richard nute

Product markings and labels provide information about the product, installation, and use. The markings and labels can also provide warnings to avoid hazardous energy transfer to a body part. The product safety aspects of markings for identification, ratings, functions, connections, and warnings are described.

Can the hi-pot test and the insulation resistance test be combined into a single measurement? Let’s discuss each of these parameters as circuit parameters and as safety parameters.

For production-line testing, the 25- or 30-amp grounding continuity test is not likely to identify construction anomalies that would not also be identified by a simple low-current test.

High-current grounding impedance tests have been specified in safety standards for many years. There are two, independent sources for these tests.

There always seem to be questions about hi-pot testing. Maybe I can present some of those questions and their answers.

How does safety work? That is, given a hazardous situation, how do we prevent injury from that situation?

Did you ever wonder why we use 0.1 ohm (and sometimes 0.5 ohm) for the ground impedance value for plug-and-socket connected equipment?

The “power distribution system” is all parts of an electric system between the “bulk power source” and the consumer’s service-entrance equipment.

Recently, a colleague remarked to me, “Philosophically, of course, there is no such thing as absolute safety.” Could this be true? Is there a situation where a man could not possibly injure himself?

This issue’s topic is rather unique because this column addresses safety requirements for a non-safety critical device, “operational” or “functional” insulation.