# What does this mean? \[dielectric breakdown\] **URL:** \ **Category:** Factual Questions\ **Created:** [April 4, 2020, 10:09am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041 "2020-04-04T10:09:23Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![turtlescanfly](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@turtlescanfly](https://boards.straightdope.com/u/turtlescanfly)\ **Post date:** [April 4, 2020, 10:09am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/1 "2020-04-04T10:09:23Z")
Seen on a can of wasp and hornet spray (insecticide): “Dielectric breakdown voltage of 47,300 volts” I can’t for the life of me understand what that would mean in the context of a bug spray. Sent from my SM-G935V using Tapatalk ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [April 4, 2020, 10:24am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/2 "2020-04-04T10:24:23Z")
> [@turtlescanfly](#): > > Seen on a can of wasp and hornet spray (insecticide): > > “Dielectric breakdown voltage of 47,300 volts” > > I can’t for the life of me understand what that would mean in the context of a bug spray. > > Sent from my SM-G935V using Tapatalk It means that whatever the base material is, has an insulating factor of 47,300 volts. This means that it is safe to spray around uninsulated wires. It won’t catch fire. Unless for some reason they are conducting more than 47,300 volts. ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [April 4, 2020, 10:27am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/3 "2020-04-04T10:27:09Z")
nm double-post ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 4, 2020, 10:27am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/4 "2020-04-04T10:27:32Z")
Shockingly (heh, heh) a quick googling shows that this topic [has come up here before](https://boards.straightdope.com/sdmb/showthread.php?t=140183). ---
**Author:** ![turtlescanfly](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@turtlescanfly](https://boards.straightdope.com/u/turtlescanfly)\ **Post date:** [April 4, 2020, 10:30am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/5 "2020-04-04T10:30:44Z")
Thanks, that makes sense. Strange though I dont ever remember seeing a similar message on other sprays. Sent from my SM-G935V using Tapatalk ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [April 4, 2020, 12:37pm UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/6 "2020-04-04T12:37:09Z")
> [@Darren\_Garrison](#): > > Shockingly (heh, heh) a quick googling shows that this topic [has come up here before](https://boards.straightdope.com/sdmb/showthread.php?t=140183). 18 years later and they are still claiming the same breakdown voltage. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 4, 2020, 2:20pm UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/7 "2020-04-04T14:20:41Z")
47,300 volts over what distance? ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [April 4, 2020, 8:37pm UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/8 "2020-04-04T20:37:01Z")
> [@Chronos](#): > > 47,300 volts over what distance? The SI unit for volts per meter, but that’s an impractical range for insulators and such\*. So megavolts per meter gives a more rational [numeric range](https://en.wikipedia.org/wiki/Dielectric_strength#Breakdown_field_strength). Which is the same a kilovolts per millimeter\*\* which then leads to stuff being abbreviated as just kilovolts. So, perhap 47.3 KV/mm. Which seems high, IMHO, for a liquid with varied components. Just hope that it isn’t kilovolts per mil as that’s a whole 'nother range. - Either too many zeros or always having to put x10 exponents after. \*\* And millimeter is more intuitive when talking about insulating wires and such. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [April 5, 2020, 3:43am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/9 "2020-04-05T03:43:16Z")
And note that the same question (about volts per unit of distance?) was raised in the earlier thread too, and not entirely clearly answered there either. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 5, 2020, 6:20am UTC](https://boards.straightdope.com/t/what-does-this-mean-dielectric-breakdown/851041/10 "2020-04-05T06:20:13Z")
ASTM has specific test methods for determining the dielectric breakdown for pesticides and other materials.[Here’s a defining doc in .pdf](https://www.regulations.gov/contentStreamer?documentId=EPA-HQ-OPPT-2009-0151-0022&contentType=pdf), you can try to follow the maze to discover the test method details if you like, but it will come down to use of a particular test device with electrodes spaced at a specific distance to provide the V/m value.