250 volts rating

Status
Not open for further replies.
mbrooke

mbrooke

Batteries Included
Location
United States
Occupation
Technician
How is the 250 volt rating derived on switches, receptacles, capacitors and other equipment?

Is 250 volts the absolute maximum voltage, or does it take into account plus 5% meaning 262 volts or 110% meaning 275 volts maximum voltage?



61n4lswpvkL._SL1500_.jpg
 
100915-2337 EDT

Experience, testing, historical information, environment, and expected life. Generally specs are well below a sharp threshold point.

Mylar has a high dielectric strength, but it is both temperature and thickness dependent. You would not make a product, capacitor for example, with a stress level anywhere close to the said breakdown level. And the criteria will also be dependent upon expected life, ambient pressure, and other factors. AC or DC should also make a difference.

On switches and other similar devices over the surface breakdown may become a major factor along with altitude.

.
 
That would normally be the maximum voltage, period.

Maybe we can give you a better answer if you tell us why you're asking.
 
Violation, no. The concern would be the cap's longevity on 240v.

f it pops, replace it one with with a higher voltage rating, like 450v.
 
Last edited:
LarryFine said:
Violation, no. The concern would be the cap's longevity on 240v.

f it pops, replace it one with with a higher voltage rating, like 450v.
Click to expand...



Is this for all equipment?

The thing is I see equipment listed 240 volts and 250 volts- yet there is no 250 volt system in existence.
 
Most things can take well over what they are marked at least for short time, if not they would be destroyed every time a transient voltage occurs or even during meg testing.

And remember that 240 AC is RMS volts, peak volts is about 339.
 
Capacitor voltage ratings are maximum working voltages. AC ratings are rms ratings. 250 VAC capacitors are used on 240 systems depending on the application. A motor starting capacitor normally does not see full line voltage, for example.
 
kwired said:
Most things can take well over what they are marked at least for short time, if not they would be destroyed every time a transient voltage occurs or even during meg testing.

And remember that 240 AC is RMS volts, peak volts is about 339.
Click to expand...

True, but you still have a peak in terms of dielectric breakdown and RMS in terms of energy dissipated from say a heating element.
 
Status
Not open for further replies.
Top