1.8   Electrical Safety

Electrical fires and shocks are common and serious safety prob­lems. Electrical safety is a basic housing need, requiring atten­tion during weatherization and repair.

Observe the following specifications for electrical safety in weatherizing existing buildings.

✓     When any weatherization, health, or safety procedure requires working with line-voltage power, a licensed elec­trician must do the procedure.

✓     Whenever working around wiring, use a non-contact volt­age tester to determine whether circuits are live. Turn cir­cuits off at circuit breakers as appropriate.

✓     Inspect wiring, fuses, and circuit breakers to verify that wiring isn’t overloaded. Maximum ampacity for 14-gauge wire is 15 amps and for 12-gauge wire is 20 amps.

✓     Confirm that all wire splices are enclosed in electrical junction boxes. If you plan to cover a junction box with insulation, attach a flag to mark its location.

✓     Don’t allow metal insulation shields to contact wiring.

✓     Verify that the electrical system is grounded to either a ground rod or to a metallic water pipe with an uninter­rupted electrical connection to the ground.

✓     If installing insulation, install S-type fuses where appropri­ate to prevent occupants from installing oversized fuses.

✓     If installing insulation, perform a voltage-drop test to eval­uate the size and condition of hidden wiring on older homes. Use a “Sure Test Branch Circuit Analyzer”, or simi­lar device that measures the voltage drop at full load (15 amps). Voltage drop may not exceed 5%.

✓     When you doubt the safety of a building’s electrical sys­tem, use a generator to power insulation blowers and other large power tools.

1.8.1   Decommissioning Knob-and-Tube Wiring

Decommission knob-and-tube wiring before or during weather­ization if possible. Try to convince your clients or their landlords to replace knob-and-tube wiring with their own funds.

Use a non-contact voltage tester to determine whether the knob-and-tube wiring is live. If you’re unsure about whether the wiring is still live, schedule an inspection by an electrician.

If the knob-and-tube wiring in an attic is live, ask an electrician and/or an electrical inspector to determine whether the attic wiring can be decommissioned and replaced with non-metallic (NM) sheathed electrical cable. Depending on the situation, the electrician may choose one of these two options.

1.      Terminate the existing attic knob-and-tube wiring, and connect the new NM circuit directly to the main ser­vice box.

2.      Install a flagged junction box in the attic to connect the knob-and-tube riser to new NM cable in the attic.

Consider installing a hard-wired CO/smoke detector in a com­mon area near the bedrooms on the new circuit.

1.8.2   Constructing Shielding for Knob-and-Tube Wiring

You may install attic insulation up to the bottom of knob-and-tube wiring, but never cover knob-and-tube wiring with insula­tion that covers the wires.

✓     Construct structural dam to maintain a 3-inch clearance between attic insulation and knob-and-tube wiring. Don’t cover the knob-and-tube wiring.