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220 question
- Thread starter kand3g
- Start date
I've noticed that some 220 have 4 wires and others only have 3. In a 4 wire application, what is the white wire and where should it be connected in the panel?
Any appliance that has 120 volt controls, needs a neutral wire, so no current is flowing on the bare ground. Electric Range, dryer needs 4 wire circuits. Water Heater, Central AC do not, can be fed with three wires (2 hots and ground)
Crazyjake8493
Well-known member
The white wire (neutral) would go to the neutral bar in the panel, whereas the hot wires (black/red) would both go to the 2-pole breaker.
In a dual 120/240V appliance, such as an electric range, the 240 volt components (burners) would use the black and red hot wires, and bare ground. The 120 volt components, such as the clock and light, would use only one of the hot wires, the white wire as the neutral, and the bare ground.
In a dual 120/240V appliance, such as an electric range, the 240 volt components (burners) would use the black and red hot wires, and bare ground. The 120 volt components, such as the clock and light, would use only one of the hot wires, the white wire as the neutral, and the bare ground.
theoldwizard1
Well-known member
Kand3q, what you are seeing is old National Electric Code versus present NEC. Electric dyers and ranges used to be 3 wire. They are all now 4 wire. 2 hots, neutral and ground.
ForceFed70
Well-known member
3 wires = 240V circuits only (no neutral conductor). All aspects of appliance must run on 240V
4 wires = 240V and 120V circuits available. Appliance could run some loads at 120V if needed.
4 wires = 240V and 120V circuits available. Appliance could run some loads at 120V if needed.
matt_i
Well-known member
All aspects of appliance must run on 240V
Very common in machine tools is the use of a 50-100VA control transformer, 240vac primary, 120vac secondary for running relay coils and work lights. However, read that again from a pure economic standpoint: the manufacturer must supply the transformer at their cost. If they simply require a 4-wire hookup, the cost of the 120vac control is borne by the consumer.
lazer50
Well-known member
All the codes aside the white is the neutral and connects with the other white wires in tour panel.red and black to breaker bare is ground.
Speedy Petey
Well-known member
Not entirely true. As Theoldwiz stated, older dryers and ranges, and even some sub-panels, were allowed to be "3-wire" 120/240V circuits, where the neutral also served as the equipment ground.3 wires = 240V circuits only (no neutral conductor). All aspects of appliance must run on 240V
4 wires = 240V and 120V circuits available. Appliance could run some loads at 120V if needed.
Not entirely true. As Theoldwiz stated, older dryers and ranges, and even some sub-panels, were allowed to be "3-wire" 120/240V circuits, where the neutral also served as the equipment ground.
agreed. The 4th wire was added for safety. In a 3 wire application, if there happened to be a fault or loose connection in the ground wire, the frame of the appliance could become live.
With a 4th wire, you now isolate the power from the appliance frame and give yourself a backup ground.
agreed. The 4th wire was added for safety. In a 3 wire application, if there happened to be a fault or loose connection in the ground wire, the frame of the appliance could become live.
With a 4th wire, you now isolate the power from the appliance frame and give yourself a backup ground.
The third conductor is a neutral for cooking equipment and dryers it was allowed to ground the frame of the appliance to the neutral, and still allowed in existing locations.