring your total load current to below 5 amps. #12 wire would be more than plenty.

Larry you going green on us?:grin:

 

[RUWired]

With 14 awg cu., 360', 300 watts, your voltage drop will be over the recommended 3%. 12 awg will bring it up to less than 3%.10 awg will take it to 1.8%.

 

[mivey]

With 14 awg cu., 360', 300 watts, your voltage drop will be over the recommended 3%. 12 awg will bring it up to less than 3%.10 awg will take it to 1.8%.

check that math again.
I get (with #10 solid):
Section, amps, Sect ft, Tot ft, Source V, Load V, Sect %VD, Tot %VD
1, 7.5, 51.4, 51.4, 120.0, 119.1, 0.77%, 0.77%
2, 7.5, 51.4, 102.9, 119.1, 118.1, 0.78%, 1.54%
3, 7.5, 51.4, 154.3, 118.1, 117.2, 0.78%, 2.31%
4, 7.5, 51.4, 205.7, 117.2, 116.3, 0.79%, 3.09%
5, 7.5, 51.4, 257.1, 116.3, 115.4, 0.8%, 3.86%
6, 5, 51.4, 308.6, 115.4, 114.8, 0.53%, 4.37%
7, 2.5, 51.4, 360.0, 114.8, 114.4, 0.27%, 4.63%

 

[George Stolz]

You might also consider using CFL's, which would bring your total load current to below 5 amps. #12 wire would be more than plenty.

Outside? Won't the cold be an issue in the winter?

 

[ultramegabob]

Outside? Won't the cold be an issue in the winter?

I havent had any problems with them due to cold temps, I use them in walk in cooler/freezer vapor fixtures also.

 

[George Stolz]

Good to know. Thanks!

 

[mivey]

I have had some problems getting CFL floods to light in the winter.

 

[ultramegabob]

I have had some problems getting CFL floods to light in the winter.

Phillips makes ones specifically for outside fixtures.

 

[jdsmith]

A lot of the GE CFL's are rated to start down to 5 degrees F or 10 degrees F. The light output will be greatly reduced since rated output is at 77 F (or maybe some other temp in the 70's). Most people I've run across don't really care about the reduced output since they get warm fuzzies about CFLs.

 

[roger3829]

You might also consider using CFL's, which would bring your total load current to below 5 amps. #12 wire would be more than plenty.

If you use CFL's, you can't put them on a dimmer.