Wayne Dohnal
Banks, OR.
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The Wikipedia article also states that the single wire systems operate at 13 or 19 kilovolts, and the power goes through a step down transformer before entering the customer premises, using the standard 3-wire hookup for 240v split phase service. The earth is NOT used to carry power to the customer.
2009 Fleetwood Icon 24A
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Deus Ex Machina
Central New Jersey
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Wayne Dohnal wrote:The earth is NOT used to carry power to the customer.
Of course, absolutely never. It is only used in high tension applications.
Paul
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Old & Slow
Texas
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smkettner wrote:Deus Ex Machina wrote:So he most certainly DOES know what he's talking about. You will often see this in isolated areas, just a single hot wire along the top of the poles, and that's it.
Here is one article documenting it. It is call SWER (Single Wire Earth Return).
(Hmm, why did that laughter suddenly stop?  )
Did you read the article? The system failed to work in the mid 1800s
Does it exist today? Not a chance.
The novice must jump in here. I lived for a number to years in third world countries with two wire 240vac systems ( two hots). Not safe but used. If you wanted 120v. you just used one wire and a really good ground, like a rod in the ground or if a water system was is place, attach ground wire to pipe. I know we are talking USA and Canada here.
* This post was
edited 11/07/09 08:16am by Old & Slow *
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john&bet
North Vernon,in.
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In the artical in the wiki. link it looks to me as though the grounded conductor is tied to the second wire down on the pole. In front of my house there are 4 wires on the poles. 3 hot( 3 phases) 1 nuetral which is connected to the sub station transformers 1200' from my house. There is 4 wires feeding the substation as part of the grid system. If you are going to get multi votl legs from a transformer there has to be a nuetral tap on that transformer( grounded conductor) somewhere and is usually bonded to the grounding system. I thought Wiki was just everyboby opinion on how things worked, not pure science.
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wa8yxm
Wherever I happen to park
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There is one reason. IN theory, to ground a generator I had not thought of prior to just now (Thanks HWYBNB)
However I"m not sure if ground will help or not
Static Electricity v/s fuel vapors
Anyone care to comment on this issue? As I said. I have not the data handy to comment. but my thinking is if either the Generator, or the operator builds up a static charge... At re-fueling time.. Bad things might happen.
NOTE: even if it's grounded. if the operator bulids up a static charge... Same thing.
Nothin adds excitment like something that is none of your business
Kenwood TS-2000 housed in a 2005 Damon Intruder 377
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vermilye
Oswego, NY, USA
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Quote:Common use is stretching it rather far. It is against the NEC according to the Wikipedia article except by special consideration and exemption. At some point it would appear a system was installed in extremly remote areas of Alaska where the only alternative was local diesel generators. First point - the utility companies are not covered by the NEC. For example, if they were, in most cases the overhead wiring leading to your house would be considered undersized.
Second, the single wire distribution system is alive & well in places other than Alaska. National Grid uses it in parts of Upstate NY, for example, here in Oswego county. If necessary, I'll go out & take a photo, but I have seen this system in a number of areas along Lake Ontario. It is used to distribute single phase 13KV high voltage. At each transformer, the single high voltage wire goes to one input & a ground (usually a plate buried under the pole) goes to the other. The typical output of the transformer would be a center tapped 120/240v 3 wire (hot, hot, and neutral) feeding a home. There is no ground wire - grounding takes place at the service entrance panel in the home.
As to the original post on grounding generators, you might want to take a look at this article by John "Grizzy Grzywacz for some facts, examples, and suggestions on both grounding & bonding of portable generators.
Jon Vermilye Travel & Photo Web Pages ... My Collection of RV Blogs & Journals
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hwybnb
Southern California
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I believe it has been established that there are single-wire distribution systems in existence but they are irrelevant to this discussion. They are very few in number and more to the point, the residential consumer never interfaces directly with them.
This discussion is about ground rods and their applicability to portable generators. Here is a summary of the requirements that pertain to portable generators per OSHA,US Department of Labor Code of Federal Regulations (CFR). Bonding and GFI requirements have been included for completeness:
Grounding
29 CFR 1926.404(f)(3) allows the generator to operate without a ground rod under the following conditions:
(1) The generator supplies only equipment mounted on the generator and/ or cord and plug-connected equipment through receptacles mounted on the generator, and
(2) The non-current-carrying metal parts of equipment (such as the engine, and the generator’s housing) are bonded to the generator frame, and the equipment grounding pins of the power receptacles on the generator are bonded to the generator frame
Ground rods are not required when generators meet these requirements. The Honda EU1000/2000 and similar machines do.
Neutral Conductor Bonding
29 CFR 1926.404(f)(3)(iii)
A neutral conductor shall be bonded to the generator frame if the generator is a component of a separately derived system. The definition of "separately derived system" is complex but a portable generator that supplies power to a cord-connected RV is one.
Neutral Bonding is required
Thanks to Larry Cad for help on that one.
GFI
29 CFR 1926.404(b)(1)(ii)
Recepticals of a two-wire, single-phase portable or vehicle-mounted generator rated at no more than 5 kW, where the circuit conductors on the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground fault circuit interrupters. The reference to two wires does not including grounding conductors.
GFI protection is not required
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vermilye
Oswego, NY, USA
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Quote:A neutral conductor shall be bonded to the generator frame if the generator is a component of a separately derived system. The definition of "separately derived system" is complex but a portable generator that supplies power to a cord-connected RV is one. But, to add a bit more confusion - You only have a neutral in a dual voltage system (ie a 120/240 volt generator). Since many of the generators we are using for powering RVs are single 120v devices, there is no neutral & bonding is not required.
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Salvo
California
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GFI protection isn't required because it wouldn't provide any protection. GFI = Ground Fault. Since there is no Ground connection (the Ground is not bonded and therefore is floating), there can not be any ground faults. Hence no need for GFCI.
Sal
hwybnb wrote:
GFI
29 CFR 1926.404(b)(1)(ii)
Recepticals of a two-wire, single-phase portable or vehicle-mounted generator rated at no more than 5 kW, where the circuit conductors on the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground fault circuit interrupters. The reference to two wires does not including grounding conductors.
GFI protection is not required
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Old & Slow
Texas
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I am aware this discourse is between men of learning. You have to know us folks in the novice class read this thread with interest, BUT only to find the truth if our Gensets are safe for use with our RV's. I have a Champion C46540 120/240v with a switch for 120v use only. The TT30R has a floating neutral. The G/Y third connector in the RV recp't runs to the RV cord and to the RV. Then is this setup considered a 120v two wire system and forget that the genset can produce 240v? And no GFI needed?
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