Article 110 provides general requirements for all installations. Circuit protective devices need to clear a fault without extensive damage to the electrical equipment of the circuit. The NEC wants designers and installers to permit this, so Sec. 110.10 requires you to select and coordinate the following:
- Overcurrent devices.
- Total impedance.
- Equipment short-circuit ratings.
- Other characteristics of the circuit to be protected.
This last item on the list seems vague, and the NEC gives no examples. That is intentional, because the NEC is not an instruction manual for untrained persons [Sec. 90.1]. The idea is that you look for anything that might prevent circuit protective devices from clearing a fault without extensive damage to the electrical equipment. And once you find it, correct for it.
If you are going to use conductors or equipment in any of the following operating environments, they must be identified for use in the specific environment [Sec. 110.11]:
- Wet or damp locations.
- Where exposed to gases, fumes, vapors, liquids, or other agents that have a deteriorating effect.
- Where exposed to high temperatures.
Any equipment not identified for outdoor use must be protected against damage from weather during construction.
From the preceding requirements, it follows that you can’t use paints, lubricants, or solvents that are not identified for use with the materials that the conductors or equipment are made of. For example, a popular lubricating oil that comes in a spray can gives a nice sheen to the black jacket of a conductor. But that jacket will deteriorate from the exposure. Never apply any kind of oil to any kind of rubber or similar compound. If you need to clean anything electrical, use a product identified specifically for that purpose.
