Residential Wiring

By: Ing. Hector M Lugo-Cordero, MS

03/25/2009

Agenda

• Residential circuits• Improving power consumption• Sockets• Switches• Cables• Protection devices• Service panel• Distribution panels• Electrical symbols

Residential Circuits

• Residential loads are connected in parallel, since the voltage remains the same through the loads and if a circuit fails it does not affect the others

• Purelly resistor load (e.g. lights, toaster)– Demand P = VIcos(av – ai)– cos(av – ai) is the power factor

• If a motor is added (e.g. celing fan, refrigerator) – Demand Q = VIsin(av – ai), as well as P– sin(av – ai) is the reactive factor

Improving Power Consumption

• Add a capacitor/capacitor block in parallel to the load

• Make sure is the right one

• Don’t add it to purely resistor circuits

Sockets

• A power socket is used for connecting appliances.

• Big hole specifies the neutral end (to source)• Small specifies the hot end (from source)• Examples

– 125V @ 15A– 125V @ 20A– 230V @ 30A– Ground Fault– Arc Fault

Switches

• Switches allow the user to control a load (on/off)

• Examples– Single– Double– 3 way– 4 way– Combined– Pilot light

Cables

• Black – hot, connection from the AC source to switch typically

• Red – return, connection from switch to load

• White – neutral, connection from load back to the AC source, it closes the circuit

• Green – ground, protects people from electrically charged metal parts

Size of Cables

• 14: minimum approved width in United States for residential wiring. In PR we can use it for lamps wiring

• 12: minimum approved width in Puerto Rico for residential wiring

• 2: cable used from service panel to distribution panel, passes up to 100A of current

Size of Cables (cont.)

Protection Devices

• Breakers: work like a fuse, opens current path when threshold is exceeded. This protects the circuits from high currents, no protection to people

• Ground connection: connection to ground so that users are protected from alternate current paths, like breakers they open the current path but when a current change is found

Service Panel

• Nude cable comes from transformer

• It then changes to a white cable and connects to the box

• From here a connection to breaker and ground is done

Distribution Panels

• Load balancing: the act of distributing equally all 120V loads

Electrical Symbols