Electrical Testing
Tip of the Week: It’s T&M Quiz Time TimHesterPhotography/iStock/Thinkstock

Tip of the Week: It’s T&M Quiz Time

Choose the proper PPE when measuring voltage

True or False: If you’re working on 120V circuits, you don’t need PPE just to take a voltage measurement with your DMM.

Answer: False.

A trickier question is this: Exactly what PPE do you need, at least as a minimum? You’ll find the answer in NFPA 70E, Table 130.7(C)(16).

This table provides PPE requirements for four different PPE categories. The category you need to apply depends upon the voltage level and the task you are performing. You can use Tables 130.7(C)(15(A)(a), 130.7(C)(15(A)(b), and Table 130.7(C)(15(B) to find the correct arc flash category for the work being done in a given environment. In this case, it’s PPE Category 1.

So, what are the requirements? Regardless of the PPE category, the required PPE includes:

  • Safety glasses (or, if a splash hazard, safety goggles).
  • Hearing protection
  • Hard hat
  • Leather footwear.

Looking at the requirements in Table 130.7(C)(16), you find you also need clothing with a minimum arc rating of 4 cal/cm squared. That includes a long-sleeve shirt, face shield, and other items. Plus, you need heavy-duty leather gloves.

The PPE is not your first line of defense, however. Some other tips to follow:

  • Use test equipment from a recognized, reputable manufacturer. A cheap knockoff may have construction deficiencies not found in major brands, and those could cost you your life.
  • Don’t use damaged test leads.
  • Follow the one-hand rule; use only one hand at a time on test leads rather than holding a lead in each hand.
  • Know what you’re measuring. If you “think” it’s 120V and it’s actually a medium-voltage system as the label above it says, both you and the meter could be toast.
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