Outdoor Low Voltage Lighting - Electrical - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical


Thread Tools Display Modes
Old 07-07-2008, 09:31 PM   #1
Join Date: Feb 2008
Location: White Plains, New York
Posts: 13
Rewards Points: 10

outdoor low voltage lighting


I have recently replaced walkway lights. I had to upgrade my transformer to a 300w, although I am only drawing about 120w. My old transformer died and the old lights only used about 60w total.
I have no idea what size cable I am using- it was the existing and everthing seems ok, but I don't want a fire. My guess is it is 16 or 18 guage. It is a 50 ft run.
I know for 300w transformer they recommend a 12 guage wire but as I said, I am only using 120w. Does this matter, or do I need to run new cable?
I would rather not dig it up if I didn't need to.


DDASH is offline   Reply With Quote
Old 07-08-2008, 06:30 AM   #2
Electrical Contractor
jbfan's Avatar
Join Date: Jun 2004
Location: Newnan GA
Posts: 6,979
Rewards Points: 554

My guess is that you have #14 wire now. I have never seen #16, or 18 for lowvoltage outside wire.
If it is infact #14, then I would not change it, unless you add more lights.


"The problem isn't that Hillary Clinton lies. We all know she lies. The problem is that her supporters don't seem to care"
jbfan is offline   Reply With Quote
Old 07-08-2008, 08:56 PM   #3
Idiot Emeritus
Join Date: Mar 2008
Location: Fernley, Nevada (near Reno)
Posts: 1,849
Rewards Points: 1,492

If the load is 120 watts, and the voltage is 12, the current will be 10 amps.

The resistance of #14 wire is about 2.6 ohms per thousand feet. Your 50' run is actually 100' (50' out, and 50' back). You'll lose about 2 volts or so. (The reason it's not 2.6 is because the 12 volt lamps are operating at less than 12 volts, so the current will be less.) There's nothing wrong with this, the #14 wire can handle the load, and operating 12 volt lamps at 10 volts will make them a bit dimmer, but will make them last much longer.

If it were #16 wire, you'd be losing about 4 volts. The lamps would be noticeably dimmer, and if they're incandescent they'd be more of a reddish color than white. The #16 wire could still handle the current, but it'd be pushing it a bit.

If it were #18, you'd be losing about 6 volts. The lamps would be barely glowing, and would be reddish-yellow. You'd notice it for sure. The wire would become quite warm in just a few minutes.

If it all looks normal, I'd bet you have #14 wire. If there's a fuse in the transformer, make it 15 amp. That way, the fuse will blow way before the wire can overheat.

micromind is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Low voltage wire entering/exiting walls need box? Azeiku Electrical 2 07-07-2008 04:55 PM
low voltage lighting question please.. melissadurante Electrical 1 03-02-2008 12:55 AM
Low Voltage Cabinet Lighting Recommendations BigJimmy Electrical 2 01-20-2008 01:01 PM
Low Voltage Lighting Bulb Life IdahoBob Electrical 2 12-23-2007 12:24 AM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1