Hi, I have had the smok TFV4 series tank that came with a single coil RBA (TF-R1) and I've made up countless coils trying to figure out how to lower the voltage. I am sorta new to RBA's and I want to be as safe as possible before I really start using them. I am currently using an IPV4 mod. At 40 Watts, using 28 AWG Kanthal A1 wire, using two wires wrapped around each other, making 4 wraps, I achieve 5.44v at 0.74 ohms. Is this considered 'safe' and can I have a link as verification of source, please? I have also been practicing with NI200 Nickel wire with other RDA's. Any advice on this would also be greatly appreciated.