First of all, these two devices are one-way? If you are one-way and you and a loop-powered, are you looking for a 40A circuit breaker with leakage protection. This calculation, a total of 5.85 kilowatts two devices. Conservative about equal to 6 kW. Electricity voltage single phase 0.22 kV consider 0.8 (power factor why 0.8 is a professional, you know that the data just fine). Usually two devices operating at full capacity, the loop current is calculated as 6/0.22/0.8 approximately equal to 34A. Taking into account the family, the distance of the wire is not long, and Concealed in the wall, one-way 6 square copper wire ampacity just in case ambient temperature of 30 degrees is 34A. 6 square wire though you can use, but still not very reasonable. 'll Tell you why. Small inner tube circuit switch 34A profile, but also to meet 34A of equipment use, and amplification of adjacent 40A small switch should choose a file. This time the problem came out, although the front to help you calculate the carrying capacity of conductors are relatively conservative. But it is difficult to take into account the quality of domestic wire, so can not say if the phase current last more than 34A wire can the chin could not carry the consequences wire premature aging. And did you notice the loop with a small switch is 40A a file, that is the load 34A 40A following the switch does not trip! So in theory, with 6 square wire a little less reasonable. . Best with 10 square. The leakage switch to bring. Family of all electrical equipment, as long as usual to hand can touch the exposed metal should install the GFCI. Ground wire this should be needless to say you know. Upstairs says the device comes with leakage protection switch so without belt.