As stated in previous posts this week, the voltage is not 12V, it is actually higher. Just thought I would make that correction... 400W/13V=30.7A #10ga is actually good for 35A. Remember that these conductors are in "free air" and have nothing to really trap the heat. But, I have the 2 relay set up on mine as it is much easier to deal with #12 wire.
Doug -----Original Message----- From: John Caldwell [mailto:[email protected]] Sent: Thursday, August 30, 2001 4:26 PM To: [email protected] Cc: [email protected] Subject: Re: Current Flow: Attn Electrical Engineers On Thu, 30 Aug 2001, Mark Reda wrote: > Hey guys, I was hoping that some of the Electrical Engineers (certified or > not) on the list could help me out. > I want to determine what wiring, relays and fuses are necessary for 100/80W > bulbs. > What formula's apply to this application? > amps = watts / volts Take the total number of watts that will be on one circuit, divide it by 12v, and you'll get the total amperage draw that you'll be getting. I coulda sworn that I already went into this, but... Assuming 100W 7" rounds, and 100w inners, that's 400W total. 400W / 12 = 33A. To give yourself a little buffer room, you'd want 35 or 40A of capacity, in fuses, wire, and relays. You're gonna have a tough time finding relays that big at a regular auto parts store, so you can just use two 20A relays and use one for each side. Since the low beams are only going to be 160W or 13A total, you can use one 20A relay for them. Use the same rule for relays and fuses, they're rated the same way. You might want to stick with a fuse that's slightly smaller than the maximum rated load for the relay, so the fuse will blow before the relay. Here's an excellent page that will answer a lot of your questions, especially about wire size: http://www.rallylights.com/other/wiring.htm Using the chart they have, you should be using at least 14ga wire. I would stick to 10 or 12, since there will be even less of a current drop across the larger wires. It would be pretty impossible to terminate 8ga. wire into a h4 connector... 12 was hard enough! _____________ List Sponsor: http://www.netsville.com To remove yourself from this list, send mail to [email protected] with 'unsubscribe a2_16v' in the body of your message See us on the web at http://www.a2-16v.com Visit the 16V Homepage at http://www.gti16v.org _____________ List Sponsor: http://www.netsville.com To remove yourself from this list, send mail to [email protected] with 'unsubscribe a2_16v' in the body of your message See us on the web at http://www.a2-16v.com Visit the 16V Homepage at http://www.gti16v.org
