Caution: To prevent severe shock or electrocution always turn the power OFF at the service panel before working with wiring.
Never Assume the power is off! Always double check, and test the device before you begin work.
It is important to note that electrical codes change, and that in some areas local electrical codes are not the same as the National Electrical code. The local authority having jurisdiction in your area may have different codes than the national code. It is important to find out if your local codes differ from the national code, your local authority having jurisdiction is the final judge and jury.
The National Electrical Code states that “A means shall be provided to disconnect each appliance from all ungrounded conductors”. What doses this mean for you when wiring your home?
If the appliance or device you are wiring is more than 50 ft away from the electrical panel, or not within sight of the electrical panel, you must have a means of disconnecting the power. If you cannot see your electrical panel or if you can see it but it is more than 50 ft away you will need a disconnect.
Acceptable Means of Disconnect
1) A plug is acceptable to use, this would cover appliances such as your stove, refrigerator, dryer etc. Do not direct wire these appliances, you need to have the plug as a means of disconnecting power.
2) A Thermostat with a clearly marked off position that directly opens all ungrounded conductors and cannot turn on when in the off position can be used as a means of disconnect for electric baseboard heating.
3) Your hot water heater, furnace, well pump or central air conditioning unit all require an electrical disconnect if you cannot see your electrical panel from the location or if you can see it but it is more than 50 ft away. The hot water heater and furnace may or may not need one, while the central air unit and the well pump will always need one.
The disconnect will need to be in sight of the appliance or motor, it will need to have the ability to fully disconnect the hot conductors from the unit. It also needs to be capable of being locked out.
Make sure you use the proper size disconnect!
How to wire a disconnect
Example: If the current draw is 28 amps, you will need a disconnect rated for 30 amps.
If the current draw is 48 amps, you will need a disconnect rated for 60 amps.
The Line side is the cable supplying voltage from your electrical panel.
The Load side is the side that is connected to what you are supplying power to.
The grounds connect to a lug that is screwed to the disconnect enclosure. If there is not already one pre-installed you will need to install one by screwing it to the enclosure. It doses not matter where it is placed.
If a neutral conductor is required you will need to install an isolated neutral bar and make the connection there, or purchase a disconnect that has an isolated neutral bar already installed.