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Wire size for tankless water heater |
50-60 amp breaker use 6 gauge / Buy: 6-2 wire Southwire electric tools NMB is house wiring UF is underground |
40-50 amp breaker use 8 gauge / Buy: 8-2 wirebr> Southwire electric tools NMB is house wiring UF is underground |
30 amp
breaker use 10 gauge / Buy: 10-2 gauge/ 30 amp 10-3/ 30 amp Southwire electric tools |
Buy circuit breakers Eaton CL series circuit breaker CH circuit breakers at Amazon Federal Pacific circuit breaker QO circuit breakers at Amazon |
Buy circuit breakers Choose from 15 to 125 amp Siemens circuit breaker GE circuit breakers at Amazon |
What amperage and how many
breakers are needed? -Breakers must match the same brand as main panel. Look at label located on side of tankless unit for volts and watts. Watts divided by volts = amps -Look at product manual or spec sheet for description of wiring: for example 3 x 50 means three 50 amp breakers. 2 x 40 means two 40 amp breakers. -Each breaker supplies power to one element. Each element will have a set of two terminals. Wire from one breaker cannot be split to supply more than 1 element. -Look at screw terminals located inside unit to determine how many wires are needed: 2 terminals= 1 wire, 4 teminals = 2 wires. 6 terminals = 3 wires |
Screws on main breaker are HOT at all times Even when main breaker is OFF, both screws are HOT Only if meter is PULLED are these screws safe to touch |
What size
breaker and wire for tankless? 240Volt ratings: greater than 7.7 Kw= 7600 watts / 40 amp breaker/ 8 gauge wire greater than 9.6 Kw = 9600 watts/ 50 amp breaker/ 6 gauge wire greater than 11.5 Kw = 11500 watts/ 60 amp breaker/ 6 gauge wire greater than 13.4 Kw = 13400 watts/ 70 amp breaker/ 4 gauge wire -This information applies to 208-240 volt single-phase voltage |
Example shows terminal connections for 3 wires from 3 breakers Single wire cannot be split apart to connect to multiple terminals. Typical tankless requires 40-50 amp breaker for each wire. Each wire supplies 1 element. This example requires 3 breakers rated 40-50 amp = 120+ total amps. If you have 150 amps main breaker: 150 amps x 80% = 120 amps safe maximum so there is no electricity left for other appliances. 250 amp main breaker : 250 x 80% = 200 amps, so there is less than 80 amps for other appliances. Electric elements cannot heat water as fast as natural gas or propane gas. Tankless electric water heaters consume large amount of electricity To reduce energy consumption, add a tempering tank to preheat incoming cold water, keep thermostat set low, reduce consumption, add low-flow shower heads. If water moves too slowly through the pipe, or water pressure is low, or incoming water is too cold for amount of heating required, tankless may not activate. |
Double
check wire size and distance
100'-150' etc requires larger diameter wire 240 volt/ each breaker greater than 7.7 Kw= 7600 watts / 40 amp breaker/ 8 gauge wire greater than 9.6 Kw = 9600 watts/ 50 amp breaker/ 8-6 gauge wire greater than 11.5 Kw = 11500 watts/ 60 amp breaker/ 6 gauge wire 13 Kw = 13400 watts/ 2 60 amp breakers/ 6 gauge wire Resource: Select correct wire and breaker size |
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to:Page 1: get started Next: Page 3: connect wires to main breaker panel Page 4: Connect tankless to subpanel |
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