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:
“Like art, revolutions come from combining what exists into what has never existed before.”
—Gloria Steinem (b. 1934)
“I feel the carousel starting slowly
And going faster and faster: desk, papers, books,
Photographs of friends, the window and the trees
Merging in one neutral band that surrounds
Me on all sides, everywhere I look.”
—John Ashbery (b. 1927)
“Heavily hangs the broad sunflower
Over its grave i’ the earth so chilly;
Heavily hangs the hollyhock,
Heavily hangs the tiger-lily.”
—Alfred Tennyson (1809–1892)