Interlock locks to be used in lieu of transfer switch

Page 3 of 9  


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
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mark Rand wrote:

Really? I think there are at least a few in everyday use...
A panel that has

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm coming in late on this, didn't see the original post but from reading the replies I'm infering Iggy wants to use a couple of keyed lock mechanical doohickies to prevent his genny breaker & mains disconnect from both being "on" at the same time.
This is, everyplace I've ever been, perfectly legal as long as theres only one key & it can only be withdrawn from the lock when the doohicky has the breaker in the "off" position. I've had a number of systems like this in sites where the feeds were physically seperated.
Now, that isn't to say I don't prefer a single changeover switch type of deal, 'cause I very much do, but the keyed switchs are perfectly acceptable if properly designed.
This has been discussed before somewheres on usenet, I remember posting on it.
H.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 13 May 2007 14:43:04 GMT, Howard Eisenhauer

Yes, a "Kirk Key®" interlock is legal - but ONLY where access is restricted to trained and responsible personnel like at power plants and industrial buildings. People who know what will happen if they screw up, and that they'll be held fully to account for it.
It is too easy to deliberately bypass that type of mechanical interlock and cause a backfeed, as easy as unbolting the front panel of the switchboard that the interlocks are secured to and operating the circuit breakers out of sequence. Takes only seconds.
And there are too many fools who are ready and willing to do it out of total and deliberate ignorance of the consequences.
For residential and light commercial/industrial applications where the transfer equipment is not secured and can and will be operated by untrained personnel, it HAS TO BE type accepted for that use. That calls for a pre-packaged automatic or manual transfer switch of some sort that has failsafes against backfeeds, and eliminates any "Kirk Key®" type systems from consideration.
Unless you want to be up for multiple counts of Murder 2 for backfeeding the utility service and killing a few workers on the line gang, out trying to restore power after the storm...
--<< Bruce >>--
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK, you just went over the top.
Vaughn
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 13 May 2007 18:52:33 GMT, "Vaughn Simon"

Not at all - a person properly trained in electricity theories, construction codes and the like would know the risks involved, and if he did cause a backfeed into the utility system anyway and someone dies, Murder 2 (done deliberately but with no premeditation) would be a reasonable charge to level.
Though I'd bet most career prosecutors would charge it as Murder 2 just so they could plea-bargain it down to an easy Manslaughter.
IANAL, but even 120VAC is a potentially lethal voltage. And when it kicks backward through a transformer and is suddenly boosted to 5KV to 35KV or more, then it's really easy to "reach out and touch someone."
And I have personal knowledge of how massive screw-ups of this magnitude can and do happen, but please DAMHIKT. Let's just say it wasn't pretty, and leave it at that.
--<< Bruce >>--
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am both an electronics technician and a licensed electrician, so I think I have had a bit of training in electricity theories.

That is absolute bullshit.
Don't get me wrong, I believe in doing things right. In fact, I have a proper transfer switch on my own home. But why must this transfer switch conversation always disintegrate into such childish nonsense?
Vaughn
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Nope. It's called, 'reckless disregard for others resulting in the death of someone'. In many states that fits the statute of murder. In NY it's not called Murder-2 since that is 'premeditated' while Murder-1 is 'causing the death of a law enforcement person while committing a felony act'. In NY it would be manslaughter in the first-degree.
All it would take is an accident and the DA being able to prove that you 1) had the prerequisite knowledge yet 2) choose to deliberately ignore the code requirements and that 3) your actions resulted in the death.
daestrom
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Let's be careful making legal judgments.
Making a mistake while trying to do a good job is not reckless.
"Reckless" in this context would be, for example, deliberately connecting the generator to utility side as an experiment.
i
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's true. But the other poster is talking about blatently ignoring the code requirements and claims to be an electrical engineering type.
So, in his situation, he is dancing on the edge of 'reckless disregard for human life'. He knows the risks, he knows it's against the code, he knows it could put someone else in jeopardy, yet he's talking about willfully doing it anyway. He may 'get away with it' several times and even be lulled into a false sense of safety. But if there is an accident, he can't claim, "I didn't know any better."
Now, if he was just some amateur Joe, with a 'suicide cord' and didn't know any better, then that would not necessarily be 'reckless disregard'. But that ain't what the other poster said.
daestrom

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Are you a lawyer in real life or do you just play one on the Internet? If the former, can you provide us a link to a comparable case?
Frankly, I am tired of the silliness that always results from these transfer switch threads.
Vaughn
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 15 May 2007 21:16:55 GMT, "Vaughn Simon"

Although I would never advise someone to use a generator without a listed transfer device (and that can be a breaker interlock if it was tested on that panel by a NRTL) but I agree, these threads get silly. Your puny little generator will not handle "the grid" for more than a few miliseconds. When it hits the locked rotor of your neighbor's AC units it will trip out. Linemen are not going to die since they have procedures that assume NOTHING is dead until they prove it and then they short it out. I suppose if you did have a very localized failure you might light up a neighbor but the power company is likely to do that too when they restore power.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 15 May 2007 22:43:36 -0400, snipped-for-privacy@aol.com wrote:

I'd rather see some silliness, as long as the subject is fresh in your mind when you go to hook up a generator - it's always the preferred attitude over death-ness.

The trick is where the primary line feeding your transformer goes physically open, so you aren't trying to backfeed "the rest of the grid" you are only energizing your own service transformer. If you are the only house on that line there are no foreign loads to drag down and stall your generator, but you're still boosting that 120V and sending 5KV to 35KV back down that string of poles.
(Gee, why is our streetlight out at the highway back on?)
If the line crew is out fixing the downed circuits, they know that the line is off from the feed end, they've already done the Lockout/Tagout and ground bond cable safety procedures. It's dead, they made sure of it.
But if they are too far away from your homestead to hear your little generator chugging away, and they don't use the same level of caution in checking, ground bonding and handling the supposedly dead load-side power line that you are backfeeding...
"Don't worry about that line Charlie, it's dead..."
--<< Bruce >>--
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bullshit. When you get proper training in line maitenance techniques you will agree the whole argument that reappears every two months for the last ten years is bullshit.
and why? All because some amateur thinks he can beat the law and save a few bucks and wants somebody here to back his scheme up so he can feel smarter than the rules.
message wrote:

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 16 May 2007 19:14:29 -0500, "Solar Flaire"

Do me a favor, please. Drop the belligerence when I'm On Your Side.
I don't want the amateur to cockamamie the connections and create a potential backfeed in the first place. The OP of this thread (Igor) is a r.c.metalworking regular and will get "great ideas" like using a set of Kirk Key interlocks he got for real cheap (or free) on a home install, but will also abandon the idea when you prove your point as to where the flaws are with them.
(I think that he already conceded on the idea a while back, but the bickering^h^h^h^h^h^h^h^h^h discussion plays on...)
And I am aware of the precautions that the linemen need to make. I normally don't touch anything over 480V, but I've seen the switch tag-outs and the safety ground-out jumpers on the 34.5KV lines in the area when they're adding a new service. We had a vehicle shear off the pole that dropped our neighborhood at 2 AM, and took out three 5KV feeders. I stood there watching them do all the substation lockouts over the radio, and getting clearance to work.
But whenever you develop safety equipment or work procedures that are meant to be "Idiot Proof", Mother Nature rises to the challenge and develops a craftier idiot. There are ways to screw up Just Right and create a backfeed that doesn't stall the generator set or trip out the protection...
And there are always linemen that don't follow every rule in the book to the letter every single time, be it through fatigue (working a week of 20-hour days during an ice storm or other disaster will do that...), inattention, lack of ground-out cables on hand, or just plain apathy since "That never happens."
And that's when the million-to-one potential exists for somebody to touch a "dead" line and ground at the same time and get nailed.
--<< Bruce >>--
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Or they might walk across the street, overtired and the boom will fall on the neighbour's nailgun and fire a framing nail through the lineman's heart and kill him too.
I have to agree with you, whatever it was now...LOL.. The best one was everybody is sick of the "is it OK to bypass safety if I do it this way ot that way?" question. Have a good one!
message

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

And yet, linemen do get electrocuted while working on lines. One can sit smugly back and say, "It's because they didn't follow procedures." But they are still dead.
In http://www.powerlineman.com/lforum/showthread.php?tq1&highlight=home+generator there is story that a back feed killed someone in Flomonton AL. They specifically mention backfeeding from a home generator. http://www.brewtonstandard.com/articles/2005/07/18/news/news02.txt http://blog.constructionlawblog.net/archives/004368.html (sixth paragraph)
FEMA seems to think there is a risk to 'unwary utility lineman' http://www.fema.gov/news/newsrelease.fema?id 018
Cayman Islands Health Service Authority seems to think wiring a generator improperly is a risk. http://www.gov.ky/pls/portal/docs/PAGE/CIGHOME/PRESSROOM/ARCHIVE/200410/GENSAFETY.PDF
Team Florida seems to think you could be, "... responsible for the electrocution of a lineman." http://www.myflorida.com/dms/tf2k/citizens_gas_oil.html
So, is one life enough to stop calling it 'bullshit', or do should we google for some more?
Just about every utility in the country will tell you that an improperly connected generator can be an electrocution risk for their linemen. Yet some arm-chair wannabe's still think it's 'bullshit' because they took a Saturday afternoon course on wiring at a big box store and bought a book.
I don't know which is worse, the one's that don't know any better and are just trying to avoid paying a professional, or the 'experts' that 'know better' and 'would never leave the mains breaker shut'. They know there's a risk, but talk themselves into believing, "It could never happen. I won't make that mistake. Besides, linemen are supposed to be properly trained." Tell it to the widows and children...
Do a web search, ask your utility, go to a professional lineman's forum and ask them what they think of the idea. Ask *them* if the whole idea of a backfeeding generator killing someone is 'Bullshit'.
daestrom
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have, and it is bullshit, to use trained linemen as an excuse.
You profess to have so much vast knowledge of electrical systems and utilities. Ask them yourself.
Utilty workers have the lowest compensation rates of any profession. there is a reason for that. Oh yeah, I forgot the US is about 30 years behind in safety measures according to the trainers training in most states. This may not apply there.

http://www.powerlineman.com/lforum/showthread.php?tq1&highlight=home+generator

http://www.gov.ky/pls/portal/docs/PAGE/CIGHOME/PRESSROOM/ARCHIVE/200410/GENSAFETY.PDF
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It would seem to me that if your power is off you actually are not connected to "the grid". How much of the distribution sysetm is dead but still connected to your house is often an unknown variable. All of the pros and cons of every conceivable type of situation have been mentioned many times. There are no new arguments for either position.
I think it is just a matter of whether you want to do the correct, legal, and safest thing or not. Some people even stop at stop signs when no other cars are present. Others do not. Neither group is likely to change its habits.
Don Young
wrote:

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have to agree with you on that one!
It all starts with "if the lineman has complete disregard of....." "Then the child reaches out and touches the 115kV lne that was backfed from the home generator"
Our HV lines, especially the 500kV lines are always within easy reach so we can connect our appliances.
Fuck! people. It is illegal and stupid to shortcut the safety stuff.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.