Interlock locks to be used in lieu of transfer switch

May 07, 2007 178 Replies

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.

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.........

Clowns like that guy have an emotional age of about 10.

That should be stamped onto every 'contractor(s)' forehead.

-Carl

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.

According to Solar Flaire :

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

if both you and your wife are in a car wreck, will your executor know to remove it for a house sale, or your long lost cousins move in temporarily?

the point being that you can't ensure removal.

All juristictions are different but where I am I know the response of the building inspector because it is the same response he gives to EVERYTHING he is not familiar with. It is a response borne of sheer necessity and practicallity.

He will look at the interlock and ask to see the UL listing on it to ensure it is listed for this purpose. No UL listing, no approval. Plain, simple, consistant. Not a lot of creativity there, but a good measure of practicality.

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.

How are these two subject related or was no answer required?

this is one of those moments, it's best to go with the industry standard. Don't try to make a complicated, and irregular set up of your own.

Incidentally, the disconnects appear to be single pole.

According to Solar Flaire :

If you're backfeeding, you have a lethal boobytrap lying in the dirt.

Worse if it's upstream of the last polepig.

I think it's pretty obvious how these subjects are related. You asked who was going to live there after hte OP has installed his key interlock system. From that, one would infer that you were questioning what would happen if a new owner took possession, who may not keep a key in a safe, or even know or care about the correct procedure to keep the generator from backfeeding the utility. But previously you had stated that only a retarded lineman could have a safety issue with a generator backfeeding the utility lines, that it was no big deal. That lead to my question, as to why you would then care about who takes over the house after the OP.

Code says you must have break before make and no way of ever allowing both to be connected at the same time. Those do not appear to provide that. Basically, you need a large dptt switch, which is what the transfer switches create for you. Besides, with that sort of thing, you have no easy control of which ckts are drawing power; you can't insure that some are off and some are on. Unless you have a HUGE generator, that could end up being a pretty big problem and hard on the generator to boot. You'll need a transfer switch to meet fire and building codes, plus a quick disconnect outside (here in NY at least) for emergency services to use. This is also definitely an insurance issue; not something they'd miss or overlook should a disaster occur.

Pop`

HTH Pop`

Um, yes, they do if they are mounted properly and one key is used.

That's what the breaker panel is for.

i

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.

Maybe the colour should be a factor too. I don't know why you make such silly statements when the text is black.

Kirk keyed interlocks are not an open point for human safety. Make before break interlocks can be.

When you have a statement from any credible source that agrees with your position that backfeeding a utility line with a generator is only a safety hazard if the lineman is retarded, please post it. Why don't you start with contacting your local electric company and see what they have to say. Don;t you think it just a little bit strange, that in this whole thread, you're the only one with that position? Or perhaps you're not aware that linemen have been killed by this. Or maybe, by your expertise, they were retarded.

In my experience, working in field camps having main and backup generators and a either, but not both, switching system is to use, depending on number of phases a three or four pole double throw switch, or three or four pole breakers. When using the breakers they are mounted one above the other and one is inverted. then a handler is attached to the breaker handles. Push the handle up and one breaker turns on, the other off. Pull it down and you have the opposit configuration.

If you want the added safety of a separate disconnect then add a normal commercial disconnect between the switching system and the load.

Bruce in Bangkok (brucepaigeatgmaildotcom)

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