I get a shock from a single phase ac capacitor I want to ask about!

[Tony Stewart]

The major conduction factor in concrete, as I recall from my factory ESD implementation days is whether the concrete has a good moisture barrier underneath. Most do not and so are excellent for ESD prevention but poor for HV isolation.
So moist concrete ends up being much worse than dry wood. Wood in fact if dry with oil is the primary cellulose insulation in HV transformers. moisture content and its absorption factor being the key factor of any dielectric insulation.

BTW All insulators are dielectrics .

... and water has a high relative permittivity of >60 as well as ionized conducting salts if contaminated and transformer insulating oil is low 2-4 with better H2O inhibitors.

 

[Tony Stewart]

Alternating current can pass through a capacitor, so can definitely give you a shock. A 1.7uF cap has an impedance of ~ 1.9k at 50Hz, so can allow ~ 220/1.9k = 115mA (rms) to flow. That is more than enough to kill you!

Fortunately your finger tip impedance is typically 100kΩ give or take 1 decade if dry or wet which limits the current initially to 1% of this, but ionization occurs at the surface, can drop another order of magnitude.

250uA is allowed in Y-rated cap leakage in line filters of power supplies and is considered safe but well above perception thresholds.

More effects are felt going thru the body than between arm and finger, so one hand in pocket is the Old Tv repairmans rule when poking around discharged flyback caps or voltage doublers etc...

 

[Tony Stewart]

No

thanks for your replies

it has 1.7 uf and i was stand on wood I feel pain on arm

note the motor was disconnected and no current or voltage across else capacitor charge
does wood is good for resistance
its loocks like tha

is it very dangerous and i should go to doctor?

and for more safety standing on floor or wood is better?

, but you might know what acupuncture does for strong healing. Dont push your luck.

 

[audioguru]

Your arm got a shock and maybe the dead arm will soon fall off.

 

[Mido2115]

really good info thanks for your useful replies

i will take care

 

[PLC Nut]

A general guideline for receiving an electric shock is to go to the hospital and get your hart checked. You can die days, weeks or months after receiving a shock. Just keep that in mind

Also wood is not a good insulator at all. That is why any rescue kit for people receiving electric shocks do not contain hooks that are made of wood. The hooks have to be tested regularly to ensure their insulation resistance has not fallen.