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PTO Generators Observations
"The ground wire is a moot point since one conductor cannot form a circuit, especially when it's grounded anyway."
Murf are you saying in Canada the ground is separated from the neutrals. Here they are all together, which would make sense as to why you thought the neutrals could be more dangerous(not being grounded) like they are here.
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PTO Generators Observations
No the neutral leg is bonded to the ground here also.
However, as I'm sure you are painfully aware, electricity takes the path of least resistance. If there is a bach-feed situation there is a 220 V. potential on the neutral out to the transformer which will, as mentioned, step it up to line voltage.
If an unsuspecting linesman becomes the conductor to complete the circuit he gets a big poke.
Thats why the neutral MUST be disconnected here to prevent potential back-feeding of the grid.
Best of luck.
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Here is a BIG wrinkle:
I have a regular breaker box / load center. Coming into the house are 3 wires from the utility co, 2 hot (L1 and L2) and one neutral, neutral is bonded to ground at the load center. Potential difference is 110 V between each hot line and neutral and 220V across the two hot lines. The main switch (labeled MAIN PRINCIPAL) opens connectors on L1 and L2, neutral / ground have no switches to disconnect and are hard wired to the utility co. I bought a generator transfer switch (GE - reputable brand). I opened it up and guess what it does, it only disconnects L1 and L2, neutral / ground is routed straight through with no opportunity for disconnection. It seems to me the transfer switch only limits or chooses which individual circuits to energise and opens contacts on L1 and L2. In theory this identical setup can be achieved by opening the main principal switch on the panel, plugging a male electricity source from a generator into a dryer outlet and opening individual branch circuits you do not want energized. Bar saftey and code issues (yes these are important) can anyone describe how the two setups are FUNCTIONALLY different?
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There is absolutely no difference, that's exactly the problem.
It is so easy and simple that most people do it exactly that way, make up a cord with a male plug on each end and away they go.
In some areas it is even borderline legal.
However, it is not safe or smart.
It is also difficult to balance the load properly doing it that way since it is purely chance which side of the supply the load happens to be on.
Best of luck.
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If you are talking about the ge transfer swithch i think you are it will only let you get power from one soures at a time. it would be machanicaly imposiple to apply power from two dirrerent sources. As far as disconnecting the neutral the reason why you don't see neutral disconnects here in the US is because it isnt cost effective to have them on the shelves if they are not needed. If Canada requieres it then the supply house will carry them.
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So if the neutral line is not disconected in the transfer switch it is still possible to back feed the Utility co transformer when an unbalanced 220V load is applied to L1 and L2 of the generator. Neutral will carry the unbalanced load and since this line is not isolated from the utility Co it will transfer it to the grid. In this case the use of a transfer switch does nothing to prevent this potential hazard?
FYI For clarity I am not speaking about having L1 and L2 connected to BOTH the generator and the grid at the same time, these would be isolated by the transfer switch or the main if the male - male plug was used.
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For those of us in the USA the NEC (national electic code) is the governing publication for installation of electric facilities.
By definition, Art. 100, Switch, Transfer is "An automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another". As someone has already stated, this means you break one source before make of the other source.
Additional information on generators, standby power systems, etc can be found in Art 230, 445, 700, 702, & 705 in the NEC. You should be able to acquire a copy at your local library.
This is the only way to connect a generator and be safe for all parties involved. Dave
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Steve, I suspect that it is as you say, also the NEC in the US doesn't require it. They assume that the electric utility has done it's job and everything at the transformer, etc., is wired the way it's supposed to be. That is a potentially fatal assumption.
Say for example the power outage, the reason for running the genset, is a result of a lightning strike. If the lightning strike destroyed the neutral conductor on the primary side of the transformer then you could have not only substantial potential on the lines, but you could in fact also have lit up any telephone or cable TV wires that not well grounded, even if they are well grounded they could form a return for the primary circuit.
Try searching on Google or Yahoo for "stray voltage" or "stray current", there is mountains of data out there on this subject.
Best of luck.
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After twenty years i have found no proplems with any of the UL approved devices for tranfering power. Now power does return on the neutral but it returns to the source. Also the neutral does not go thruogh the transformer and if you look each house and transformer and most power poles have a grounding wire , which are attached to ground rods or metal pipes going into the earth. if needed i could get into thearoy but we dont have enuogh time for that.My thought is if you hier a good electrician if it is wrong its his fault, also here in NH the power companys will only let you install certain transfer switches
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Steve4300, I have been sitting here wondering why Canada would put an extra transformer on the neutral line so that a mistaken backfeed could be stepped up to make an even bigger problem. If our utility companies start putting transformers on neutrals that carry no current, I will know they are charging too much for electricity.
I am also still wondering how a properly installed transfer switch balances a load that an unsafe hookup fails to do. No breakers changed position at my house. Electrically speaking, isn't feeding both poles at the top of the panel the same as feeding both poles anywhere along them? Just like placing a breaker at the top will result in the same usable power as placing it at the bottom.
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01-26-2005, 08:12 
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