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#1
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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! |
#2
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FYI: Circuit Breaker Safety Recall
Mine doesn't. All loads are switched or controlled by other than the circuit
breakers. Rusty O |
#3
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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 |
#4
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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! |
#5
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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 |
#6
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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 |
#7
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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 |
#8
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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 |
#9
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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 |
#10
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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 |
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