Operation and Maintenance - hdbk109220040169

DOE-HDBK-1092-2004

10.8.1.3 OPERATION AND MAINTENANCE

Before working in a power-supply enclosure or an associated equipment enclosure, see

Sections 2 and 7. Personnel should take the following precautions:

1. Implement lockout/tagout.

2. Check for auxiliary power circuits that could still be energized.

3. Inspect automatic shorting devices to verify proper operation.

4. Short the power supply from terminal to terminal and terminal to ground with grounding

hooks.

10.8.2 CONDITIONS OF LOW VOLTAGE AND HIGH CURRENT

10.8.2.1 HAZARDS

It is usual for R&D facilities to have equipment that operates at less than 50 V. Although this

equipment is generally regarded as nonhazardous, it is considered hazardous when high

currents are involved. Examples of such equipment are a power supply rated 3 kA at 25 V, a

magnet power supply with rated output of 200 A at 40 V, and a bus bar carrying 1 kA at 5 V.

Though there is a low probability of electric shock at voltages less than 50 V (See Figure 10-1),

there is a hazard due to arcing and heating in case of an accidental fault. For example, a tool

could drop onto the terminals and initiate an arc, causing severe burns.

10-6