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Connect tankless to main breaker box
Use only 600 volt wire.
Lamp cord, extension cords are not rated 600 volt.
Use copper wire only. Aluminum wire is fire risk and should be avoided or installed by professional.

30 amp breaker use 10 gauge /


Buy:
10-2 gauge/ 30 amp
10-3/ 30 amp
Southwire electric tools
Yellow 12 gauge 20 amp


Yellow/ #12 gauge wire for 20 amp
with ground
Buy:
12-2 gauge/ 20 amp
12-3/ 20 amp

NMB is house wiring
UF is underground
Rolls of stranded wire
White 14 gauge 15 amp


White/ #14 gauge wire for 15 amp
with ground
Buy:
14-2 gauge/ 15 amp
14-3/ 15 amp

NMB is house wiring
UF is underground
armored cable
Buy:
Armored cable
Southwire armored cable cutter
Southwire armored cable cutter
Buy:
Rolls of stranded wire

Stranded wire
stranded wire
Buy:
Rolls of stranded wire
50-60 amp breaker use 6 gauge /
6-2 wire
Buy:
6-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
40-50 amp breaker use 8 gauge /
6-2 wire
Buy:
8-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
    
Copper ground wire
Use same size as other wire in circuit

Buy:
12 gauge copper ground wire
Ground wire
Green ground wire
Ground pigtails
Ground rods/ ground clamps at Amazon

Buy
End cutting nippers at Amazon


When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistances on wire and creates weak point.
Buy tools:
Wire strippers at Amazon
Linesman pliers
Utility knife at Amazon
multimeter
Buy:
Multimeter
Electrical testers
GE-Breakers

Buy circuit breakers
Eaton CL series circuit breaker
CH circuit breakers at Amazon
Federal Pacific circuit breaker
QO circuit breakers at Amazon
double-pole breaker
Buy circuit breakers
Choose from 15 to 125 amp
Siemens circuit breaker
GE circuit breakers at Amazon
How many breakers? What size breakers?
-Breakers must match the same brand as main panel.
-Applies to 240 volt single-phase tankless water heaters
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 terminals = 2 wires. 6 terminals = 3 wires
Main breaker warning
Screws on main breaker are HOT at all times
Even when main breaker is OFF, both screws on the main breaker are HOT
DO NOT touch main breaker screws at any time unless meter is pulled
To replace main breaker, power company must unlock metal band around meter and pull out the meter.

Resource:
What causes electrocution?
Electric safety
Main breaker box for tankless electric
Larger image
Three 50 amp 240Volt breakers
Use 50 amp breaker with 6 gauge wire
No difference if all breakers on same side of panel, or on different sides.
Requires 250 amp service and 250 amp main breaker.


Ground wire must be connected to ground busbar
Resource
Wire size chart
Main breaker Stress test

Buy:
Circuit breakers at Amazon
Shop Amazon - Industrial Electric Products
Back to:
Page 1: get started
Page 2: select wire and breaker size

Next:
Page 3: connect wires to main breaker panel
Page 4: Connect tankless to subpanel
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