Interlock locks to be used in lieu of transfer switch

[Nomen Nescio]

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

[Chris Lewis]

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]

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?

[Pat]

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.

[Solar Flaire]

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.

[Solar Flaire]

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

[Stormin Mormon]

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.

[Chris Lewis]

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.

[trader4]

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.

[Solar Flaire]

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.

[Solar Flaire]

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

[trader4]

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.

[Chris Lewis]

According to Solar Flaire :

_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.

[Mark Rand]

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

[Chris Lewis]

According to Mark Rand :

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.

[George]

No point missed. He isn't engineering anything. He is trying to cobble stuff together to avoid the use of a proven, approved for the purpose and readily available DPDT transfer switch.

You design, test and submit for approval alternative devices when a suitable device is not manufactured.

[Mark Rand]

It's not a switch, it's an interlock. To be interfaced with the switch to prevent it closing unless the interlock bar is retracted. It thus becomes physically impossible to have both switches closed at once, since the switch must be opened in order to be able to extract the key and the key must be in the interlock in order to close the switch. Since there is only one key available, only one switch can be closed at a time... even if they are a mile apart.

Iggy's solution is far safer than the silly panels with switches linked together. Specifically, it is fail safe.

Mark Rand RTFM

[Mark Rand]

A double pole double throw switch is _not_ a safe design for a transfer switch an inductive load that causes arcing on the opening contacts can result in connecting both sources together or one source onto a fault. A panel that has pairs of switches tied together can connect both sources to the load if one switch or the link fails, with no opportunity to verify that the disconnect occurred before the connect occurred. Neither protect against trying to synchronise the source network a long way out of phase with the load network

Iggy's solution requires that one source is isolated well before the other source can be connected.

Oh, and I have, in my role as an electrical engineer, in the last year had to refuse to connect UL and CE marked equipment supplied by a major (Blue) manufacturer because it was unsafe as assembled. When the installation "engineer" claimed that similar equipment had been installed all over the country, I had to state that it's use would be illegal in each of those installations. I'm not that bothered about safety except where the lack of it endangers people, then I get quite particular.

regards Mark Rand RTFM

[Anthony Matonak]

It's only safe as long as someone follows the rules and there is only one key. You could just as easily leave out the key and just keep the rule, "Thou shalt switch OFF the one before you switch ON the other", which is nothing at all like a proper transfer switch.

Anthony

[Ignoramus3938]

I will put the second key in the bank safe deposit box. Or even throw it away.

i