Interlock locks to be used in lieu of transfer switch

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I have this generator:
http://igor.chudov.com/tmp/onan/Diesel /
I bought these interlocks on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item00106024488
They are actually quite large, the photo does not do them justice.
My plan is to place interlocks so that either the generator's disconnect is closed, or the main panel breaker is closed, but never both.
That's what they were designed for, if it is unclear to anyone, I can explain it in more detail, or see: http://www.kirkkey.com/index.html
I would lock up another key (they are keyed alike) in my safe so that its use cannot defeat this system.
I believe that this arrangement fully satisfies the rule that a mechanical interlock device should prevent both sources of power from coming in contact.
Any comments?
i
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Ignoramus23720 wrote:

I don't think your local inspector is likely to approve of such a setup. You would be better off with an approved interlock system produced by the manufacturer of the electrical panel such as the Square D setup I use.
Pete C.
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Ignoramus23720 wrote:

AT&T had this arrangement on a battery plant that was in two cabinets. The interlock depended on one key that had to turned to release the key so it could be used in the other cabinet..
So some idiot had a spare key made so he didn't have to move the key. Some time later he disconnected both battery strings and failed the service.
Not much is idiot proof
Bill K7NOM
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Not acceptable.
Currently approved mechanical interlock devices physically do not permit both breakers to be on.
With this, a second key already exists, and if it did not, a hardware store could make one - nothing to prevent both from being turned on at once, other than the assumption that there's only one key. A key in a safe can be removed from a safe, a key in place can be copied. Your taste for weird old surplus has got the better of you - there's a reason this stuff is surplus.
--
Cats, coffee, chocolate...vices to live by

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On Mon, 07 May 2007 18:05:13 -0500, Ignoramus23720

It's a perfectly acceptable solution and I've used it on power station transfer boards.
Regards Mark Rand RTFM
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Mark, thanks. To answer other people's concerns, I am not going to duplicate the keys. I think that to prevent use of the second key, I may simply put both keys on one steel "connecting link" (a shackle used to connect chains) and will weld the link shut so that they cannot be separated. Or else I will bolt it to a wall in some secret location or save it in the safe.
These interlock keys are indeed used relatively widely in industry for all sorts of purposes. See the kirkkey.com website for examples.
i
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Ignoramus3938 wrote:

A power station which is presumed to be accessible only to qualified persons. A residential setting which is presumed to be accessible to unqualified persons. Your interlock may well be acceptable in a power station, it will not however be acceptable in a residence. Inspection requirements and codes applicable are also very different between residential (NEC) and power station (NESC).
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Yes but many of these "Kirk key" locks have keys that cannot be duplicated easily.
wrote:

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Mark Rand wrote:

Mark I don't know were you or the OP are located so I'll answer as if both of you are in the United States. It may indeed be acceptable in a power station that is operated by a utility under the National Electrical Safety Code (NESC). The NESC is the code that is enforced by the public utility regulatory bodies in most states to govern the installation and operation of electrical generating and distribution systems. It is not however compliant with the National Electric Code (NEC) that is adopted and enforced as law by the vast majority of local or state governments in the United States. The NEC is also incorporated by reference into the vast majority of insurance contracts in the US. The NEC requires that materials be approved by the Authority Having Jurisdiction (AHJ). The AHJ can be the local building official, electrical inspector, or the insurance companies loss prevention department. No responsible AHJ will approve the use of an interlock that is not listed by a national electrical testing laboratory.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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wrote:

some people will do endless work to save a buck but create possible hazards later. The OP asked his question so posters could agree, and must be disappointed so many dont.........
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Ditto in Canada. It's permitted under the CEC, but not in residential setups. In a residential situation, I do not believe that an inspector would approve _anything_ like that that didn't have a full CSA approval for the specific purpose.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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I suppose that being a somewhat ethical and caring person, and like the KISS principle (Keep it Simple Stupid), I would have to go with the tradition 3-pole, 3-position, transfer switch. On these, one position puts your home on grid power, in the center postion it is connected to nothing, and in the thrid position it is connected to your generator.
Only a week or two ago I was running my home on generator power, with the generator connected to the house with a "suicide cord", and the master breakers to the house pulled. I went outside and spent some time talking with the line crew that was replairing the down line in front of my home, in the rain. Having noticed that I was running a generator, one of the guys asked me if I was sure that I was disconnected from the grid. I replied that I knew I was, because the breaker connecting me to the grid was not only turned off an pulled, so I could see about 2-3 inches of physical separation.
No problem, he replied to me, and also informed me that the top like supplying the transformers on my street was an 8,000 volt line. I'm not a lineman but am an electrical engineer, and would not sleep at night if I were risking backfeeding a distribution transformer that stepped the voltage up to 8,000-volts, or even 2,200, no matter how clever the interlocking arrangement. I am not that desperate to power my home, and as an engineer I recognize the too frequent failure of such arrangements, let alone to build one myself. It's not so much the design of such interlocks, but the failure modes that amateur designers often fail to take into account, with tragic consequences.
Harry C.
On May 7, 7:05 pm, Ignoramus23720 <ignoramus23...@NOSPAM. 23720.invalid> wrote:

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Especially the retarded lineman that doesn't use equi-potential technique grounding devices to protect himself from induction and static charges that exist on lines running accross the countryside just by laws of nature. Your little generator is not a problem for any lineman that isn't a lazy and lucky jerk.
Interlocks are still necessary to help prevent frying the lazy and lucky jerk though. You are right. You don't want to run the child over, green light or not.

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Waht about the casual bystander or neighborhood kid who doesn't notice the house-end of your feed lying in the dirt?
--
Chris Lewis,

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If the house end of the conductors are lying in the dirt then your service is disconnected and can't feed anything and the kid has to worry about the utility power instead.

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If you're backfeeding, you have a lethal boobytrap lying in the dirt.
Worse if it's upstream of the last polepig.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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That might be but stop using the trained lineman as an excuse to put proper interlocks in your generator/grid tie-in. It's just crap.

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_I_ wasn't. Backfed wires are a hazard to everyone. Linesmen are just one.
Even trained linesmen get tired, make mistakes, or just get zapped by something unforeseen.
You have an ice storm that takes out power for weeks. The crews are dead tired. There's wire draped over _everything_, buried under snow and ice. Linesmen are hanging out the side of helicopters 200' up at -40F and strong winds (not to mention the windchill factor from the helicopter itself!) trying to repair HT lines. The army is out dragging out power poles and the remains of high tension towers, rescuing people from frozen homes, stuck cars, and houses filled full of CO. Everybody is just trying to survive and get the job done as quickly as possible.[+]
How do you think they'd feel about idiots backfeeding?
Then is not the time to set booby traps. It's just stupid. Do it right.
There's a special place in hell reserved for those who endanger emergency crews or steal emergency equipment during an emergency.
[+] Great ice storm of 1998. I helped out in that. Inspecting/doing generator hookup in homes and emergency depots. You better believe we were careful making it _impossible_ for backfeed to occur.
--
Chris Lewis,

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On Fri, 11 May 2007 13:53:02 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

Has everybody missed the point that fitting proper interlocks is _precisely_ what Iggy is proposing to do? OK he's not buying a nice idiot homeowner retail kit from home-generators_R_us. He is engineering a solution that is at least as foolproof and effective. Good luck to him!
Mark Rand RTFM
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It doesn't appear to have enough poles to be effective - it doesn't switch both sides of the panel. Secondly, it's probably not approved for the purpose of switching residential feeds, and there may well be a reason why it wouldn't be.
To do it right is to do it within the NEC (or CEC) with devices UL or CSA-approved for the purpose, or be able to find an electrical engineer who is willing to sign off on it.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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