| Beachcomber 2006-04-14, 4:21 am |
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First off, let me say that I am no expert in this subject, but I would
like to hear the latest current thinking of the professional
electrical community as to what the current thinking is on this and
if any 20007 NEC code changes can be expected as a result.
Detailed background information on each case is available at the
following links:
Argument in favor of multi-point primary neutral grounding:
http://www.neiengineering.com/pdfs/paper10JN.pdf
Argument in favor of single-point primary neutral grounding:
http://www.mikeholt.com/documents/s...Final5-3-03.pdf
As far as I can determine, the current multi-point primary grounding
system in the US...
1. is favored by most utilities
2. has less expensive capital costs (fewer conductors - insulators -
uses single bushing transformers vs. double bushing, etc.)
3. Perceived as safer to lineman (assured neutral grounding at
multiple points)
4. Easier on transformers (less intense surges and easier to connect
lightning arrestors to).
5. Works better for isolated distant distribution transformers (as
typically found on US farms)
On the downside...the multi-point neutral primary grounding system...
1. Can produce undesirable stray voltages (more properly - stray
currents) under the right set of circumstances. Stray currents may be
harmful to livestock and humans.
2. Can cause shocks in swimming pools and electric showers.
What is the current thinking on this subject? I understand that
Europe bans the multi-point neutral grounded systems, but Europe has
fewer isolated transformers serving distant farmhouses.
Beachcomber
2. Can lead to shocks in swiming pools and electric showers
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