Wiring and Grounding - Internal

Anytime sensitive loads are used, great care should be taken to ensure the wiring and grounding are appropriate. Every aspect of the power system should meet, or exceed, the National Electrical Code requirements. It is important to realize that the Code is not concerned with power quality, rather its concern is with safety.

With respect to computer restarts and lock-ups, grounding is often a key ingredient to problems. The ground of the ac power is used by the electronic device as its digital reference. Noise and transients can travel along the ground and enter the device, disrupting proper data flow. This disruption usually results in a lock-up.

If local area networks (LANs) are in use, grounding is even more important. As mentioned a moment ago, the digital reference of PC #1 on the LAN is the outlet it is plugged in to. The same applies to PC #2. If a voltage difference exists between these two ground points, then current will flow through the data cable connecting the two PCs. This can disrupt data flow and cause lock-ups also.

If wiring is found that violates the Code, it should be fixed immediately. Oftentimes, 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.

When 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.

Using ground rods for grounding sensitive electronic devices inside the building is not recommended.