bobair8(at)msn.com
Guest
|
 Posted: Sat Jan 13, 2007 5:45 pm Post subject: Voltage Regulator Wire Sizes: Do I Really Need 12 AWG? |
 |
|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Folks,
Per page 4-7 of the "Connection", I'm planning on running the Field and two ground wires from the B&C LR3C-14 to the battery in the back of my GlaStar. The round trip distance between the battery location and the regulator is (generously) about 40' (it may turn out closer to 35' depending on wire routing and final battery location).
Using the 5 Amp rating of the field breaker, my figuring using Figure 11-2 in AC 43.13 says to use a 12 AWG wire. That seems awfully "fat", especially since the B&C instructions specify 18 AWG. Fig. 11-2 indicates that 18 AWG will carry 5 Amps continuously for about 16', which sounds about right for the distance from the alternator to the regulator and from the regulator to a power buss on the panel.
Do I really need 12 AWG here? I don't recall seeing any information on the normal load on the Field wire. Since the B&C instructions call for redundant ground wires, can I use two 15 AWG for the ground wires and a 12 AWG for the Field wire?
(My calculations don't take into account that these voltage regulator wires would be bundled with the (2) 2 AWG "mains"; the two wires for the battery contactor and an "always hot" wire.)
Unrelated "bonus" question. I there any reason I can't bundle the Field wire from the alternator back through the firewall with the thermocouple wires for the CHT and EGT? This bundle will also have another wire from the alternator to a test point on the panel so I can measure the Field voltage from the cockpit per Bob's suggestion.)
Best regards,
Bob F.
[quote][b]
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
