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Discussion Topic:
Circuit Breaker
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Joe2009 |
11-30-2009 @ 2:39 PM
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Member
Posts: 13
Joined: Oct 2009
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I must replace circuit breaker for the lights, which is mounted on the inside firewall via a circuit board, on my '39 Ford coupe. What is the current rating that should be used. Note that I have converted to 12 volts.
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trjford8 |
11-30-2009 @ 6:28 PM
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Senior
Posts: 4215
Joined: Oct 2009
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30 amps should do it.
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supereal |
12-01-2009 @ 10:12 AM
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Senior
Posts: 6819
Joined: Oct 2009
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Assuming that your headlights are the standard 55 watt variety, at 12 volts the current draw will be just over 10 amps. Current is determined by dividing wattage by voltage. Thus, 110 watts at 12 volts equals 9.17 amps. Lights are resistive devices, so load calculation for motors and other devices must take into consideration starting load and other reactive factors. In old cars, poor connections and undersized conductors can skew the load needs, particularly on 6 volts. Headlights at 6 volts increase the load to just under 20 amps. As Tom suggests, 30 amps should be more than adequate.
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