Combining Neutral With Earth
Stray voltages created in grounding (earthing) conductors by currents flowing in the supply utility neutral conductors can be troublesome. For example, special measures may be required in barns used for milking dairy cattle. Very small voltages, not usually perceptible to humans, may cause low milk yield, or even mastitis (inflammation of the udder). So-called "tingle voltage filters" may be required in the electrical distribution system for a milking parlour.
Connecting the neutral to the equipment case provides some protection against faults/shorts, but may produce a dangerous voltage on the case if the neutral connection is broken.
Combined neutral and ground conductors are commonly used in electricity supply companies' wiring and occasionally for fixed wiring in buildings and for some specialist applications where there is little alternative, such as railways and trams. Since normal circuit currents in the neutral conductor can lead to objectionable or dangerous differences between local earth potential and the neutral, and to protect against neutral breakages, special precautions such as frequent rodding down to earth (multiple ground rod connections), use of cables where the combined neutral and earth completely surrounds the phase conductor(s), and thicker than normal equipotential bonding must be considered to ensure the system is safe.
Read more about this topic: Ground And Neutral
Famous quotes containing the words combining, neutral and/or earth:
“The wilderness experiences a suddent rise of all her streams and lakes. She feels ten thousand vermin gnawing at the base of her noblest trees. Many combining drag them off, jarring over the roots of the survivors, and tumble them into the nearest stream, till, the fairest having fallen, they scamper off to ransack some new wilderness, and all is still again.”
—Henry David Thoreau (1817–1862)
“The lonely Earth amid the balls
That hurry through the eternal halls,
A makeweight flying to the void,
Supplemental asteroid,
Or compensatory spark,
Shoots across the neutral Dark.”
—Ralph Waldo Emerson (1803–1882)
“Earth laughs in flowers, to see her boastful boys
Earth-proud, proud of the earth which is not theirs;
Who steer the plough, but cannot steer their feet
Clear of the grave.”
—Ralph Waldo Emerson (1803–1882)