I am wiring the LCD Hall Cullen Current Voltage Power Electric Energy Meter, 2001712003 into my RV to monitor the on-board battery. The provided 6″ and 19″ Hall Signal Cables are too short and I need to purchase or fabricate a longer cable (approximately 8′). I am having trouble locating the 24/3 signal cable. Can I effectively substitute 18/3 shielded cable, and could I splice this by using the provided terminal pins or purchase other terminals from you? If so, what would be the limit for the signal cable length?