Office and Home Electrical Wiring and Safety
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Transcript of Office and Home Electrical Wiring and Safety
Office and Home Electrical Wiring and Safety
Session 10
U.S. Consumer Product Safety Commission Has Found:
Electrical Fires – Majority Caused by Aging Wiring and Misuse of Surge Protectors
In the U.S. Over 750 People Are Killed Every Year by Electrical Fires
Extension Cords - Leading Cause of Home Electrical Fires in the U.S. – An Extension Cord Related Fire Occurs Every 6
Minutes
General Electrical Safety
Replace Damaged Electrical Cords Do Not Run Electrical Cords Through
Doorways and Under Carpets Avoid Overloading Electrical Outlets If Switches/Outlets Feel Warm – Contact
service ASAP
General Electrical Safety
Appliances, Extension Cords, Power Strips,– Certified By an Independent Testing Laboratory,
Use Ground-Fault Circuit Interrupter (GFCI) Plugs Around Water– Test the GFCI Plug Every Month
Power/Extension Cord Safety
Never Remove the Ground Pin (3rd Prong) to Fit into a Two-Prong Outlet
Extension Cords: Use On a Temporary Basis – Not Intended for Use as Permanent Wiring – Heavy Use of Extension Cords Means There are Too
Few Outlets to Meet Your Needs
Power Strips
Only Allow the User to Plug in More Products into the Same Outlet -
Avoid Exceeding the Capacity of the Electrical Outlet
Never Overload the Capacity of the Power Strip
Only Plug One Power Strip into a Single Duplex Electrical Outlet
Never Plug Power Strip into Another Power Strip
Electrical Wiring – Basic Concepts
NEVER work on a live circuit
it can be dangerous. In every junction box
there is generally only
one hot wire bringing
power into the box. Separate all the wires
first so none touch each other.
Installing home-electrical-wiring for breakers and fuses inside a breaker box
Use Right Size of Electrical Wire!
Wire Size Wire Rating (Amps)
Breaker Rating (Amps) Common Use
#14 15 Amps 15 Amps Lighting Circuits
#12 20 Amps 20 Amps Outlet CircuitsDedicated Microwave Circuits
#10 30 Amps 30 Amps Heavier duty electrical appliance (oven, dryer, etc)
#8 40 Amps 40 AmpsSub-panel feed lineSpecialty equipment with a big motor
#6 55 Amps 50 Amps Main service feed – older home
#1 105 Amps 100 Amps Main service feed – newer home
How to Determine the Capacity of a Power Cord or Power Strip
Assume 125 Watts per Amp to Calculate the Conversion
Total Watts Should Not Exceed 80% (0.80) of the Rated Capacity
Example – Surge Protector Rated at 15 Amps15 Amps X 125 Watts/Amp = 1875 Watts
1875 Watts X 0.80 = 1500 Watts Capacity of the
Surge Protector
Example of Multiple Items Plugged into a Surge Protector
Multiple Items Plugged into a 15 Amp Surge Protector: – Computer – 2 amps = 250 Watts– Monitor – 1.2 amps = 150 Watts– Coffee Maker – 650 Watts– Laser Printer
Idle – 2 amps = 250 WattsPrinting – 9.4 amps = 1175 watts
Example of Items Plugged into a 15 Amp Surge Protector (Continued)
Total Wattage While Printer is Idle:250 (Computer) + 150 (Monitor) + 650 (Coffee Maker)
+ 250 (Printer in Idle) = 1300 Watts Total Wattage While Printer is Printing:
250 (Computer) + 150 (Monitor) + 650 (Coffee Maker) + 1175 (Printer Printing) = 2225 Watts
While Printing, the 1500 Watt Surge Protector Capacity is Exceeded! – Plug the Printer into a Separate Surge Protector & a Different Duplex Plug
Mapping Electrical Circuits in Your Home
Record the amperage rating for each circuit (identified on the breaker or fuse) as well.
Record the gage (diameter or thickness) of the wiring in each circuit, typically marked on the plastic outer jacket containing the wires. If it’s 14 AWG, the circuit should be protected by a breaker or fuse no larger than 15 amps. If it’s 12 AWG — 20 amps at most. If it’s 10 AWG (such as most clothes-dryer circuits) — 30 amps maximum.
It is critical the circuit breaker that protects a circuit be of the right amps rating for the size of the wire.
Most circuits in your home are 15 amp and 20 amp, but no matter what, it is again CRITICAL that breaker rating be appropriate for the wire rating.
If the breaker rating is too low, the breaker will trip before the wire capacity is close to being reached.
If the breaker rating is too high, the wire can get too hot and potentially start a fire.
inspecting the electrical panel:
1. Incoming wire size10. Breaker types that don’t match panel type
2. Panel amperage rating (size) 11. Rusting/Corroding 3. Size of Main Breaker4. Wire size/breaker size not proper 13. Over-fused wires5. Type of wires—aluminum or copper 14. Breakers turned off6. Loose connections 15. Breakers “tripped” off7. Re-identified conductors8. Damaged wires9. Water intrusion