You meet with your top guns, and everyone agrees there is obviously a root cause, or this many failures wouldn't happen on the same day. One of your people says, "Well, we can rule out rain. It hasn't rained for several days." What is the likely problem, and how should you hunt it down?

Replacing Cables
With a cable-testing program, you will very rarely -- if ever -- see cable failure. Instead, you will see cable deterioration -- and you repair or replace cables before they fail. Here are some tips on replacing cables effectively:

1. Determine the cause(s) of deterioration. A qualified testing firm is an excellent resource for assistance with this. Cables do deteriorate due to age, but don't assume that's the cause. Many things can accelerate insulation degradation.
2. Evaluate the cable for the application. Before replacing a cable, consult your supplier with the details of the application and get a recommendation for the type of cable to use. Your application may have changed since the original installation, or a better cable may now be available.
3. Review routing and mechanical protection. Because you'll disturb raceways and physical cable bundling to replace an existing cable, think carefully about how you want to put things back. For example, you might relocate motor drive cables away from the general use feeder cable tray.
4. Prepare for proper installation. When production is down, you don't have time for installation tutorials. The crew must know the correct methods in advance. The wrong methods can cause premature failure. Exceeding a bend radius or maximum pulling tension, for example, reduces the life of the cable. Following the specific installation procedure for a specialty cable may greatly extend the life of the cable.

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NEC at the Facility
An overcurrent protection device (OCPD) must have an enclosure to protect it. Article 240, Part III addresses OCPD enclosure requirements. But these are for protecting the OCPD, not for protecting people operating it. You must go beyond Article 240, Part III to have a safe enclosure installation.

A common problem is an enclosure installed without adequate room on the right-hand side. For example, the panel is too close to a corner. This forces you to stand in front of the enclosure to operate the OCPD (which, presumably, you do with the left hand). When are breakers most likely to explode? When they're being operated. Where do you want to be when that happens? Not in front of the breaker, that's for sure.

Install OCPD enclosures so people can operate the OCPDs without standing directly in the blast path. Manufacturers are excellent sources of advice, anytime you add OCPDs or an enclosure.

The Practical Implications of OSHA 1926.405
You may have heard, "We aren't required to follow the NEC inside our facility." This may be somewhat true if the Authority Having Jurisdiction (AHJ) granted exceptions for the installation of conductors and equipment [90.2(C)]. However, OSHA puts those requirements right back in place. The reason is very simple. NEC requirements -- based on the laws of physics -- attempt to answer the question, "How do we protect people and property?" OSHA attempts to protect people.

Thus, OSHA 1926.405 poses requirements you also find in NEC Chapter 3. Consequently, violations of Chapter 3 wiring methods can result in far more than a fine from the local AHJ. OSHA fines are possible. But so is personal criminal liability, in the event of a tragedy.

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Quiz Answers
Answer to Electrical Troubleshooting Quiz
The fact this is occurring on such a wide scale in so many systems indicates there is a root cause. The most likely cause is cable insulation deterioration. The observation that "it hasn't rained for several days" is a good clue -- you had rain just a few days ago. This means rainwater had time to make its way into raceways and form a conductive path between the cable insulation and ground.

Under dry conditions, the leakage from the cable goes unnoticed. But when water enters the raceway, that leakage increases dramatically -- you get low voltage and other symptoms. The leaking electricity boils off the water, causing these problems to "magically" disappear until the next incursion of water.

To fix this, you start with a one-line diagram of your facility and thoroughly test all of the cables in each drill-down from your one-line. If you test just "major" cables, you may not increase uptime because another cable failure will still shut you down. However, you'll need to weigh that consideration against the possibility of a catastrophic cable fault at the service or feeder level. A qualified testing firm can help you develop the best approach for your situation.

See our tips for cable replacement, above. As you replace bad cables, carefully examine the installation for ways to reduce water incursion.