This
advice is on how to correctly install an ELECTRIC DRYER or ELECTRIC RANGE
220-240VAC power cord (US Standards).
3-Prong or 4-Prong – The
Difference:
3-prong
color code:
BLACK (HOT – 110-120VAC) – May
also be referred to as L1
RED (HOT – 110-120VAC) – May
also be referred to as L2
WHITE (NEUTRAL – 0VAC) – Usually
grounded to the equipment frame via a jumper wire or metal strap.
4-prong
color code:
BLACK (HOT – 110-120VAC) – May
also be referred to as L1
RED (HOT – 110-120VAC) – May
also be referred to as L2
WHITE (NEUTRAL – 0VAC) – DO
NOT ground to equipment frame.
GREEN (GROUND) – Attach to
equipment frame.
Which One to Use: According to the National Electrical Code
(NEC), Article 250, installations after the year 2000, require the use of a
4-prong plug which incorporates a separate ground and neutral wire. If you currently have a home that uses the
3-prong receptacle and cord, you can continue to use it. You will have to upgrade to a 4-prong
configuration, however, if you plan on relocating your current receptacle, or
if the internal wires of the receptacle become damaged in any way and require
repair.
Converting
from 3-prong to 4-prong: Make sure you UNPLUG
the appliance prior to any repairs. CAUTION: Voltages dangerous to
life are still present even with the appliance turned off and still plugged
in. Notably in the area of the terminal
block where the power cords are installed.
You will need to remove the old cord by following these steps:
- With the appliance
UNPLUGGED, remove the access panel on the back of the unit where the power
cord enters.
- With the cover
removed, you will see a terminal block where the power cord is
attached. The terminal wires will
be colored with the WHITE wire in the middle, and the BLACK and RED wires
on either end. NOTE: There should be a green jumper wire or metal
bonding strap attached to the NEUTRAL (white) terminal wire.
- Remove the terminal
lugs holding the old power cord wires in place. CAUTION:
Use care not to drop any nuts or screws inside the appliance.
- Remove the bonding
strap or ground wire from the Neutral terminal lug. NOTE:
If disconnecting a ground wire, make sure you re-attach it to the
appliance frame.
- Loosen the screws on
the strain relief connector that holds the power cord in place and remove
old power cord. NOTE: If your appliance
does not have a strain relief that clamps down and hold the power cord in
place, it is highly recommended that you install one. This prevents chaffing of the power cord
against the appliance casing, and prevents the terminal wires from being
pulled and broken loose. This could
pose a potential shock hazard or cause damage to the appliance.
- Install new power cord
by threading it through the strain relief connector and tighten down the
screws.
- Connect the new power cord
to the corresponding colors at the terminal block (Black goes to Black,
Red goes to Red, White goes to White).
The difference is going to be a Green (ground) wire that will
connect to the appliance frame.
There’s usually a green grounding screw for this. NOTE:
If you disconnected a green grounding strap in Step 4., you can connect
these two wires at the same point.
- Re-install access
cover. Turn off the service breaker
to the appliance PRIOR to plugging it back in. With the breaker in the off position,
plug the appliance in, and THEN turn the breaker on. In the event, something was wired
incorrectly, it is far better to have your hands away from the receptacle
and controlled from a distance.
Safety first.
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