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SAFETY MODEL STAGE 3—CONTrOLLING HAZArDS: SAFE WOrK ENVIrONMENT

bonding jumper—the conductor used to connect parts to be bonded

box, might not make a good electrical connection because of paint or possible corrosion. To make a good electrical connection, a bond- ing jumper needs to be installed.

A metal cold water pipe that is part of a path to ground may need bonding jumpers around plastic antivibration devices, plastic water meters, or sections of plastic pipe. A bonding jumper is made of conductive material and is tightly connected to metal pipes with screws or clamps to bypass the plastic and assure a continuous grounding path. Bonding jumpers are necessary because plastic does not conduct electricity and would interrupt the path to ground.

Additionally, interior metal plumbing must be bonded to the ground for electrical service equipment in order to keep all grounds at the same potential (0 volts). Even metal air ducts should be bonded to electrical service equipment.

Control overload current hazards

When a current exceeds the current rating of equipment or wiring, a hazard exists. The wiring in the circuit, equipment, or tool cannot handle the current without heating up or even melting. Not only will the wiring or tool be damaged, but the high temperature of the con- ductor can also cause a fire. To prevent this from happening, an overcurrent protection device (circuit breaker or fuse) is used in a circuit. These devices open a circuit automatically if they detect cur- rent in excess of the current rating of equipment or wiring. This excess current can be caused by an overload, short circuit, or high- level ground fault.

Use overcurrent protection devices (circuit breakers or fuses) in circuits.

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Section 7

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