|  | 8.10 | Network Power Supply Issues: Power Line Problems
| 8.10.6 | Surge and spike solutions

A common solution to the problem of surges and spikes is the use of surge suppressors. Theoretically, when surges or spikes come in, surge suppressors divert them to ground. In actual practice, however, it has been found that spot placement of surge suppressors can increase the incidence of electrical problems. For example, if equipment is not properly grounded when a surge suppressor channels a surge to ground, it actually elevates the ground potential. The resulting differences in ground voltages can create electrical current that flows in the ground circuit. Current flowing in a ground loop can damage non-protected devices; therefore, in any LAN installation, a good rule of thumb to follow is to protect all networking devices with surge suppressors.

If your network is attached to a telephone line for modem or fax use, it is important that the telephone line be surge protected also. This is because lighting strikes to telephone lines are not uncommon. Even lightning spikes across the telephone lines to unplugged networking devices have been known to destroy components. As a general rule therefore, consider the telephone line to be part of the network. If you protect one networking device with a surge suppressor, then you should protect all devices, including the telephone line, in the same way.