Our 50amp transfer unit only switches power from grid to generator after
30 seconds from when it sees power from the gen.

http://www.green-trust.org/wiki/inde...ransfer_Switch

Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

Ignoramus25850 wrote:
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i

I don't claim to have really followed it, but do know that the contacts on
my TS relay fused closed. Unless your device accomodates that (on the line
contacts) safely, it is no good.

"Ignoramus25850" wrote in message
...
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

Where I live the utilities require physcial and electrical interlocks.
Most residential panels do not lend themselves to a physcial interlock.
Square D is the only one that I know of that has a physical interlock
between the main and another breaker.
Then comes to the issue of the equipment being service rated. Then comes UL
listings.
A contactor/motor starter off the shelf I do not believe is service rated.


There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i

Check with your local authorities and utility before embarking on the
project.
If you can build this in 30 minutes, your a lot better than I am.

"SQLit" wrote in message
...

"Ignoramus25850" wrote in message
...
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

Where I live the utilities require physcial and electrical interlocks.
Most residential panels do not lend themselves to a physcial interlock.
Square D is the only one that I know of that has a physical interlock
between the main and another breaker.
Then comes to the issue of the equipment being service rated. Then comes
UL
listings.
A contactor/motor starter off the shelf I do not believe is service rated.


There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

One piece of advice. I am not seeing it in your description, but I might be
missing it. Do you have a plan for seeing that the incoming power from the
street is back on?

I only mention this as I once had a friend do something similar, and failed
that part. Worse yet, he had to get into his car to drive by a few
neighbors to see if power had been restored. Even worse yet he had to drive
by two of them as they had generators. Remote area it was.

--
Chris

If you can read this, thank a teacher. If it is in English, thank a
soldier. If it is in ebonics, thank your Congressman.

On Tue, 06 Sep 2005 15:21:20 GMT, Ignoramus25850
wrote:

I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i
Sounds like a good idea - BUT. Can you ensure the generator contactor
can NOT stay closed when the switch is shut off to turn the main
disconnect on? You need a failsafe system that makes it IMPOSSIBLE for
the generator to "lock on" - whether by killing the generator before
being able to reconnect to mains or whatever. That is why virtually
all transfer switches employ what boils down to a mechanical DPDT
knife switch.

Since you are going for a manual changeover, you might want to consider one
of these simple kits: http://www.interlockkit.com/intro.html



"Ignoramus25850" wrote in message
...
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i

On Tue, 06 Sep 2005 15:42:47 GMT, Ignoramus25850
wrote:

On Tue, 06 Sep 2005 15:30:19 GMT, Toller wrote:
I don't claim to have really followed it, but do know that the contacts on
my TS relay fused closed. Unless your device accomodates that (on the line
contacts) safely, it is no good.

What is a TS relay?

I want to use a large contactor, rated for way more than what my
generator can supply. My genset generates about 28A, whereas the
contactor that I would use is rated for 30A.


You want AT LEAST a 50 amp rated contactor, at 500 volts, for a safety
factor. 30 amps is cutting it a bit fine, since you do not have zero
crossing switching.




i

On Tue, 6 Sep 2005 11:47:41 -0400, "Chris" wrote:


"SQLit" wrote in message
...

"Ignoramus25850" wrote in message
...
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

Where I live the utilities require physcial and electrical interlocks.
Most residential panels do not lend themselves to a physcial interlock.
Square D is the only one that I know of that has a physical interlock
between the main and another breaker.
Then comes to the issue of the equipment being service rated. Then comes
UL
listings.
A contactor/motor starter off the shelf I do not believe is service rated.


There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

One piece of advice. I am not seeing it in your description, but I might be
missing it. Do you have a plan for seeing that the incoming power from the
street is back on?

I only mention this as I once had a friend do something similar, and failed
that part. Worse yet, he had to get into his car to drive by a few
neighbors to see if power had been restored. Even worse yet he had to drive
by two of them as they had generators. Remote area it was.
On my brothers recreational property the meter is at the road (with a
disconnect and main breaker) and there is a red pilot lite on the back
of the service box that tells him power is on. His transfer switch is
back at the buildings. When the light is on, he knows the grid is up.

Crossposts deleted

I'm all for building stuff that does what you want it to. But when you
start talking 7 kw of power plus the potential to have life endangering
consequences I start to drag out my "safety first" speech.

Officious speech mode on
There must be a POSITIVE interlock to avoid backfeeding to the grid.
This interlock should satisfy BOTH the power company and the electrical
inspector. Period. No discussion. Positive in this case means you, your
neighbor, an electican, or your power company guy can all work it
correctly without fear of screwing up. It should also be physically
positive in the sense that it won't bend short of using a vice grip or
prybar. Your description says something about some vague "mechanical
device" to accomplish this. I don't buy it.
Officious speech mode off

Other than that, why are you going though all the hassle of relays, 9
volt batteries, etc when all you need to do is switch a couple of circuits?

I also think you will have some issues with trying to power the whole
house with the 7 kw generator. I see a few neighbors trying to run their
houses with 5 kw (granted these are a bit smaller), modern houses take a
LOT of power, if several things come on at once, you kill the generator.
But with proper power management, you should have enough power to run
a small window AC unit as well as the rest of the required items like
refrigerator, freezer, well, and a few lights.

Most folks just use the 60 amp (??) Square D transfer switch to have 4
circuits that can be cut over to the generator. $100 or so, UL listed,
NEC compliant, looks like a sub panel, takes an afternoon to install.
The even simpler route is to have the critical items (eg furnace)on
plugs, just move the plug from grid to generator as required.

Cheers.

Ignoramus25850 wrote:
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i

"Ignoramus25850" wrote in message
...
On Tue, 6 Sep 2005 11:47:41 -0400, Chris wrote:

"SQLit" wrote in message
...

"Ignoramus25850" wrote in message
...
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

Where I live the utilities require physcial and electrical interlocks.
Most residential panels do not lend themselves to a physcial interlock.
Square D is the only one that I know of that has a physical interlock
between the main and another breaker.
Then comes to the issue of the equipment being service rated. Then comes
UL
listings.
A contactor/motor starter off the shelf I do not believe is service
rated.


There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

One piece of advice. I am not seeing it in your description, but I might
be
missing it. Do you have a plan for seeing that the incoming power from
the
street is back on?

I only mention this as I once had a friend do something similar, and
failed
that part. Worse yet, he had to get into his car to drive by a few
neighbors to see if power had been restored. Even worse yet he had to
drive
by two of them as they had generators. Remote area it was.


Chris, you raised a great question. As of now, I do not have any
provisions for seeing incoming power. I see it as a fully separate
issue from what I am asking, but it is a very good one.

My concern with doing anything to see incoming power, when the mains
breaker is off, is that I would connect an electrical load (a light
bulb perhaps) before the main breaker. That seems a little bit scary.

I could, however, install a little button style light or some such.



Ok just wanted to make sure you had it in mind. I know how we can get.
Focus on one thing and forget the obvious.

--
Chris

If you can read this, thank a teacher. If it is in English, thank a
soldier. If it is in ebonics, thank your Congressman.

Ignoramus25850 wrote:

On Tue, 06 Sep 2005 11:24:10 -0400, Steve Spence wrote:
Our 50amp transfer unit only switches power from grid to generator after
30 seconds from when it sees power from the gen.

http://www.green-trust.org/wiki/inde...ransfer_Switch

What I am describing is a manual switch. ...

Yes. And?

You will definitely need to check w/ your local utility. They may have
requirements that any transfer switch you put in place be a listed
device.

I'm happy with my automatic switch.

Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

Ignoramus25850 wrote:
On Tue, 06 Sep 2005 11:24:10 -0400, Steve Spence wrote:

Our 50amp transfer unit only switches power from grid to generator after
30 seconds from when it sees power from the gen.

http://www.green-trust.org/wiki/inde...ransfer_Switch


What I am describing is a manual switch. The user would have to
perform the following steps manually:

1) Turn off the main breaker.
2) Turn on the mechanical switch for DC input circuit to the relay,
which becomes possible only if the main breaker is off.
3) Turn on the generator (could be done at any other time in this
sequence)
4) Press the START button on the start/stop switch.

At any time, if the interlocked mechanical switch is turned off, the
contactor would open and electrical power would no longer be supplied
to the house from the generator. The interlocked switch must be in the
off position for the main breaker to be turned on.

i


Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

Ignoramus25850 wrote:

I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i

"Ignoramus25850" wrote in message
...
On Tue, 06 Sep 2005 11:24:10 -0400, Steve Spence
wrote:
Our 50amp transfer unit only switches power from grid to generator after
30 seconds from when it sees power from the gen.


http://www.green-trust.org/wiki/inde...ransfer_Switch

What I am describing is a manual switch. The user would have to
perform the following steps manually:

1) Turn off the main breaker.
2) Turn on the mechanical switch for DC input circuit to the relay,
which becomes possible only if the main breaker is off.
3) Turn on the generator (could be done at any other time in this
sequence)
4) Press the START button on the start/stop switch.

At any time, if the interlocked mechanical switch is turned off, the
contactor would open and electrical power would no longer be supplied
to the house from the generator. The interlocked switch must be in the
off position for the main breaker to be turned on.

I caught your concept of a "manual transfer device".

Where I live there MUST be mechanical interlocks. That means if either
breaker is forced into the other position BOTH breakers change state at the
same time. I am talking about internal switching from one device to
another. Steps 1&2 would have to happen with one operation.

The utilities used to have a requirement for "visible blade disconnection" I
got into a situation where no one made a 4000 amp visible blade disconnect.
So they changed the spec to mechanical interlock.
I will bet that your contactors are not 'service rated'. Do you know the
fault current your generator is capable of? How about the serving utility?
10000 amps is pretty common I have seen places where special circuit
breakers were needed because the fault current was over 10k.

Call the local jurisdictional authorities and talk to them. I do not know of
a utility that would allow what you describe. I am familiar with the
utilities in 4 western states.



--------snipped----------------

"Ignoramus25850" wrote in message
...
On Tue, 06 Sep 2005 16:31:40 GMT, Ignoramus25850
wrote:
On Tue, 6 Sep 2005 12:05:57 -0400, John Grabowski
wrote:
Since you are going for a manual changeover, you might want to consider
one
of these simple kits: http://www.interlockkit.com/intro.html

Yes, another good choice. Thanks John.

As of now, my favorite plan is as follows.

1. Install a premade interlock kit rather than dick around with
relays. Mostly for legal reasons.

2. Also have a mag starter style switch in the line from generator to
the power panel, to help prevent arcing in the circuit breaker that is
used to feed the panel.

i

I'm not sure what your concern for arcing in the circuit breaker is about.
Circuit breakers are made to be turned on and off under load. You could
always install wiring and a circuit breaker bigger than the rated capacity
of your generator.

John G.

"Ignoramus25850" wrote in message
...
On Tue, 06 Sep 2005 15:30:19 GMT, Toller wrote:
I don't claim to have really followed it, but do know that the contacts
on
my TS relay fused closed. Unless your device accomodates that (on the
line
contacts) safely, it is no good.

What is a TS relay?

I want to use a large contactor, rated for way more than what my
generator can supply. My genset generates about 28A, whereas the
contactor that I would use is rated for 30A.

i


Not a good idea at all!!
A transfer switch has to be designed so if it fails it absolutely can not
back feed into the utility power. If your contactor fails closed, and
believe me it does happen, your generator can back feed per to the utility.

I install and service standby generators, if one of our transfer switches
fail there is absolutely no way it will back feed power. The transfer switch
may fail in either position, but no way will it cause a back feed!
Greg

"Ignoramus25850" wrote in message
news
On Tue, 06 Sep 2005 12:04:31 -0400,
wrote:
On Tue, 06 Sep 2005 15:21:20 GMT, Ignoramus25850
wrote:

I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

It would work something like this. There will be a mechanical device
and a switch such that the switch could be closed only when the main
breaker is off. When the main breaker is on, the switch could not be
closed.

There will be a DC circuit, powered by a 9V battery, that would be a
signal input to a solid state crydom relay. The power contacts of the
relay would be in series with the power from generator. When the relay
is closed (only when the mains breaker is open), and a START button is
pressed on the start/stop switch (like ones used for mag starters),
the main contactor would close. The STOP button interrupts input to
the contactor, causing it to open. Turning the little switch near the
main breaker off would also interrupt the circuit, opening the
contactor.

This seems to be a very fool proof system. I can build it in 30
minutes, except that I would need more time to fabricate a mechanical
switch opener/closer.

I would like to ask that those who can visualize what I am describing,
to comment on this plan. Thanks

i
Sounds like a good idea - BUT. Can you ensure the generator contactor
can NOT stay closed when the switch is shut off to turn the main
disconnect on? You need a failsafe system that makes it IMPOSSIBLE for
the generator to "lock on" - whether by killing the generator before
being able to reconnect to mains or whatever. That is why virtually
all transfer switches employ what boils down to a mechanical DPDT
knife switch.


I am open to suggestions here. I would think that that's what
contactors are made for, to open and close reliably, when operated at
or below the rated power. Otherwise they would be very unsafe for all
kinds of machines that they control.

i


Contactors can and will fail closed! Not a good idea for a transfer switch!
I could not count the number of failed closed contactors I have replaced in
the last six years!!
Greg

"Ignoramus25850" wrote in message
...
I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

Not a DIY job. Get a UL listed transfer switch, have a licensed electrician
install it and get it inspected.

On Tue, 6 Sep 2005 17:54:59 -0500, "Greg O"
wrote:



Contactors can and will fail closed! Not a good idea for a transfer switch!
I could not count the number of failed closed contactors I have replaced in
the last six years!!
Greg

I suppose you COULD use a DPDT contactor - but then why not just use
the old standby knife switch. The contactor needs power to activate
it.

And if the contactor sticks in the line position you can't use the
genset. If it sticks in the genset position, you cannot connect to the
grid. - so you are back to manually operating it anyway. Back to the
knife switch.

riggghhttt. anyone with a bit of sense can install a transfer switch.

Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

ATP* wrote:

Not a DIY job. Get a UL listed transfer switch, have a licensed electrician
install it and get it inspected.

On Tue, 06 Sep 2005 15:21:20 GMT, Ignoramus25850
wrote:

I have been playing with using relays of various kinds, as well as
contactors. I already built 2 phase converters, and a remote switch,
for instance. I have a few 90A and 75A contactors and solid state
relays and mag starter buttons and whatnot.

Here's what I have been thinking about. I have a 7 kW Onan DJE
generator that I have for emergencies. I want it to power my entire
house in emergencies (I know that I cannot run AC and some other
devices while under generator power).

It is expensive and painful to install a transfer switch. I want to
make something easier and cheaper to power the house in case of
emergencies, while at the same time preventing backfeeding.

I can, instead of a transfer switch, build a system that includes a
contactor, a mag starter, and a relay that only closes the main
generator contactor when the main circuit breaker is in the OFF
position.

Go get yourself a UL Listed transfer switch of some sort. The
cheapest way is a Double-Throw safety switch. Looks just like the
fused disconnect for a motor, but the lever goes On-Off-On.

Or do some heavy-duty scrounging and buy a new or good used
automatic transfer switch that you can install. DO NOT TRY TO INVENT
THIS YOURSELF. It is life-safety critical, and there is absolutely no
reason for you to reinvent the wheel. Better you should pay a bit for
the right equipment - Use a proven design.

If your homebrewed transfer switch design is flawed, creates a
backfeed and kills a lineman or two working on power restoration (or
even just surprises the hell out of them when they find out the line
is energized) I can guarantee that they will find you, and that the
proceedings will not be pleasant.

If you do anything permanent, get it checked out and passed by the
local building inspector, and by the local utility. This is critical.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

"Steve Spence" wrote in message
...
riggghhttt. anyone with a bit of sense can install a transfer switch.

Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

I've seen plenty of simpler electrical jobs screwed up or just poorly
executed by people with more than a bit of sense. In any case, it has to be
listed and inspected per the local utility regulations.

ATP* wrote:

Not a DIY job. Get a UL listed transfer switch, have a licensed
electrician install it and get it inspected.

maybe in your community, but not in mine. I wired my whole house, panels
and entrance. The power company only dropped to the meter on the pole.
that was the end of it. I did the rest.

Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

ATP* wrote:


I've seen plenty of simpler electrical jobs screwed up or just poorly
executed by people with more than a bit of sense. In any case, it has to be
listed and inspected per the local utility regulations.


ATP* wrote:


Not a DIY job. Get a UL listed transfer switch, have a licensed
electrician install it and get it inspected.

On Wed, 07 Sep 2005 18:51:51 -0400, Steve Spence
wrote:

maybe in your community, but not in mine. I wired my whole house, panels
and entrance. The power company only dropped to the meter on the pole.
that was the end of it. I did the rest.

Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html

ATP* wrote:


I've seen plenty of simpler electrical jobs screwed up or just poorly
executed by people with more than a bit of sense. In any case, it has to be
listed and inspected per the local utility regulations.


ATP* wrote:


Not a DIY job. Get a UL listed transfer switch, have a licensed
electrician install it and get it inspected.



In Washington state you are allowed to wire your own house. It then
must pass inspection. After that you must live in it for five years
before you can sell it. This is done to prevent bad wiring done by
people who are building spec homes. Not that everybody who builds a
spec home is going to do a bad job. Just that some people will skimp
and not use qualified people to do the wiring.
ERS

"Eric R Snow" wrote in message
...
On Wed, 07 Sep 2005 18:51:51 -0400, Steve Spence
wrote:
In Washington state you are allowed to wire your own house. It then
must pass inspection. After that you must live in it for five years
before you can sell it.

Strange! Here a homeowner can pull a permit to do most anything. Then the
job must pass inspection just like anything else and you are done with the
process.

Vaughn

Eric R Snow wrote:
Not a DIY job. Get a UL listed transfer switch, have a licensed
electrician install it and get it inspected.



In Washington state you are allowed to wire your own house. It then
must pass inspection. After that you must live in it for five years
before you can sell it.

That seems like a pretty harsh regulation. Here I believe you can
legally wire your own house, but you're supposed to have it inspected
afterwards, and certainly before you sell it. But we also have a stupid
new law which means that only qualified electricians can buy consumer
units. Most people with time and good practical skills, but little
money, aren't going to pay an electrician to wire their workshop.
They'll find a consumer unit from a friend, or a demolition site, or a
dumpster. It just drives work underground. Another sad example of
European over-regulation!

Chris

Excellent suggestion.

Ig, you come across as an enterprising and resourceful individual. I
would suggest focusing your talents on something that is not so
dangerous to...

- your finances
- your power company employees

If this homebrew setup would fail with fatal results for someone, you
will be on the hook litigation wise. There are reasons why sometimes we
spend the money on UL listed products, have a licensed electrician do
the work and have inspections....all to cover us legally.It only takes
one fatal failure to wipe you and your family out financially.

Let know how you end up doing it.

TMT

On Wed, 07 Sep 2005 18:51:51 -0400, Steve Spence
wrote:
ATP* wrote:

I've seen plenty of simpler electrical jobs screwed up or just poorly
executed by people with more than a bit of sense. In any case, it has to be
listed and inspected per the local utility regulations.

Some of the most screwed up DIY installations I've ever had to
rework were done by engineers and (literally) 'Rocket Scientists' who
thought they knew better. I think half the parts the former owner
used for the additions at this house (before we bought it) "fell off
the loading dock" at Rocketdyne in the '60's, though I can't prove it.

maybe in your community, but not in mine. I wired my whole house, panels
and entrance. The power company only dropped to the meter on the pole.
that was the end of it. I did the rest.

In EVERY community I know of, the electrical utility won't tie onto
a power panel and provide a meter unless the panel has been inspected
and approved as safe by /somebody/ referred to as the Authority Having
Jurisdiction or AHJ.

If there isn't a city building inspector, the job falls back to the
county or parish level. If it's on state or federally owned property,
then their inspector has the authority. The power utility doesn't
want the legal liability if someone gets hurt or killed, so they
insist on it.

Now after the AHJ has passed the installation, the utility has
connected the feed, and both parties are long gone, /then/ you can do
additional work without a permit, and cheat as much as you want, with
one gigantic caveat: As long as they never see it.

And if the AHJ comes back to check something else and sees you have
cheated, now you have a problem. They can (and will) force you to fix
it. If you don't, their ultimate recourse is to call the utility and
tell them to cut the feed and pull the meter, the installation is no
longer safe. Darkness and quiet quickly ensues. (*)

(* At least on things run from utility power, noting the crosspost.)

Except for mobile homes / manufactured housing in California, where
inspection of the meter pedestal and outside wiring is a city or
county responsibility like normal, but anything electrical inside or
on the coach itself is inspected by a State bureaucrat. Our local
mobile home inspector drives into Western LA County from Riverside,
where the closest office is.

-- Bruce --
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

In article ,
Ignoramus11916 wrote:
On Thu, 8 Sep 2005 00:37:16 +0000 (UTC), Christopher Tidy
wrote:
Eric R Snow wrote:
Not a DIY job. Get a UL listed transfer switch, have a licensed
electrician install it and get it inspected.



In Washington state you are allowed to wire your own house. It then
must pass inspection. After that you must live in it for five years
before you can sell it.

That seems like a pretty harsh regulation. Here I believe you can
legally wire your own house, but you're supposed to have it inspected
afterwards, and certainly before you sell it. But we also have a stupid
new law which means that only qualified electricians can buy consumer
units. Most people with time and good practical skills, but little
money, aren't going to pay an electrician to wire their workshop.
They'll find a consumer unit from a friend, or a demolition site, or a
dumpster. It just drives work underground. Another sad example of
European over-regulation!

Christopher, what do you mean by a consumer unit?


Lets see how my grasp of european terms is..


consumer unit = Breaker panel (made of plastic, with DIN rails)

RCD = GFI (or something very similar)

T+E = Twin+Earth = Romex

ring main = circuit fed from both ends (from the same breaker)





--
-- Welcome My Son, Welcome To The Machine --
Bob Vaughan | techie @ tantivy.net |
| P.O. Box 19792, Stanford, Ca 94309 |
-- I am Me, I am only Me, And no one else is Me, What could be simpler? --

Eric R Snow wrote:
....
In Washington state you are allowed to wire your own house. It then
must pass inspection.

So far, so good...

...After that you must live in it for five years
before you can sell it. ...

How could they possibly enforce that?

On Thu, 08 Sep 2005 08:30:58 -0500, Duane Bozarth
wrote:

Eric R Snow wrote:
...
In Washington state you are allowed to wire your own house. It then
must pass inspection.

So far, so good...

...After that you must live in it for five years
before you can sell it. ...

How could they possibly enforce that?
Beats me. When I wired my shop I learned all sorts of regulations. But
hardly any reasons. In WA the inspection is done by Labor &
Industries. They come out when they come out. And do hold up projects.
My father-in-law is a licensed electrician. I flew him up to WA to
help with the wiring to make sure it all done to code. He told me that
in Santa Clara county in CA the inspectors have 24 hours to show up
and do the inspection. If they don't then the wiring can be covered
and is considered to be up to code. BTW, just because a house is wired
by a "professional" and has passed inspection it doesn't mean that the
wiring will be done correctly. My last house had all the wiring in the
garage and laundry room backwards. So all the white wires were hot and
the black wires neutral. The problem was in a junction box where
someone had connected the wires in reverse. This box had undisturbed
mud and paint on it from the original drywall. So the wiring had not
been changed by any previous owners.
ERS

"Bruce L. Bergman" wrote:

On Wed, 07 Sep 2005 18:51:51 -0400, Steve Spence
wrote:
ATP* wrote:

I've seen plenty of simpler electrical jobs screwed up or just poorly
executed by people with more than a bit of sense. In any case, it has to be
listed and inspected per the local utility regulations.

Some of the most screwed up DIY installations I've ever had to
rework were done by engineers and (literally) 'Rocket Scientists' who
thought they knew better. I think half the parts the former owner
used for the additions at this house (before we bought it) "fell off
the loading dock" at Rocketdyne in the '60's, though I can't prove it.


Local electric utility linemen do some pretty screwed up stuff as well.
The house I'm in now had a utility lineman as an owner previously and
I'm still correcting his mess.

Little things like 240v feeds to the shop wirenutted and left exposed at
ground level, as in individual THHN comes out through hole in brick,
wirenut to more THHN and then disappear underground. The same 240v feed
to the shop is fed from separate 20a and 30a single pole breakers in the
damn panel.

All of the mess to the shop and indeed the crappy stab-lock main panel
are on the agenda to be replaced with a good 200a QO panel for the
house, a 100a QO for the shop, all new wire to the shop in some proper
sch 40 PVC underground to the shop, etc. I figure it's a good weekend
project, not counting pre-trenching in the conduit.

There are plenty of other less significant things that I've been fixing
along the way as well. I do however like the four steel light poles he
used to support the carport roof along side the shop and the two others
with HID lights (mismatched of course) that light the yard.

Pete C.

I hear this all the time. High wire janitors are not electricians or
engineers.

"Pete C." wrote in message
...
"Bruce L. Bergman" wrote:

On Wed, 07 Sep 2005 18:51:51 -0400, Steve Spence
wrote:
ATP* wrote:

I've seen plenty of simpler electrical jobs screwed up or just poorly
executed by people with more than a bit of sense. In any case, it has
to be
listed and inspected per the local utility regulations.

Some of the most screwed up DIY installations I've ever had to
rework were done by engineers and (literally) 'Rocket Scientists' who
thought they knew better. I think half the parts the former owner
used for the additions at this house (before we bought it) "fell off
the loading dock" at Rocketdyne in the '60's, though I can't prove it.


Local electric utility linemen do some pretty screwed up stuff as well.
The house I'm in now had a utility lineman as an owner previously and
I'm still correcting his mess.

Little things like 240v feeds to the shop wirenutted and left exposed at
ground level, as in individual THHN comes out through hole in brick,
wirenut to more THHN and then disappear underground. The same 240v feed
to the shop is fed from separate 20a and 30a single pole breakers in the
damn panel.

All of the mess to the shop and indeed the crappy stab-lock main panel
are on the agenda to be replaced with a good 200a QO panel for the
house, a 100a QO for the shop, all new wire to the shop in some proper
sch 40 PVC underground to the shop, etc. I figure it's a good weekend
project, not counting pre-trenching in the conduit.

There are plenty of other less significant things that I've been fixing
along the way as well. I do however like the four steel light poles he
used to support the carport roof along side the shop and the two others
with HID lights (mismatched of course) that light the yard.

Pete C.