Say 4volts ÷ say .8 ohm you get 5 amps
5amps at only 4 volts only gives you 20 power/wats. Not good,in my opinion, for Clapton. You need more power or less resistance,or both, by using nichrome or ss. Lower gage core and higher for the wrap. I like 24or26 with 36. Hope that helps.