ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Happy Thanksgiving all!
by gfretwell - 11/30/22 05:55 PM
EMC Glands on Motors
by gfretwell - 11/30/22 05:53 PM
Ground Rods: Installation and Hook-Up
by gfretwell - 11/30/22 05:45 PM
Colt Firearms Switchbox
by NORCAL - 11/29/22 01:04 AM
Perfect work light?
by gfretwell - 11/22/22 12:48 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
1 members (Scott35), 65 guests, and 12 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#170854 11/13/07 08:15 PM
Joined: Sep 2003
Posts: 114
B
Member
I'm running some long 12 Volt circuits to rope lighting and I'm needing to figure out the voltage drop. I have already put in 12-2 12 volt landscape wire. I need to find out what the resistance for this wire is. It seems to have more strands than stranded #12 so I don't think that Ohm value is what I want.

Any help?


Joined: Jul 2002
Posts: 8,430
Likes: 3
Member
Do you have any loss figures for the wire itself?
In that, usually there are stated losses for a given size of wire given as mV per Amp per metre (foot?) this is then used to calculate the total voltage drop of the circuit.
BTW, if you are trying to find the resistance of that wire, you'll be needing a low-ohm meter or a really accurate multi-meter.

Joined: Sep 2003
Posts: 114
B
Member
I have no intention of using a meter to calculate it myself. I know there are tables for cross-sectional are of conductors but like I said this wire is stranded with probably twice as many strands as #12 THHN stranded.

Joined: Sep 2003
Posts: 114
B
Member
I guess the question I'm really needing answered is does the voltage drop formula differentiate between stranded and solid wire.

Joined: Sep 2003
Posts: 114
B
Member
http://www.generalcable.com/NR/rdon...E3F73914A/0/Pg37_LwVltgLndscpLghtgWr.pdf

That is about as close to specs as I can get. It is one of the #12 wires toward the bottom. I still don't think any of that information will help.

Joined: Sep 2003
Posts: 114
B
Member
Something isn't right. Can someone advise me on this.
Ed = (12*I*L*2)/CMA

Ed is allowable voltage drop
I is amps
L is length in feet
and CMA is Circular Mils

In this case:
I = 13.3 (8 20 watt bulbs 12Volt)
L = 40'
CMA is 6530 for #12

This means that Ed is about 16%(1.955 volts).

I know from experience we have put many out door lights on a transformer and have had no problems (watts ? can't remember). What gives?



Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *
2023 National Electrical Code (NEC)
2023 NEC Now Available!
 
* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Niko
Niko
Campbell, CA
Posts: 356
Joined: August 2006
Top Posters(30 Days)
Trumpy 7
NORCAL 5
Popular Topics(Views)
300,341 Are you busy
230,001 Re: Forum
214,810 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5