Battery Switches are rated under UL standard 1107*, which defines two important switch ratings (current being common to both):
* There is an equivalent CE certification.
Continuous Duty Rating
: Amperage that can be conducted for 1 hour without raising the terminal temperature more than 100 degrees C or the housing temperature more than 65 degrees C.
Intermittent Duty Rating
: Amperage that can be conducted for 5 minutes without raising the terminal temperature more than 100 degrees C or the housing temperature more than 65 degrees C.
Current carrying capacity, measured in amps, is the maximum load that a switch will carry, with the contacts in a closed
position. When you switch between positions (make or break), an electrical arc
occurs, which causes contact wear. A switch with the contacts closed has no arc
, and the carrying capacity is higher.
Make & Break Arcing:
Make is when the switch is turned On (the circuit is 'made'), and break is when the switch is turned Off (the circuit is 'broken'). Arcing is greater on Break than on Make, and greater on Direct Current (DC) than Alternating Current (AC). The arc produced by a DC voltage will be greater and last longer than an AC voltage because DC current has a constant value in relation to ground and zero. AC current has a value that is always rising or falling in relation to zero. Whenever it reaches zero (120 times a second) in cannot produce an arc. Quick Make Quick Break (QMQB) switches are designed to make or break circuits in less than 5 milliseconds, as recommended for use on DC circuits. For this reason, any switch used in a dc circuit should be specifically rated for dc operation**. Battery switches are “Make before Break” type (connects the new circuit before disconnecting the old), in order to avoid an open circuit for the engine alternator, which can cause extreme voltages that can damage the alternator and accessory electronics
** According to Eaton, a 120VAC switch current rating will be roughly equivalent to the 28VDC current rating.
Eaton Switch Training Module:
Cole Hersey, Blue Sea Systems, & others rate their switches under UL Standard 1107.
I suspect that the only difference between Blue Sea & Cole Hersey is that Blue Sea notes the conditions under which their switch meets the standard (with 4/0 cables
connected) and Cole Hersey appears not to. I don’t have the standard, but I’m fairly certain that the testing is performed under defined installation
conditions, which would include cable sizes.
Blue Sea also offers an “Engine Starting Standard”.
Battery Switch Ratings Explained: http://www.bluesea.com/Article_detai...n_ID=145&id=96
Blue Sea Systems Engine Starting Standard: