Power System - Multiple Buildings

The fact that many businesses are housed in multi-building facilities makes matters more complex because each building may not have its own service entrances. Some may be fed through outdoor branch circuits from these buildings. In these situations, grounding and voltage stability become key areas of concern.

If data communication between buildings is required, then the use of modems, or better yet, fiber-optic cables, will prevent ground loop problems. If modems or direct cable connections are used, be sure to provide data line transient protection.

Where modems or direct cable connections exist, take care to minimize picking up high frequency interference (commonly called EMI) on the signal or ground conductors, or on the outer cable shield itself. This, coupled with grounding concerns, can become so troubling that many experts strongly discourage using direct cable connections between buildings.

If wiring is found that violates the Code, it should be fixed immediately. Often, bringing the electrical system up to Code resolves many power quality problems.

If poor grounding is a concern, the use of isolated ground receptacles, isolated ground busses in the panel, and isolated ground conductors will alleviate most problems.

If an isolated ground conductor is used, it should be run in the same raceway as the power conductors, and terminated at the neutral-to-ground bond of the power source. This source is the transformer or service entrance directly feeding the loads.

Ground rods are not recommended for grounding sensitive electronic devices inside the building.