A10GAC
New member
I've been reading a few threads in the Accessory forum and have notice a fair amount of electrical questions. Hopefully I can help with some of the confusion.
Abbreviations:
Current (I), Voltage (V), Resistance (R), Wattage (P)
How to solve for current (Amperage)
I = V/R or I = P/V (ie a single 55w light at 12v draws 4.58Amps)
Solving for Wattage
P = I * V or P = I(Squared) * R (ie 5Amps at 12v = 60Watts)
Relays are used to isolate switches from high current draws, this is not only going to give you a longer switch life but if you are using a metal bodied switch it could save you from an uncomfortable shock if the switch shorts internally. Most driving/fog light combos will draw anywhere from 9 Amps for a 55w set to 15Amps for an 80w set. Keep in mind that these numbers are for a static load, the initial current surge can be 25 to 40% higher when you first switch the item on.
Any connections such as splices, ring terminals, solder joints will increase the overall resistance in the circuit and draw down the voltage lowering the performance of the accessory. Since they are also points of failure it's always best to keep the number of connections to a minimum.
The chart below is from RallyLights.com and is pretty useful for most shop projects. These guys have an excellent handle on wiring safely.
**Edit: Ok the formatting of the chart was a royal pain, the link above will take you directly to the Rally Light page & chart.**
Calculate the current load and find the next highest on the top row. Go down that column until you find the length you need to run. The wire gauge required is shown in the far left column. The maximum lengths are based on a 1/2 volt drop over the indicated length. To be safe, always choose one wire size larger than you need for the required current carrying capacity and length. For example: You
Abbreviations:
Current (I), Voltage (V), Resistance (R), Wattage (P)
How to solve for current (Amperage)
I = V/R or I = P/V (ie a single 55w light at 12v draws 4.58Amps)
Solving for Wattage
P = I * V or P = I(Squared) * R (ie 5Amps at 12v = 60Watts)
Relays are used to isolate switches from high current draws, this is not only going to give you a longer switch life but if you are using a metal bodied switch it could save you from an uncomfortable shock if the switch shorts internally. Most driving/fog light combos will draw anywhere from 9 Amps for a 55w set to 15Amps for an 80w set. Keep in mind that these numbers are for a static load, the initial current surge can be 25 to 40% higher when you first switch the item on.
Any connections such as splices, ring terminals, solder joints will increase the overall resistance in the circuit and draw down the voltage lowering the performance of the accessory. Since they are also points of failure it's always best to keep the number of connections to a minimum.
The chart below is from RallyLights.com and is pretty useful for most shop projects. These guys have an excellent handle on wiring safely.
**Edit: Ok the formatting of the chart was a royal pain, the link above will take you directly to the Rally Light page & chart.**
Calculate the current load and find the next highest on the top row. Go down that column until you find the length you need to run. The wire gauge required is shown in the far left column. The maximum lengths are based on a 1/2 volt drop over the indicated length. To be safe, always choose one wire size larger than you need for the required current carrying capacity and length. For example: You
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