Can anyone tell me what gauge wire I need to hook up my 5000 watt overhead heater ? I have 2 open 220 volt outlets and want to use one of these as a junction box to hardwire the heater. They each have their own breaker. The heater says it is 20.5 amps so the 30 amp breakers are okay but the installation instructions don't specify wire size. I guess they assume an electrician will install. Thanks