Where to I put a Fuse ??

T

Trudeau

Guest
Im building a little 120 Volt panel (for lack of a better word) to do some
experiments with 120 Volts. In the past Ive just connected up aligator clips
etc and really is unsafe. So Im going to put a switch and outlet on a board
to do it right.

Im not sure exactly where to put the fuse however. To some degree I know it
could go anywhere. But really if something goes wrong I suppose you want the
whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I think is
the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3 for 3
possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the first
time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)
 
Trudeau wrote:
Im building a little 120 Volt panel (for lack of a better word) to do some
experiments with 120 Volts. In the past Ive just connected up aligator clips
etc and really is unsafe. So Im going to put a switch and outlet on a board
to do it right.

Im not sure exactly where to put the fuse however. To some degree I know it
could go anywhere. But really if something goes wrong I suppose you want the
whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I think is
the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3 for 3
possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the first
time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)
Click to expand...
Looks good. However, what's the point of the fuse? Your house should
have a circuit breaker.

If you install a ground fault interrupter plug, that will give you some
added protection should you touch the wrong wire while standing in a
puddle of salt water connected to pipe leading to ground. It won't help
you if you complete a circuit between hot and neutral, but if you keep
one hand behind your back, the worst that will happen is you burn your hand.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
Trudeau wrote:
Im building a little 120 Volt panel (for lack of a better word) to do some
experiments with 120 Volts. In the past Ive just connected up aligator clips
etc and really is unsafe. So Im going to put a switch and outlet on a board
to do it right.

Im not sure exactly where to put the fuse however. To some degree I know it
could go anywhere. But really if something goes wrong I suppose you want the
whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I think is
the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3 for 3
possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the first
time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)



Looks good. However, what's the point of the fuse? Your house should have a circuit breaker.
Click to expand...
The purpose of fuses and circuit breakers is to reduce fire
hazard. By using a low amperage fuse, the OP can use
smaller wire in his project than the 14 AWG wire that
comes from a typical 15A breaker.

If you install a ground fault interrupter plug, that will give you some added protection should you touch the wrong wire while
standing in a puddle of salt water connected to pipe leading to ground. It won't help you if you complete a circuit between hot
and neutral, but if you keep one hand behind your back, the worst that will happen is you burn your hand.
Click to expand...
GFI is a good idea for any workbench where open
equipment will be used. It can save equipment, too.
Melted scope probe ground wires and cables are a
sad sight when probes cost $100 and up.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
"Robert Monsen" <rcsurname@comcast.net> wrote in message news:n_adnec-bdpb7J_fRVn-iw@comcast.com...
 
Robert Monsen (rcsurname@comcast.net) writes:
Trudeau wrote:
Im building a little 120 Volt panel (for lack of a better word) to do some
experiments with 120 Volts. In the past Ive just connected up aligator clips
etc and really is unsafe. So Im going to put a switch and outlet on a board
to do it right.

Im not sure exactly where to put the fuse however. To some degree I know it
could go anywhere. But really if something goes wrong I suppose you want the
whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I think is
the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3 for 3
possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the first
time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)



Looks good. However, what's the point of the fuse? Your house should
have a circuit breaker.

But a fuse specific to this thing means that if you do short out the AC
Click to expand...
line, your lights won't go off, along with any other equipment. Sure,
blowing the circuit breaker in the house is cheaper, but you then have
to go and reset it, and if you had a computer running on the same AC
circuit, you have to restart it.

Michael

If you install a ground fault interrupter plug, that will give you some
added protection should you touch the wrong wire while standing in a
puddle of salt water connected to pipe leading to ground. It won't help
you if you complete a circuit between hot and neutral, but if you keep
one hand behind your back, the worst that will happen is you burn your hand.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
Click to expand...
 
"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:n_adnec-bdpb7J_fRVn-iw@comcast.com...
Trudeau wrote:
Im building a little 120 Volt panel (for lack of a better word) to do
some
experiments with 120 Volts. In the past Ive just connected up aligator
clips
etc and really is unsafe. So Im going to put a switch and outlet on a
board
to do it right.

Im not sure exactly where to put the fuse however. To some degree I know
it
could go anywhere. But really if something goes wrong I suppose you want
the
whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I
think is
the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3 for
3
possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the
first
time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)



Looks good. However, what's the point of the fuse? Your house should
have a circuit breaker.

If you install a ground fault interrupter plug, that will give you some
added protection should you touch the wrong wire while standing in a
puddle of salt water connected to pipe leading to ground. It won't help
you if you complete a circuit between hot and neutral, but if you keep
one hand behind your back, the worst that will happen is you burn your
hand.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
Click to expand...
Thanks for your comments.

I suppose the point of the fuse (I would use one of those little 1Amp Glass
fuses) is to give added protection. Have it blow at a lower level. Nothing I
do is going to draw much power. I suppose I was also thinking that it might
?? save the device that I was connected to from blowing sky high. I know
that 1 Amp in its self can KILL you and Im just trying to be cautious. Why
put in a bigger fuse that you need?
As well there are other things on that circuit. I would like to prevent
everything on that house fuse from being shut down needlessly.

Comments ??
 
FWIW: Have you even given an isolation transformer any consideration, at
least for safety sake? The fuse or GFI is a good idea but isolating your
test bench may be a bit more prudent, IMHO. BTW if you do use an isolation
transformer, do not overload the circuitry or you will just toast it.
"Trudeau" <Trudeau@123.com> wrote in message
news:UK-dnZxZGenM6J_fRVn-qw@rogers.com...
"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:n_adnec-bdpb7J_fRVn-iw@comcast.com...
Trudeau wrote:
Im building a little 120 Volt panel (for lack of a better word) to do
some
experiments with 120 Volts. In the past Ive just connected up aligator
clips
etc and really is unsafe. So Im going to put a switch and outlet on a
board
to do it right.

Im not sure exactly where to put the fuse however. To some degree I
know
it
could go anywhere. But really if something goes wrong I suppose you
want
the
whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I
think is
the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3
for
3
possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the
first
time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)



Looks good. However, what's the point of the fuse? Your house should
have a circuit breaker.

If you install a ground fault interrupter plug, that will give you some
added protection should you touch the wrong wire while standing in a
puddle of salt water connected to pipe leading to ground. It won't help
you if you complete a circuit between hot and neutral, but if you keep
one hand behind your back, the worst that will happen is you burn your
hand.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

Thanks for your comments.

I suppose the point of the fuse (I would use one of those little 1Amp
Glass
fuses) is to give added protection. Have it blow at a lower level. Nothing
I
do is going to draw much power. I suppose I was also thinking that it
might
?? save the device that I was connected to from blowing sky high. I know
that 1 Amp in its self can KILL you and Im just trying to be cautious. Why
put in a bigger fuse that you need?
As well there are other things on that circuit. I would like to prevent
everything on that house fuse from being shut down needlessly.

Comments ??
Click to expand...
 
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=42881&item=3871828713&rd=1&tc=photo

Art wrote:
FWIW: Have you even given an isolation transformer any consideration, at
least for safety sake? The fuse or GFI is a good idea but isolating your
test bench may be a bit more prudent, IMHO. BTW if you do use an isolation
transformer, do not overload the circuitry or you will just toast it.
"Trudeau" <Trudeau@123.com> wrote in message
news:UK-dnZxZGenM6J_fRVn-qw@rogers.com...

"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:n_adnec-bdpb7J_fRVn-iw@comcast.com...

Trudeau wrote:

Im building a little 120 Volt panel (for lack of a better word) to do

some

experiments with 120 Volts. In the past Ive just connected up aligator

clips

etc and really is unsafe. So Im going to put a switch and outlet on a

board

to do it right.

Im not sure exactly where to put the fuse however. To some degree I
know

it

could go anywhere. But really if something goes wrong I suppose you
want

the

whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I

think is

the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3
for

3

possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the

first

time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)



Looks good. However, what's the point of the fuse? Your house should
have a circuit breaker.

If you install a ground fault interrupter plug, that will give you some
added protection should you touch the wrong wire while standing in a
puddle of salt water connected to pipe leading to ground. It won't help
you if you complete a circuit between hot and neutral, but if you keep
one hand behind your back, the worst that will happen is you burn your

hand.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

Thanks for your comments.

I suppose the point of the fuse (I would use one of those little 1Amp
Glass
fuses) is to give added protection. Have it blow at a lower level. Nothing
I
do is going to draw much power. I suppose I was also thinking that it
might
?? save the device that I was connected to from blowing sky high. I know
that 1 Amp in its self can KILL you and Im just trying to be cautious. Why
put in a bigger fuse that you need?
As well there are other things on that circuit. I would like to prevent
everything on that house fuse from being shut down needlessly.

Comments ??
Click to expand...

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:RqSdnfUYYbruIJ_fRVn-iQ@comcast.com...
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=42881&item=3871828713&rd=1&tc=photo

Art wrote:
FWIW: Have you even given an isolation transformer any consideration, at
least for safety sake? The fuse or GFI is a good idea but isolating your
test bench may be a bit more prudent, IMHO. BTW if you do use an
isolation
transformer, do not overload the circuitry or you will just toast it.
"Trudeau" <Trudeau@123.com> wrote in message
news:UK-dnZxZGenM6J_fRVn-qw@rogers.com...

"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:n_adnec-bdpb7J_fRVn-iw@comcast.com...

Trudeau wrote:

Im building a little 120 Volt panel (for lack of a better word) to do

some

experiments with 120 Volts. In the past Ive just connected up aligator

clips

etc and really is unsafe. So Im going to put a switch and outlet on a

board

to do it right.

Im not sure exactly where to put the fuse however. To some degree I
know

it

could go anywhere. But really if something goes wrong I suppose you
want

the

whole thing to be shut down so all live wires are killed.

However others may have some other advice. Here is a diagram that I

think is

the best way to set it up.

To make it easier for discussion I have noted 3 points F1, F2 and F3
for

3

possible fuse points. F1 Seems like the most likely place.

Excuse my drawing. View in Notepad. I hope it shows up OK this is the

first

time I have put a diagram into the newsgroup.


.----F2-----.
| |
Small Fuse House | .-----. | .----------------.
F1 Switch | || |o--' | |
+ _ _/ | .o| +| | |
o-----o-o_/ \o--o/ o---. ||120AC| --------F3 -| Projects |
|| 0 | 120 V AC Out | |
- |'-----' To Projects | |
o-------------------------. | | |
=== | |
120 House current GND | |
'----------------'
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)



Looks good. However, what's the point of the fuse? Your house should
have a circuit breaker.

If you install a ground fault interrupter plug, that will give you some
added protection should you touch the wrong wire while standing in a
puddle of salt water connected to pipe leading to ground. It won't help
you if you complete a circuit between hot and neutral, but if you keep
one hand behind your back, the worst that will happen is you burn your

hand.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

Thanks for your comments.

I suppose the point of the fuse (I would use one of those little 1Amp
Glass
fuses) is to give added protection. Have it blow at a lower level.
Nothing
I
do is going to draw much power. I suppose I was also thinking that it
might
?? save the device that I was connected to from blowing sky high. I know
that 1 Amp in its self can KILL you and Im just trying to be cautious.
Why
put in a bigger fuse that you need?
As well there are other things on that circuit. I would like to prevent
everything on that house fuse from being shut down needlessly.

Comments ??







--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
Click to expand...
Thnaks again for your suggestions.
Could someone explain, ( Simple as you can ) what the advantage of an
isolation transformer would be in this project. As I understand it basically
you have a transformer that separates the 120 house into I suppose 120
coming from the other half of the transformer. (Is this called a 1 to 1). Im
not sure what the difference is. Unless as I come to think of it you are
reducing the amps from 15 house to say 1 or 2. I suppose this would have
some added safety.
Please Carify.

Thanks.
 
On Fri, 4 Feb 2005 09:25:45 -0600, "Trudeau" <Trudeau@123.com> wrote:


Thnaks again for your suggestions.
Could someone explain, ( Simple as you can ) what the advantage of an
isolation transformer would be in this project. As I understand it basically
you have a transformer that separates the 120 house into I suppose 120
coming from the other half of the transformer. (Is this called a 1 to 1). Im
not sure what the difference is. Unless as I come to think of it you are
reducing the amps from 15 house to say 1 or 2. I suppose this would have
some added safety.
Please Carify.
Click to expand...
---
The reason for the isolation transformer is to place a galvanic
barrier between whatever's plugged into the output of the transformer
and the mains. That way, the likelihood that you'll kill yourself or
the equipment you're working on/with will be made somewhat smaller.

--
John Fields
 
On Fri, 4 Feb 2005 12:23:58 -0600, "Trudeau" <Trudeau@123.com> wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:i25701t8rfm5qn4sonfnioeav1h2ditn45@4ax.com...
On Fri, 4 Feb 2005 09:25:45 -0600, "Trudeau" <Trudeau@123.com> wrote:


Thnaks again for your suggestions.
Could someone explain, ( Simple as you can ) what the advantage of an
isolation transformer would be in this project. As I understand it
basically
you have a transformer that separates the 120 house into I suppose 120
coming from the other half of the transformer. (Is this called a 1 to 1).
Im
not sure what the difference is. Unless as I come to think of it you are
reducing the amps from 15 house to say 1 or 2. I suppose this would have
some added safety.
Please Carify.

---
The reason for the isolation transformer is to place a galvanic
barrier between whatever's plugged into the output of the transformer
and the mains. That way, the likelihood that you'll kill yourself or
the equipment you're working on/with will be made somewhat smaller.

--
John Fields

Thanks for that.

I'm a little unclear on what the Galvanic barrier does.

I ve done a little research and learned that a galvanic process is a
process that creates electricity. eg electricity in frogs legs.
Secondly I have always know that when you put certain metals together that
you get corrosion. I have now learned the name for this is a Galvanic
Process.
As far as the discussion at hand I have found that a Galvanic Barrier in a
transformer :

A. Galvanic barrier has no metal metal contact, Well Yes of course its a
transformer. It uses fields to pass the current and air as the barrier.
Click to expand...
---
Well, only partly. The insulation on the magnet wire and the nylon
walls of the bobbin separating the primary and secondary (if the
transformer is wound that way) do the galvanic isolation.
---

I guess that not being directly connected to the mains is good. But its still
120volts.
B. A Galvanic barrier cuts down on noise. Not sure its important in this
case.
C. That a G.B. prevents ground loops. This I can see as being important.

Am I right here. Are there more reasons to use the isolation transformer?
I guess my confusion is that if the voltage coming into the transformer is
the same coming out accept for the fact that it is cleaner and perhaps
exactly 120 Volts. Im not sure what more added safety it adds, accept for
the things I noted above. Sorry to be dense. What am I missing?
Click to expand...
---
If you're working with mains hot and neutral directly, without going
through a transformer and you get hot and neutral reversed, the
chassis of what you're working on could be connected to mains hot with
the embarrassing result that you could fry a scope probe as soon as
you clip the probe's ground to chassis or to whatever you thought was
ground in the circuit. Worse, you could be holding on to the chassis
when you grab the alligator clip... Interpose an isolation
transformer between the DUT (device under test) and the mains and
those problems go away. Of course you'll still have 120V coming out
of the transformer, but if you don't know enough not to grab ahold of
that, you'll probably be a candidate for a Darwin award soon,
anyway!^)

--
John Fields
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:i25701t8rfm5qn4sonfnioeav1h2ditn45@4ax.com...
On Fri, 4 Feb 2005 09:25:45 -0600, "Trudeau" <Trudeau@123.com> wrote:


Thnaks again for your suggestions.
Could someone explain, ( Simple as you can ) what the advantage of an
isolation transformer would be in this project. As I understand it
basically
you have a transformer that separates the 120 house into I suppose 120
coming from the other half of the transformer. (Is this called a 1 to 1).
Im
not sure what the difference is. Unless as I come to think of it you are
reducing the amps from 15 house to say 1 or 2. I suppose this would have
some added safety.
Please Carify.

---
The reason for the isolation transformer is to place a galvanic
barrier between whatever's plugged into the output of the transformer
and the mains. That way, the likelihood that you'll kill yourself or
the equipment you're working on/with will be made somewhat smaller.

--
John Fields
Click to expand...
Thanks for that.

I'm a little unclear on what the Galvanic barrier does.

I ve done a little research and learned that a galvanic process is a
process that creates electricity. eg electricity in frogs legs.
Secondly I have always know that when you put certain metals together that
you get corrosion. I have now learned the name for this is a Galvanic
Process.
As far as the discussion at hand I have found that a Galvanic Barrier in a
transformer :

A. Galvanic barrier has no metal metal contact, Well Yes of course its a
transformer. It uses fields to pass the current and air as the barrier. I
guess that not being directly connected to the mains is good. But its still
120volts.
B. A Galvanic barrier cuts down on noise. Not sure its important in this
case.
C. That a G.B. prevents ground loops. This I can see as being important.

Am I right here. Are there more reasons to use the isolation transformer?
I guess my confusion is that if the voltage coming into the transformer is
the same coming out accept for the fact that it is cleaner and perhaps
exactly 120 Volts. Im not sure what more added safety it adds, accept for
the things I noted above. Sorry to be dense. What am I missing?

Regards
 
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