# Dielectric breakdown voltage of 47,300 volts! **URL:** \ **Category:** Factual Questions\ **Created:** [October 18, 2002, 10:45pm UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906 "2002-10-18T22:45:52Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Weeks](https://avatars.discourse-cdn.com/v4/letter/w/bbce88/32.png) [@Weeks](https://boards.straightdope.com/u/Weeks)\ **Post date:** [October 18, 2002, 10:45pm UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/1 "2002-10-18T22:45:52Z")
Yup, thats what it says on the label of a can of Spectracide PRO wasp and hornet killer! couldn’t find a link to the pro line, but take my word for it. Anybody able to decipher this mumbo jumbo? ---
**Author:** ![AgentofEvil](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@AgentofEvil](https://boards.straightdope.com/u/AgentofEvil)\ **Post date:** [October 18, 2002, 11:05pm UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/2 "2002-10-18T23:05:44Z")
Well, if you put a potential of greater than 47,300V across it, current would flow through it, otherwise it’s an insulator. What that has to do with bug spray, I don’t know. ---
**Author:** ![Saltire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saltire/32/553_2.png) [@Saltire](https://boards.straightdope.com/u/Saltire)\ **Post date:** [October 18, 2002, 11:44pm UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/3 "2002-10-18T23:44:02Z")
This is the stuff that sprays a 5-meter stream, so that you can kill a nest from a comfortable distance, right? I’m just guessing here, but they may be telling you that the stuff is safe to spray on a nest that’s hanging from a power line or transformer, as long as it isn’t carrying too high a potential. Not that I’d try it myself. ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [October 18, 2002, 11:59pm UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/4 "2002-10-18T23:59:25Z")
My guess would be that they are letting that known to you incase you want to add it to Capacitor or Transformer Oil. Donno, if they still use those capacitors with oil and transformer oil nowadays is mostly SF6. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [October 19, 2002, 12:12am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/5 "2002-10-19T00:12:33Z")
> [@](#): > > \*Originally posted by Saltire \* > \*\*…I’m just guessing here, but they may be telling you that the stuff is safe to spray on a nest that’s hanging from a power line or transformer, as long as it isn’t carrying too high a potential… \*\* Exactly. The company I work for sells something like this. The local power company buys it by the case. ---
**Author:** ![Weeks](https://avatars.discourse-cdn.com/v4/letter/w/bbce88/32.png) [@Weeks](https://boards.straightdope.com/u/Weeks)\ **Post date:** [October 19, 2002, 12:18am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/6 "2002-10-19T00:18:16Z")
Uh, I think I got it…wont fry you if you hit a hot line? ---
**Author:** ![Weeks](https://avatars.discourse-cdn.com/v4/letter/w/bbce88/32.png) [@Weeks](https://boards.straightdope.com/u/Weeks)\ **Post date:** [October 19, 2002, 12:22am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/7 "2002-10-19T00:22:42Z")
Thanks! ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [October 19, 2002, 1:41am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/8 "2002-10-19T01:41:53Z")
Nitpick 😃 The Units are inconsistent. It should be 47,300 V/in or V/mm or something. Its more of the Electric Field than the voltage that causes breakdown. ---
**Author:** ![octothorpe](https://avatars.discourse-cdn.com/v4/letter/o/b77776/32.png) [@octothorpe](https://boards.straightdope.com/u/octothorpe)\ **Post date:** [October 19, 2002, 5:52am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/9 "2002-10-19T05:52:51Z")
Originally posted by **andy\_fl** > [@](#): > > My guess would be that they are letting that known to you incase you want to add it to Capacitor or Transformer Oil. Donno, if they still use those capacitors with oil and transformer oil nowadays is mostly SF6. Transformer oil is basically the same as it has been for the last century; highly refined mineral oil. Although the gas SF[sub]6[/sub] (Sulfer Hexa-Flouride) is used extensively in the electric utility industry, it is used almost exclusively in ‘switching’ devices such as power circuit breakers, circuit switchers and the like. SF[sub]6[/sub] has outstanding insulating properties and allows a device to break an arc and maintain the ‘open’ in a much smaller area than air. As an example, 345KV will arc 109" in dry air. Using a ‘gas-blast’ breaker, SF[sub]6[/sub] will allow the device to break the arc and maintain the ‘open’ in 12.5". Transformers are filled with oil basically to help cool them. While it is true that the oil itself has good dielectric properties, this is actually a secondary consideration. To be used outdoors, the coils and core of a transformer must be housed in a watertight enclosure. The problem then becomes how to keep the transformer cool as the inefficiencies inherent in transformers manifest themselves in heat. While water would be adequate to the task of cooling, any but the purest water is conductive and, as such, would be unacceptable. A medium was needed that would provide the cooling properties while, at the same time, have excellent insulating properties. Highly refined mineral oil fit the bill nicely. # ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [October 19, 2002, 7:13am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/10 "2002-10-19T07:13:15Z")
> [@](#): > > \*Originally posted by octothorpe \* > \*\*Transformer oil is basically the same as it has been for the last century; highly refined mineral oil. \*\* Thanks octo, that was great information. However, transformer Oil **has changed** since the last century and the major change involves stopping the use of PCB’s (Polychlorinated Biphenyls) in the Oil. Lot of Environmental Firms are making a lot of money remediating sites contaminated with PCBs from Transformer Oils. ---
**Author:** ![honkytonkwillie](https://avatars.discourse-cdn.com/v4/letter/h/3da27b/32.png) [@honkytonkwillie](https://boards.straightdope.com/u/honkytonkwillie)\ **Post date:** [October 19, 2002, 8:01am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/11 "2002-10-19T08:01:26Z")
> [@](#): > > \*Originally posted by andy\_fl \* > \*\*Nitpick 😃 > > The Units are inconsistent. It should be 47,300 V/in or V/mm or something. Its more of the Electric Field than the voltage that causes breakdown. \*\* In this case, it’s 47,300V/5m, assuming its the same stuff **Saltire** is talking about. ---
**Author:** ![octothorpe](https://avatars.discourse-cdn.com/v4/letter/o/b77776/32.png) [@octothorpe](https://boards.straightdope.com/u/octothorpe)\ **Post date:** [October 19, 2002, 9:44am UTC](https://boards.straightdope.com/t/dielectric-breakdown-voltage-of-47-300-volts/132906/12 "2002-10-19T09:44:33Z")
b]andy\_fl\*\* I certainly can’t argue that a lot of companies are making a killing cleaning up PCB contaminated sites, but the _addition_ of PCBs, in itself, was a major change. PCBs were first added to transformers to help cut down on fires. At one point, some transformers were filled with nearly 100% PCBs (This concoction was more jelly than oil) and each maker had his own brand (i believe the Westinghouse brand was called _ **Askeral** _). By and large such transformers were the exception although many transformers contained small amounts of PCBs in the oil. If memory serves, any appartus that contains 250ppm or less of PCBs does not have to be removed from service although a device is not considered to be non-PCB unless it contains less than 1ppm. Thanks for showing the interest (and thanks for the compliment). I had considered mentioning this in my previous post, but didn’t really think that anyone would be interested. So much for assumptions… I’m still pondering your _units_ statement. I’m not sure, in this context, that units are required. The generally accepted tests for dielectric breakdown are the **ASTM D877** and **ASTM D1816**. If one or the other of these tests were used, then it would not be necessary to include units as the test parameters are very strictly defined. I will grant that, if this breakdown level was arrived at using one of these test, it should be noted on the label. #