Woodshop Electric Basics
Mains Voltage can kill you. If you’re unsure of what your doing, then call a competent licensed electrician.
Unless your brother-in-law is a licensed electrician, don’t let him near your stuff.
Always work with the power disconnected (at the main breaker).
Don’t assume it was done correctly
Existing wiring can be plagued with issues, even if it works !!
Competent licensed electricians are often responsible for 30-40 house builds at a time and use “helpers”, some of whom are un-licensed, incompetent, and may deliberately hide their mistakes.
Any electrical work by the prior homeowner is suspect.
All electrical work must be done by a licensed electrician, however…
Local codes generally allow an homeowner to do his own work, but ….
An electrical permit must still be pulled, regardless.
Code and Certifications
The National Electrical Codes sets the standards nationally. Local codes maybe more strict.
Always use UL listed devices. Fail to do so may result in denial of a claim for fire damage.
Don’t rely on the meaningless CE mark. Only good in a few European countries. Self certification of conformity; no independent testing. Jokingly referred to as “Chinese Export”.
The CSA mark is for Canada.
Wire gages and amperage
Wire gauge must match the anticipated load (measured in amps).
Wire gauge must match the rated circuit breaker.
In residential wiring 14 and 12 gauge wiring is the most common for lighting and outlets.
In the shop use 12 and 30 gauge wire for most stationary tools.
8 and 6 gauge is used for driers, ovens, etc.
Indoor Cable Types
Romex – Non-Metallic (NM) Cable
Must be out of reach or protected by drywall
Never put in EMT conduit
12/2 means – two 12 gauge current carrying conductors + a ground
THHN in EMT
Thermoplastic, high heat, Nylon coated (THHN)
Separate strands installed in Electrical Metallic Tubing (EMT) conduit
Observe Fill Chart
Metal Clad (MC) Cable. Also called BX, armored, and Greenfield
Wire is pre-installed
Use a Voltage Detector for
Non Contact Voltage (NCV) detector
Presence of voltage without coming into contact with bare wires
Use a Receptacle Tester for
Testing correct wiring of outlets
Use a Multimeter for testing:
Continuity (measured in ohms)
Use an Amperage Meter for testing:
Current (measured in amps)
Polarity & Color Code
DC – Direct Current (think battery) has a positive and negative terminal
Red is +, Black is –
AC – Alternating Current (think household wiring) has a hot and neutral wire
The hot wire is connected to a gold colored terminal (narrow blade)
The neutral wire is connected to a silver terminal (wide blade)
Black is “hot”, white is “neutral”, green is “ground”
Always ground metal boxes
Never cut off the ground pin on a plug
Neutral and ground wires are bonded at the load center – Never anywhere else
Only at first service disconnect point, AND the utility has only provided normally current carrying conductors (phase and neutral wires)
Never at a sub-panel
Never use the Neutral wire as Ground, never use the Ground wire as Neutral
The Neutral should NEVER conduct current. It is there for safety ONLY.
Ground should be connected to a 10’ copper clad rod driven into earth
Typical Panel Bus Bar Layout
Power supplied to house will be: Line (leg) 1 & 2, plus neutral
Circuit breakers must match the load center. In our demo we’ll be using Square-D “Homeline” products. Do not modify a breaker to fit !
Loaded correctly, half of all breakers will be on bus A, half on bus B
220v breakers will be on busses A and B
Double breakers can be installed in some or all positions. See instructions for load center
Never touch the bus bars !! They are always energized and can kill you !!
Demo: Convert Machine from 110v to 220V