Will it really arc in this situation?

[cjmillsnun]

We're going around in circles now.

Yes we are. I think we can all agree. The person in question was an idiot. Time to close the thread methinks.

 

[1018509]

Rubber is not a trustworthy insulation. On an elderly Hillman Imp I used to own the car wouldn't start one damp morning because the coil lead was earthing to the rubber radiator hose. If it hadn't been a dark morning I would never had seen the arc.

If that's only a car ignition coil at whatever voltage it is what could 25Kv do at a far greater distance with more reliable conductors?

 

[snowball]

Much the same thing.

Spark plugs usually require voltage of 12,000–25,000 volts or more to "fire" properly, although it can go up to 45,000 volts

https://en.wikipedia.org/wiki/Spark_plug

 

[broadgage]

He was speaking about the tyres....they do not Earth the vehicle, as rubber is an insulator.

Electric cables used to be insulated with rubber, and some types still are, due to the electrical insulating properties of rubber.

However the rubber used for tyres is rendered slightly conductive by the addition of carbon black during manufacture.
This is done to minimise the build up of static electricity which could result in painful electric shocks to persons exiting the vehicle, and could also be dangerous if petrol was being handled.

As a result, vehicle tyres may only be considered as reasonably insulating at low voltages, up to 1000 volts or so.
At high voltages such as the 25,000 volts used for OHLE, current will pass through the tyres which as a result are liable to get hot enough to burst or catch fire.

 

[gimmea50anyday]

Older cars used to have a black strip with a silver arrow on it hanging down from the back of the car. rarely seen nowadays but it used to earth the car when stationary. Movement of course would lift it off the ground

 

[contrex]

Older cars used to have a black strip with a silver arrow on it hanging down from the back of the car. rarely seen nowadays but it used to earth the car when stationary. Movement of course would lift it off the ground

Those things were bought from accessory shops by gullible people who were persuaded that they prevented car sickness.