Static - acceptable or not?

[peweuk]

Today I used a new power wash for the first time.

When I was finished I removed the plug from the wall socket.
As I went to roll up the cable to put the power washer away I touched the steel pins on the plug and received a hell of a shock.
It wasn't quite the same degree of shock I've experienced from mains cable in the past, but it was certainly greater than the static shocks I've experienced from, for example, the computer.

I rang the supplier who said ' it was probably static so don't worry about it'.

Is that an acceptable response??
Should we expect items such as this to 'routinely' give static shocks.

I must say I don't remember ever having had a static shock from a electrical garden appliance and it did take me a little by surprise - just as well I don't wear a pacemaker

 

[PrenticeBoyofDerry]

I doubt it would be static, more likely some capacitive resistance left in store on the washer.

 

[peweuk]

I doubt it would be static, more likely some capacitive resistance left in store on the washer.

I initially thought that would have been more likely - and if that is the case shouldn't they have some form of warning about this possibly happening????

 

[PrenticeBoyofDerry]

Indeed I would have thought not only a warning but a device to prevent this happening.

 

[plugwash]

Static shocks tend to be very high voltage (often enough to produce blue sparks*) but the total energy is usually very low. Capacitive shocks are lower voltage but much longer duration.

Capacitors are supposed to have drain resistors but they do fail from time to time. I had a 200V shock off the power supply out of a BBC master recently because of a failed drain resistor.

Also some people are just especially sensitive and perceive shocks from voltages/currents that are well within the accepted safety limits.

* As I understand it blue sparks are ionised air while yellow sparks are hot metal. The former usually involve high voltages while the latter involve high currents.

 

[AndyPRK]

You should find yourself a piece of metal to discharge the plug against before reeling it up.


I got so annoyed with static off a king vac I earthed the canister

 

[peweuk]

Thanks guys.

I was a it surprised to receive a call shortly after my last post.
It was from an rep in the service department at the suppliers.
He concluded that perhaps water had made its way inside the pressure washer and 'damaged' the unit such that it was not discharging power properly.
(When I first connected it to the water supply the hose connector split allowing water to spray all over the outside of the unit).

He said it wasn't of great concern , but as it was a fault he would send me out a new body (ie no gun, pipes etc) and to throw away the other one when the replacement arrived.

Very strange response I thought - unless of course it was not an uncommon problem with this particular unit.

I will see how the replacement performs and hopefully the problem will be solved.

 

[AndyPRK]

Yes a bit suspecious. Maybe a known problem.

Anyway that will be useful having a spare unit

 

[peweuk]

Yes a bit suspecious. Maybe a known problem.

Anyway that will be useful having a spare unit

It certainly will.

I bought this one because the last one we had developed a leak in the pump - and as it was 3 years old I could not get any spares to replace the disintegrated rubber sealing ring - typical B&Q, not the cheapest and still have a built in obsolescence.

 

[ban-all-sheds]

typical B&Q, not the cheapest and still have a built in obsolescence.

They may not be the cheapest in terms of retail price, but their buyers scour the world for the cheapest nastiest tat they can find.

and as it was 3 years old I could not get any spares to replace the disintegrated rubber sealing ring

And they DGAS about spares and after-sales service.

 

[PrenticeBoyofDerry]

Anyway that will be useful having a spare unit

Especially when the missus wants to do a bit of deep cleaning, just let her find out about the belt of electricity expected by her own accord!

 

[Lectrician]

My laptop charger does this too. It is stored capacitance, which should be drained internally, but has failed.

 

[JohnW2]

My laptop charger does this too. It is stored capacitance, which should be drained internally, but has failed.

One does hear such reports. I have to say that I'm surprised that they use capacitors which are 'that good' in such items. Given the relatively low capacitances involved, I would have expected the internal leakage of most cheapo capacitors to be enough to fairly rapidly 'auto-discharge' it!

Kind Regards, John

 

[Monkeh]

My laptop charger does this too. It is stored capacitance, which should be drained internally, but has failed.

One does hear such reports. I have to say that I'm surprised that they use capacitors which are 'that good' in such items. Given the relatively low capacitances involved, I would have expected the internal leakage of most cheapo capacitors to be enough to fairly rapidly 'auto-discharge' it!

Kind Regards, John

They do, and usually have bleed resistors, but it still takes a few seconds. Any faster and it's energy wasted and heat generated in operation. I've been on the receiving ends of such belts myself.

 

[JohnW2]

They do, and usually have bleed resistors, but it still takes a few seconds. Any faster and it's energy wasted and heat generated in operation. I've been on the receiving ends of such belts myself.

So have I Of course, it's pot luck as to what part of the cycle one is at when power is removed, so a significant shock is not inevitable, even 'immediately' after disconnection (and even if there is no bleed resistor).

You seem to be almost suggesting that the 'problem' is insoluble, in as much as a bleed resistor of low enough resistance to achieve very rapid discharge would be 'unacceptable' during normal operation. I suspect that some people (who don't like any shocks!) might disagree. I'm not sure what sort of capacitances we're talking about, but if it were, say, 0.1 μF, then a bleed resistor of 1 MΩ would essentially discharge it in well under half a second, and the 'wasted power' during operation would amount to only about 53 mW.

Kind Regards, John