FYI: Circuit Breaker Safety Recall
 

Thanks for the heads up.

Boy, here's a hot one:
"Do not use the T-1 Circuit Breaker as a switch"

Name 2 boats that DON'T use circuit breakers for switches.....(c;



On Fri, 12 Mar 2004 10:07:17 -0500, Sir Spamalot
wrote:

Check out the following link for detailed info:

http://www.bluesea.com/T-1_recall_notice.htm



___________________________
NOSPAM: Please remove the "my" in "comcast" to reply.


Larry W4CSC
POWER is our friend!

FYI: Circuit Breaker Safety Recall
 

Mine doesn't. All loads are switched or controlled by other than the circuit
breakers.

Rusty O

FYI: Circuit Breaker Safety Recall
 

Waste of switches. Breakers make fine switches. Don't know where
Larry is coming from on this one (as usual). The problem with the
T1 breaker is it is not idiot proof. If you hold the breaker in the on
position it holds the circuit closed rather then interrupting again like a
normal magnetic breaker will. I believe that the older thermal breakers
always behaved this way but I'm not sure. In any case, only a moron
would hold a breaker closed, but then again there seems to be an
unlimited supply of morons on boats these days :)

Doug
s/v Callista

"Rusty O" wrote in message
hlink.net...
Mine doesn't. All loads are switched or controlled by other than the
circuit
breakers.

Rusty O

FYI: Circuit Breaker Safety Recall
 

Larry,
They do make circuit breakers intended for switch duty. If I recall
they're a "S" label on the circuit breaker.
Paul

"Larry W4CSC" wrote in message
...
Thanks for the heads up.

Boy, here's a hot one:
"Do not use the T-1 Circuit Breaker as a switch"

Name 2 boats that DON'T use circuit breakers for switches.....(c;



On Fri, 12 Mar 2004 10:07:17 -0500, Sir Spamalot
wrote:

Check out the following link for detailed info:

http://www.bluesea.com/T-1_recall_notice.htm



___________________________
NOSPAM: Please remove the "my" in "comcast" to reply.


Larry W4CSC
POWER is our friend!

FYI: Circuit Breaker Safety Recall
 

Doug,
All circuit breakers are not designed to be used as switches. Actually
they aren't guaranteed to work more than once, but I've know them to work
many times after being tripped repeatedly. They do make circuit breakers
that are intended to be used as a switch, I believe they have an "S"
designation on the breaker. If I were replacing circuit breakers I'd get
GFCI (ground fault circuit interrupter). They're a bit more but around the
water it seems like a good investment.
Paul

"Doug Dotson" wrote in message
...
Waste of switches. Breakers make fine switches. Don't know where
Larry is coming from on this one (as usual). The problem with the
T1 breaker is it is not idiot proof. If you hold the breaker in the on
position it holds the circuit closed rather then interrupting again like a
normal magnetic breaker will. I believe that the older thermal breakers
always behaved this way but I'm not sure. In any case, only a moron
would hold a breaker closed, but then again there seems to be an
unlimited supply of morons on boats these days :)

Doug
s/v Callista

"Rusty O" wrote in message
hlink.net...
Mine doesn't. All loads are switched or controlled by other than the
circuit
breakers.

Rusty O

FYI: Circuit Breaker Safety Recall
 

I assumed that the dicussion was related to breakers commonly
used on boats. ie Magnetic breakers these days. Breakers that
aren't guaranteed to work more than once would be pretty useless.
I think they are traditionally known as fuses :) GFCI breakers
are for AC. The T1 breaker that started this thread is for
12 VDC.

Doug
s/v Callista

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
All circuit breakers are not designed to be used as switches. Actually
they aren't guaranteed to work more than once, but I've know them to work
many times after being tripped repeatedly. They do make circuit breakers
that are intended to be used as a switch, I believe they have an "S"
designation on the breaker. If I were replacing circuit breakers I'd get
GFCI (ground fault circuit interrupter). They're a bit more but around the
water it seems like a good investment.
Paul

"Doug Dotson" wrote in message
...
Waste of switches. Breakers make fine switches. Don't know where
Larry is coming from on this one (as usual). The problem with the
T1 breaker is it is not idiot proof. If you hold the breaker in the on
position it holds the circuit closed rather then interrupting again like
a
normal magnetic breaker will. I believe that the older thermal breakers
always behaved this way but I'm not sure. In any case, only a moron
would hold a breaker closed, but then again there seems to be an
unlimited supply of morons on boats these days :)

Doug
s/v Callista

"Rusty O" wrote in message
hlink.net...
Mine doesn't. All loads are switched or controlled by other than the
circuit
breakers.

Rusty O

FYI: Circuit Breaker Safety Recall
 

Doug,
Thanks for the correction, I was referring to AC breakers. Although I
wasn't aware there are specific breakers for DC. In machine control we don't
have breakers that are specific to DC or AC. 10 amps is 10 amps regardless
if it's AC or DC. I believe the breakers I'm familiar with are bimetal in
nature, if the amps pulled go over their rated value, the bimetal strip
heats up to the point it trips the breaker. The bimetal strip is a bonded
piece that has one type of metal on one side and a different type on the
other. The metals have a different rate of expansion as it heats up from the
current passing through it bends in an arc. If it bends far enough it trips
the breaker. As now the current is stopped, the bimetal cools allowing the
breaker to be reset.
Paul

"Doug Dotson" wrote in message
...
I assumed that the dicussion was related to breakers commonly
used on boats. ie Magnetic breakers these days. Breakers that
aren't guaranteed to work more than once would be pretty useless.
I think they are traditionally known as fuses :) GFCI breakers
are for AC. The T1 breaker that started this thread is for
12 VDC.

Doug
s/v Callista

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
All circuit breakers are not designed to be used as switches.
Actually
they aren't guaranteed to work more than once, but I've know them to
work
many times after being tripped repeatedly. They do make circuit breakers
that are intended to be used as a switch, I believe they have an "S"
designation on the breaker. If I were replacing circuit breakers I'd get
GFCI (ground fault circuit interrupter). They're a bit more but around
the
water it seems like a good investment.
Paul

"Doug Dotson" wrote in message
...
Waste of switches. Breakers make fine switches. Don't know where
Larry is coming from on this one (as usual). The problem with the
T1 breaker is it is not idiot proof. If you hold the breaker in the on
position it holds the circuit closed rather then interrupting again
like
a
normal magnetic breaker will. I believe that the older thermal
breakers
always behaved this way but I'm not sure. In any case, only a moron
would hold a breaker closed, but then again there seems to be an
unlimited supply of morons on boats these days :)

Doug
s/v Callista

"Rusty O" wrote in message
hlink.net...
Mine doesn't. All loads are switched or controlled by other than the
circuit
breakers.

Rusty O

FYI: Circuit Breaker Safety Recall
 

The difference I was referring to was in GFCI which is a strictly
an AC device. The bimetal breakers are thermal breakers. Pretty
much obsolete in the boating world. Magnetic breakers seem to
be the norm now. I had a thermal breaker panel on my boat when I bought
it. The whole panel would sometime get almost too hot to touch
when loaded heavily.

Doug
s/v Callista

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
Thanks for the correction, I was referring to AC breakers. Although I
wasn't aware there are specific breakers for DC. In machine control we
don't
have breakers that are specific to DC or AC. 10 amps is 10 amps regardless
if it's AC or DC. I believe the breakers I'm familiar with are bimetal in
nature, if the amps pulled go over their rated value, the bimetal strip
heats up to the point it trips the breaker. The bimetal strip is a bonded
piece that has one type of metal on one side and a different type on the
other. The metals have a different rate of expansion as it heats up from
the
current passing through it bends in an arc. If it bends far enough it
trips
the breaker. As now the current is stopped, the bimetal cools allowing the
breaker to be reset.
Paul

"Doug Dotson" wrote in message
...
I assumed that the dicussion was related to breakers commonly
used on boats. ie Magnetic breakers these days. Breakers that
aren't guaranteed to work more than once would be pretty useless.
I think they are traditionally known as fuses :) GFCI breakers
are for AC. The T1 breaker that started this thread is for
12 VDC.

Doug
s/v Callista

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
All circuit breakers are not designed to be used as switches.
Actually
they aren't guaranteed to work more than once, but I've know them to
work
many times after being tripped repeatedly. They do make circuit
breakers
that are intended to be used as a switch, I believe they have an "S"
designation on the breaker. If I were replacing circuit breakers I'd
get
GFCI (ground fault circuit interrupter). They're a bit more but around
the
water it seems like a good investment.
Paul

"Doug Dotson" wrote in message
...
Waste of switches. Breakers make fine switches. Don't know where
Larry is coming from on this one (as usual). The problem with the
T1 breaker is it is not idiot proof. If you hold the breaker in the
on
position it holds the circuit closed rather then interrupting again
like
a
normal magnetic breaker will. I believe that the older thermal
breakers
always behaved this way but I'm not sure. In any case, only a moron
would hold a breaker closed, but then again there seems to be an
unlimited supply of morons on boats these days :)

Doug
s/v Callista

"Rusty O" wrote in message
hlink.net...
Mine doesn't. All loads are switched or controlled by other than
the
circuit
breakers.

Rusty O

FYI: Circuit Breaker Safety Recall
 

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
Thanks for the correction, I was referring to AC breakers. Although I
wasn't aware there are specific breakers for DC. In machine control we
don't
have breakers that are specific to DC or AC.


Not exactly. When a contact opens, either in a switch or a circuit breaker,
the metallic conductors move from a condition of forced mechanical
compression to a condition of separation so large as to preclude a voltage
breakdown of the (maybe air) gap.

In the first condition, the resistance of the connection is very low, so the
Ohmic heating (I*I*R) is very low (due to very low resistance). In the last
condition, the Ohmic heating is also very low (due to very low current).

But in between those two conditions, all hell breaks loose. As the contacts
just begin to lose touch, the resistance goes up, and the heating goes up as
its square. A bit of the contacts melt, then vaporize, and the current is
carried by a (relatively) high resistance plasma (very hot). As the contacts
move further apart, a visible arc (metal & air heated till they glow) can be
seen. The heating is so severe that if the contacts were reclosed at this
point, they could very easily weld together. If the contacts aren't pulled
apart quickly, the arc may melt the contact surfaces, melt the supporting
structure, or char and burn the nearby insulating materials. As the gap
widens, the distance eventually becomes too wide to sustain the arc, and it
finally extinguishes.

All this happens to even the smallest switch contacts, even if the arcing is
on a microscopic scale.

So what is the difference between switching AC & DC currents? The DC current
is being driven by a constant voltage, so the arc extinguishes only when the
gap gets wide enough. But the AC current is being driven by a voltage that
approaches zero twice every cycle (for 60 Hz, this is about every 8
milliseconds). So, with AC, the arc can be extinguished by the voltage
dropping to zero even faster than the contacts can swing open far enough to
otherwise extinguish the arc.

Simply put, when you switch DC, it's always a "hard" interruption. But the
AC current is only strong during part of the sine cycle, so your odds of
switching at the maximum are less. And, the voltage and current drop to zero
every 1/120 of a second, providing a "self-extinguishing" effect too.
Switching DC is just harder duty than switching AC, so many switches and
breakers designed for AC duty don't even have a published DC capability.
(And switching DC on an inductive load, like a motor, is even worse.)

Ed
wb6wsn

FYI: Circuit Breaker Safety Recall
 

Doug,
Again thanks for the information. I wasn't aware of the difference, I
guess that's something I'll have to be on the lookout for when I shop for a
boat.
Paul

"Doug Dotson" wrote in message
...
The difference I was referring to was in GFCI which is a strictly
an AC device. The bimetal breakers are thermal breakers. Pretty
much obsolete in the boating world. Magnetic breakers seem to
be the norm now. I had a thermal breaker panel on my boat when I bought
it. The whole panel would sometime get almost too hot to touch
when loaded heavily.

Doug
s/v Callista

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
Thanks for the correction, I was referring to AC breakers. Although
I
wasn't aware there are specific breakers for DC. In machine control we
don't
have breakers that are specific to DC or AC. 10 amps is 10 amps
regardless
if it's AC or DC. I believe the breakers I'm familiar with are bimetal
in
nature, if the amps pulled go over their rated value, the bimetal strip
heats up to the point it trips the breaker. The bimetal strip is a
bonded
piece that has one type of metal on one side and a different type on the
other. The metals have a different rate of expansion as it heats up from
the
current passing through it bends in an arc. If it bends far enough it
trips
the breaker. As now the current is stopped, the bimetal cools allowing
the
breaker to be reset.
Paul

"Doug Dotson" wrote in message
...
I assumed that the dicussion was related to breakers commonly
used on boats. ie Magnetic breakers these days. Breakers that
aren't guaranteed to work more than once would be pretty useless.
I think they are traditionally known as fuses :) GFCI breakers
are for AC. The T1 breaker that started this thread is for
12 VDC.

Doug
s/v Callista

"Paul Schilter" paulschilter@comcast,dot,net wrote in message
...
Doug,
All circuit breakers are not designed to be used as switches.
Actually
they aren't guaranteed to work more than once, but I've know them to
work
many times after being tripped repeatedly. They do make circuit
breakers
that are intended to be used as a switch, I believe they have an "S"
designation on the breaker. If I were replacing circuit breakers I'd
get
GFCI (ground fault circuit interrupter). They're a bit more but
around
the
water it seems like a good investment.
Paul

"Doug Dotson" wrote in message
...
Waste of switches. Breakers make fine switches. Don't know where
Larry is coming from on this one (as usual). The problem with the
T1 breaker is it is not idiot proof. If you hold the breaker in
the
on
position it holds the circuit closed rather then interrupting
again
like
a
normal magnetic breaker will. I believe that the older thermal
breakers
always behaved this way but I'm not sure. In any case, only a
moron
would hold a breaker closed, but then again there seems to be an
unlimited supply of morons on boats these days :)

Doug
s/v Callista

"Rusty O" wrote in message
hlink.net...
Mine doesn't. All loads are switched or controlled by other than
the
circuit
breakers.

Rusty O