posted 10-13-2004 08:17 PM                 

quote: Steve Guttag

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...grounded...a particularly good safety feature for a toaster...especially if you plan on having your toast while taking a bath...

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quote: Steve Guttag

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It would appear that Phil's toaster had the same line of thinking.

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Gosh Steve, since I don't take a bath ..and I DON'T stink cuz I take showers... I would NEVER think about taking a toaster near a bath... only a shower.

YES! Earth/safety grounds are good!

>>> Phil

posted 10-18-2004 12:30 PM                       

quote:

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The second kind of ground is equipment grounding. This is accomplished when all metal frames of equipment and enclosures containing electrical equipment or conductors are grounded by means of a permanent and continuous connection or bond. The equipment grounding conductor provides a path for dangerous fault current to return to the system ground at the supply source of the circuit should an insulation failure take place. If installed properly, the equipment grounding conductor is the current path that enables protective devices, such as circuit breakers and fuses, to operate when a fault occurs.

GROUNDING PATH

The path to ground from circuits, equipment, and enclosures shall be permanent and continuous.

This requirement was extracted from NEC 250-51, Effective Grounding Path, which is more complete and fundamental to the understanding of electrical safety. It states that the path to ground:
"shall be permanent and continuous." (If the path is installed in such a way that damage, corrosion, loosening, etc. may impair the continuity during the life of the installation, then shock and burn hazards will develop.)

"shall have capacity to conduct safely any fault current likely to be imposed on it." (Fault currents may be many times normal currents, and such high currents may melt or burn metal at points of poor conductivity. These high temperatures may be a hazard in themselves, and they may destroy the continuity of the ground-fault path.)

"shall have sufficiently low impedance to limit the voltage to ground and to facilitate the operation of the circuit protective devices in the circuit." (If the ground-fault path has a high impedance, there will be hazardous voltages whenever fault currents attempt to flow. Also, if the impedance is high, the fault current will be limited to some value so low that the fuse or circuit breaker will not operate promptly, if at all.)
It is important to remember the following regarding safe grounding paths:
The fault current in A-C circuits will be limited by the sum of resistance and reactance, and the only low-reactance path is that which closely follows the circuit conductors.

If a metallic raceway system is used, make sure that the metallic system is continuous and permanent.

In cases where a metallic raceway system is not used, provide a green or bare equipment-grounding conductor close to the supply conductors to assure that all enclosures are bonded together and to the source.

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