How do you correctly determine what PPE you need to take a voltage measurement on an energized 480V circuit? That depends upon the equipment.
Let’s say it’s a panelboard. To find the answer, you’ll need to look in three tables:
- Table 130.7(C)(15(A)(a)
- Table 130.7(C)(15(A)(b)
- Table 130.7(C)(16)
Start with Table 130.7(C)(15(A)(a) and look for the task. Fortunately, it’s in the third row rather than near the end of this large table. What we find is that for equipment in any condition, Arc Flash PPE is required when taking a voltage measurement in an AC system.
If you look in the row above this one, you will see an example of an activity that does not require Arc Flash PPE. That activity is the closing of a circuit breaker, switch, contactor, or starter if everything about it is known to be good (installed correctly, properly maintained, etc.). If you were troubleshooting this equipment, you would need Arc Flash PPE because there may be a problem with it. If you’re unsure about “good,’ err on the side of protecting yourself. There’s no harm if you wear PPE when you don’t need to, but the same cannot be said of not wearing it when there’s a need.
Now you know you need Arc Flash PPE. To determine which Arc Flash Category it must be rated for, go to Table 130.7(C)(15(A)(b). Now look for the equipment in question. It’s in the second row (we lucked out again). Your PPE must be rated for Category 2.
Turn to Table 130.7(C)(16), and you see the requirements for PPE Category 2. Beyond the PPE required regardless of the PPE category (look at each category and you’ll see certain items repeated), you also need clothing with minimum arc rating of 8 cal/cm2.
The clothing includes long-sleeve shirt, flash suit hood or arc-rated face shield, and other items.