After purchasing a gaussmeter, an electrician was surprised to discover an elevated magnetic field throughout his entire driveway and a portion of his home. Upon learning that the field did not decline when he shut off the power to his home at the main breaker, he concluded that the source of the field was from net current in the gas line. A gas company technician visited the siteand confirmed that the gas line was carrying electricity. There was no cause for concern, he said, because the amount of electricity was small.
The electrician was not comforted by such reassurances. As a specialist in complex wiring
techniques for boats and marinas, he was familiar with the problems of electrolysis and galvanic action resulting from electricity straying from its intended path. He had even witnessed boats at the local marina whose metal had gradually dissolved from exposure to net current. Thus, the electrician reasoned, the net current in his plumbing and gas lines would cause the lines to deteriorate at an accelerated rate. After informing the gas company that the galvanic action in the pipes was a liability for the company because of the possibility of an explosion, the electrician was finally able to persuade the them to take his complaint seriously.
Magnetic fields are measured with a gaussmeter. A homeowner might consider purchasing a gaussmeter for one or more of the following reasons:
• to determine safe distances from various household appliances
• to help detect wiring errors that not only produce magnetic fields but also may be fire and electrocution hazards
• as a periodic safety check to determine that no new problems have developed in household appliances
• as a periodic safety check to ensure that no new magnetic fields are entering the home through utility lines
There are two basic types of gaussmeters: single and triple axis. Single-axis meters tend to be less expensive and are slightly more difficult for a novice to use because they must be rotated to align with the flow of the magnetic field in order to detect it. Orienting a tripleaxis meter with a field is not necessary because this meter requires positioning only within the range of the field. Less expensive gaussmeters will give false readings when measuring certain magnetic fields such as those generated by computers and electrically ballasted fluorescent lights. The following gaussmeters are widely available and are generally adequate for measuring household fields:
• MSI EMF Meter is a single-axis meter that is accurate for field frequencies between 60 and 180 hertz but does not measure higher frequency fields.
• Tri-Field Meter is a low-cost triple-axis meter for measuring magnetic and other fields. The meter may overestimate 60- hertz fields because of interference when higher frequency fields can also be detected.
