I want to use a relay for aftermarket seat heaters. I purchased a 4 pin relay rated at 30 amps. Each seat heater is rated at 4.5 amps for a total of 9. I am planning to run a positive wire, 14 ga no longer than 6 feet, from the fuse box under the hood where I can get constant power. There are a couple of fuses under the dash where I can get power that is controlled by the ignition switch using the piggyback style jumper. If I use the keyed power to control the relay on/off and the wire from under the hood for the power to the seat heaters, will this be a safe and reliable way to do this job? 2015 Honda Fit