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16-01-2011, 07:28
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#16
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Registered User
Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,367
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Lets not confuse the originator of this thread. All he wants to do is switch a couple of miliamps on an LED mast light although I don't really know why a switch is needed at the mast base. I suspect the light is already on a proper circuit breaker and controled by a switch somewhere (binacle?). If he needs a switch - go to West and buy a marine rated switch. The packages are clearly labled as to the configuration. You can panel mount and thread on a water-proofing condom if its outside. All of these will easily handle the load.
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16-01-2011, 08:32
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#17
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,384
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__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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16-01-2011, 08:41
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#18
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,384
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__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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16-01-2011, 09:08
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#19
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Registered User
Join Date: Apr 2003
Location: back on Gold Coast after swallowing the anchor
Boat: boat less ATM
Posts: 318
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Quote:
Originally Posted by GordMay
A resistor-capacitor network called a "snubber" can be connected in parallel with a switch contact to reduce contact arcing.
Wetting current is the minimum amount of electric current necessary for a switch contact to carry in order for it to be self-cleaning. Normally this value is far below the switch's maximum current rating. Accordingly, switches with vastly overrated (for the application) contacts should be avoided.
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Gee, Gord, I am so glad you straightened that out in my mind
BTW thanks for all the contacts for the 12 V switches but unfortunately I live in Oz. I like the Contura switches but West Marine wanted to charge me $80 just for freight to here.
I have been busy ggogling but 12 V DPDT , centre off switches seem very hard to find downunder. I have been to four large auto supply places and the children serving there look at me like I am speaking jibberish.
Into the Too Hard Basket (THB) with 12 V switch- so I will give the 240 V one a go.
I need the DPDT switch so I can run the anchor light off the same wiring as the nav masthead light, as per Bebi's wiring diagram.
__________________
Paul & Kaspar de Wonda Dog
S/V "Pelican V"
"Trust not a living soul and step warily around the dead"
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16-01-2011, 10:00
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#20
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֍֎֍֎֍֎֍֎֍֎
Join Date: Apr 2006
Posts: 15,136
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Lifetech, other engineers and manufacturers disagree with your dertaing:
"DC Rule of Thumb
For those switches that list an AC voltage rating only, the "DC Rule of Thumb" can be applied for determining the switch's maximum DC current rating. This "rule" states the highest amperage on the switch should perform satisfactorily up to 30 volts DC. For example, a switch which is rated at 10A 250VAC; 15A 125VAC; 3/4HP 125-250VAC, will be likely to perform satisfactorily at 15 amps up to 30 volts DC (VDC)."
[from Products - Switches - Learn More ]
I suspect you are not compensating for the radical difference in the voltages. Dropping down from 240VAC to 12VDC makes a big difference.
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16-01-2011, 10:55
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#21
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Registered User
Join Date: May 2009
Location: Massachusetts
Boat: 40' Silverton Aftcabin with twin Crusaders
Posts: 1,791
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Quote from GordMay:
A resistor-capacitor network called a "snubber" can be connected in parallel with a switch contact to reduce contact arcing.
Wetting current is the minimum amount of electric current necessary for a switch contact to carry in order for it to be self-cleaning. Normally this value is far below the switch's maximum current rating. Accordingly, switches with vastly overrated (for the application) contacts should be avoided. Attached Images
Right again Gordie. You must be a secret electrical, mechanical & chemical engineer!!!
Foggy
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16-01-2011, 11:03
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#22
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Registered User
Join Date: May 2009
Location: Massachusetts
Boat: 40' Silverton Aftcabin with twin Crusaders
Posts: 1,791
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Quote:
Originally Posted by Nicholson58
Lets not confuse the originator of this thread. All he wants to do is switch a couple of miliamps on an LED mast light although I don't really know why a switch is needed at the mast base. I suspect the light is already on a proper circuit breaker and controled by a switch somewhere (binacle?). If he needs a switch - go to West and buy a marine rated switch. The packages are clearly labled as to the configuration. You can panel mount and thread on a water-proofing condom if its outside. All of these will easily handle the load.
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Nicholson-- Yes I understand but Gordie is right pointing out that there is a minimum current and for that matter a voltage to make the contacts "make"
For example, if you take a box of common household toggle switches and check for continuity when the switch is in the on position using a high impedance ohm meter, you might find some with no continuity even though the switch is actually a good switch when 120 volts is applied.
Foggy
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16-01-2011, 11:08
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#23
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Registered User
Join Date: May 2009
Location: Massachusetts
Boat: 40' Silverton Aftcabin with twin Crusaders
Posts: 1,791
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Quote:
Originally Posted by hellosailor
Lifetech, other engineers and manufacturers disagree with your dertaing:
"DC Rule of Thumb
For those switches that list an AC voltage rating only, the "DC Rule of Thumb" can be applied for determining the switch's maximum DC current rating. This "rule" states the highest amperage on the switch should perform satisfactorily up to 30 volts DC. For example, a switch which is rated at 10A 250VAC; 15A 125VAC; 3/4HP 125-250VAC, will be likely to perform satisfactorily at 15 amps up to 30 volts DC (VDC)."
[from Products - Switches - Learn More ]
I suspect you are not compensating for the radical difference in the voltages. Dropping down from 240VAC to 12VDC makes a big difference.
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That is utter nonsense. If a switch interrupts a DC current in an inductive circuit without an arc protection circuit in place, it is likely to arc. And if the inductor is large, it WILL arc. Be careful of "rules of thumb."
Foggy
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16-01-2011, 11:17
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#24
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Moderator
Join Date: Jul 2007
Boat: Bestevaer.
Posts: 14,678
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Quote:
Originally Posted by svstrider
Gee, Gord, I am so glad you straightened that out in my mind
BTW thanks for all the contacts for the 12 V switches but unfortunately I live in Oz. I like the Contura switches but West Marine wanted to charge me $80 just for freight to here.
I have been busy ggogling but 12 V DPDT , centre off switches seem very hard to find downunder. I have been to four large auto supply places and the children serving there look at me like I am speaking jibberish.
Into the Too Hard Basket (THB) with 12 V switch- so I will give the 240 V one a go.
I need the DPDT switch so I can run the anchor light off the same wiring as the nav masthead light, as per Bebi's wiring diagram.
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Try Jaycar.
Cat no ST-0576 add a rubber boot to help waterproof
Or electric boat parts in sydney.
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16-01-2011, 12:21
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#25
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,384
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Quote:
Originally Posted by hellosailor
... "DC Rule of Thumb
For those switches that list an AC voltage rating only, the "DC Rule of Thumb" can be applied for determining the switch's maximum DC current rating. This "rule" states the highest amperage on the switch should perform satisfactorily up to 30 volts DC. For example, a switch which is rated at 10A 250VAC; 15A 125VAC; 3/4HP 125-250VAC, will be likely to perform satisfactorily at 15 amps up to 30 volts DC (VDC)." ...
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I’ll certainly bow to the expertise of Carling, especially regarding their products. I’d be careful about applying their 30VDC Rule of Thumb to products of unknown quality.
➥ Products - Switches - Learn More
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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16-01-2011, 12:26
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#26
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,384
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Ask Cole Hersee, Australia & New Zealand*, where you might locate a Cole Hersee #56006-01 (or equal) switch.
* Britax Automotive Equipment
79 Crockford Street
Northgate, Queensland 4013
Email: bae@britaxae.com.au
Tel: 61 73000 1900
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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16-01-2011, 14:23
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#27
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֍֎֍֎֍֎֍֎֍֎
Join Date: Apr 2006
Posts: 15,136
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Gird-
" I’d be careful about applying their 30VDC Rule of Thumb to products of unknown quality."
Yup. But we come back again to the point here: The OP has switches rated for 20x higher voltage and 5x higher amperage than he needs. All of which is so far beyond his needs that the finer points of engineering can be simplified out of the picture. A household lighting switch is generally overkill for nav lights, and that goes all the more so so an LED nav light.
As if I think any two-buck Made In China 12vdc switch from Rat Shack or other sources is going to hold up any better? Haha, engineering, right, might as well be Greek Mythology these days. Heck, I've got "JAN" WW2 surplus switches that are still working very nicely, bought on Radio Row before there was a WTC. It's just a wee bit harder to find them on any market at any price these days, isn't it?
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16-01-2011, 15:07
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#28
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,384
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Quote:
Originally Posted by hellosailor
Gird-
... The OP has switches rated for 20x higher voltage and 5x higher amperage than he needs. All of which is so far beyond his needs that the finer points of engineering can be simplified out of the picture ...
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If you say so.
I might be tempted to argue otherwise, but I've forgotten more about switch technology than I can recall.
As I said, I'd certainly accept a manufacturer's advise on their product.
G ord
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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16-01-2011, 16:36
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#29
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Registered User
Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,367
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Marine LED Masthead and Running Light Bulb Replacement Assembly
0.16 AMPS AT 12 VOLTS
Does anyone really think that any marine DPDT toggle switch (or automotive) will fail to make or break this circuit? The mechanics of the switch will wear out before any electrical difficulty shows.
WEST switch & water resistant cover I just bought for my LED compass light 0.05 amp. This will work. You can also shop Grainger or McMaster Carr or many other electrical, preferably marine, sources.
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16-01-2011, 16:59
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#30
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Marine Service Provider
Join Date: Mar 2010
Posts: 86
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Quote:
Originally Posted by svstrider
BTW thanks for all the contacts for the 12 V switches but unfortunately I live in Oz.
I have been busy ggogling but 12 V DPDT , centre off switches seem very hard to find downunder.
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svstrider, there are numerous places in Oz where you can buy DPDT switches. It sounds like you just don't know where to look. Just a few suppliers you can try are-
Jaycar electronics
Altronics
RS Components
Farnell Components
John R Turks
TLE Electrical
There are plenty more but the above all have sales offices in most states.
__________________
LiFeTech Energy -When quality and performance is what matters most.
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