Why are some toggle or limit switches,for instance, rated 20 amp 125 volt but only 10 amp 250 volt? Why do they not maintain their higher amperage rating for the higher voltage? Or are they trying to express wattage rating with voltage and amperage and if so why don't they just put the wattage rating on it instead?
switch ratings
- Thread starter jap2525
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- Semi-Retired Electrical Engineer
Re: switch ratings
A current rating is based on the cross-sectional area of the current-carrying components. A voltage rating is based on the ability of the insulation system to prevent leakage current from passing from the current-carrying parts to the outside world. A power rating is based on the ability of the component to dissipate heat.
It seems to me that you are describing a power rating. However, most users would not immediately recognize that fact. Switches are purchased by people who do not know that power is the product of current and voltage. That is sad, but true. I suspect that the manufacturers are merely making it easier for all of their customers to properly select the right switch for the right application.
A current rating is based on the cross-sectional area of the current-carrying components. A voltage rating is based on the ability of the insulation system to prevent leakage current from passing from the current-carrying parts to the outside world. A power rating is based on the ability of the component to dissipate heat.
It seems to me that you are describing a power rating. However, most users would not immediately recognize that fact. Switches are purchased by people who do not know that power is the product of current and voltage. That is sad, but true. I suspect that the manufacturers are merely making it easier for all of their customers to properly select the right switch for the right application.
Re: switch ratings
This marking is also on icecube relays.What is the difference in breaking 120 volts through (1)contact or 240 volts through (2) contacts? You still only have 120 volts through both contacts and should be able to maintain the higher amperage rating of the 120 volts even though 240 volts is being controlled through the relay.
This marking is also on icecube relays.What is the difference in breaking 120 volts through (1)contact or 240 volts through (2) contacts? You still only have 120 volts through both contacts and should be able to maintain the higher amperage rating of the 120 volts even though 240 volts is being controlled through the relay.
Re: switch ratings
contacts in close proximity are subject to flash over . Initial arcing upon contact break may create heated air that is ionized allowing current from one line to the other Flash Over. or dead 240V short.Lower current capacity in this application may reduce this event.
contacts in close proximity are subject to flash over . Initial arcing upon contact break may create heated air that is ionized allowing current from one line to the other Flash Over. or dead 240V short.Lower current capacity in this application may reduce this event.
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