Static electricity

[Janey72]

Hello :))

I have recently experienced static electricity onboard for the first time, from the radio, the stove, a metal chair - any thoughts? Thanks a million PS I did do some searching on the forum but did not spot anything...:)

[Tony Brooks]

Sorry if this gets interpreted as sexist, its not meant to be. Any new clothes, underwear, carpets made form synthetic fibre. It is known you can build up static on yorself in such materials.

[Janey72]

I understand that - but nothing has changed in that regard - thanks

I dont even have new slippers...

Floors are wooden

And I dont tend to wear synthetic fabrics...

[system 4-50]

The humidity is relevant.

[Tracy D'arth]

• Are you on a mains hook-up?  If so do investigate your earthing arrangement.

[sharpness]

In a previous life I worked in different offices over many years. In cold dry spells in winter I very often used to get quite painful static shocks from metal filing cabinets. One winter it got so bad that we had someone in to water the synthetic carpet tiles with a watering can of something. Others used to have similar problems to a lesser extent, others not at all. I've never had the same problem on the boat, if you are on a shoreline I'd say get your electrics checked by a professional.

[Onewheeler]

The inside of your boat is probably much warmer than the outside. The moisture content of the cold external air is low (even if the external relative humidity is high). If you're not putting much moisture into the inside of the boat from breathing, sweating or cooking the RH will be low, which is good for generating static.

[Jen-in-Wellies]

13 hours ago, Onewheeler said:

The inside of your boat is probably much warmer than the outside. The moisture content of the cold external air is low (even if the external relative humidity is high). If you're not putting much moisture into the inside of the boat from breathing, sweating or cooking the RH will be low, which is good for generating static.

According to the Met Office RH is 50% in Leighton Buzzard at 0C today. An on line calculator reckons that is 13.5% at a cosy boat cabin temperature of 21C. Plenty low enough to allow static charges to build up and zap you.

Jen

[Chewbacka]

Usually it’s you that builds up the charge and you get a shock when you discharge yourself to ground.  In the electronics industry we used to have conductive straps from inside your shoe to under the sole as shoes are often good insulators and the strap limits the voltage you can charge up to.

 

Try walking around in bare feet for a day or two to see if the problem goes away.

[ditchcrawler]

I would like to know a bit more about what you were touching to receive these static shocks?

[Tony Brooks]

1 minute ago, ditchcrawler said:

I would like to know a bit more about what you were touching to receive these static shocks?

Form the OP:-   from the radio, the stove, a metal chair

 

If its is as I suspect a charge build up on the person I can understand the stove and radio but I am not sure how the chair can transmit charge.

[ditchcrawler]

2 minutes ago, Tony Brooks said:

Form the OP:-   from the radio, the stove, a metal chair

 

If its is as I suspect a charge build up on the person I can understand the stove and radio but I am not sure how the chair can transmit charge.

And if anything else was being touched at the same time

[Bee]

Used to lay out big Dacron sails on a loft floor and sweep them to get them flat. Didn't half get some shocks off the tea machine sometimes.

[Chewbacka]

On 31/12/2020 at 15:55, Tony Brooks said:

Form the OP:-   from the radio, the stove, a metal chair

 

If its is as I suspect a charge build up on the person I can understand the stove and radio but I am not sure how the chair can transmit charge.

Because a metal chair on a non insulating floor (a solid wood floor depending upon humidity will have sufficient moisture content to be electrically leaky) will dissipate a high voltage static charge which ‘you’ have built up moving about.  You need electrically ‘leaky’ shoes to prevent this.

[David Mack]

On 31/12/2020 at 14:05, Chewbacka said:

 

Try walking around in bare feet for a day or two to see if the problem goes away.

 

At this time of year?

[Chewbacka]

1 hour ago, David Mack said:

 

At this time of year?

Well if I was stood in the middle of the boat floor I would not touch the end of a live mains cable in the hope I don’t get a shock as the humidity is low. That’s only 240v not many thousand like static charges.  So yep, even in this weather your wooden boat floor is not a good enough insulator.

[Tacet]

32 minutes ago, Chewbacka said:

Well if I was stood in the middle of the boat floor I would not touch the end of a live mains cable in the hope I don’t get a shock as the humidity is low. That’s only 240v not many thousand like static charges.  So yep, even in this weather your wooden boat floor is not a good enough insulator.

Does this mean you must find a low-humidity broom before shoving an electrically shocked victim away from the source? 

[TheBiscuits]

5 minutes ago, Tacet said:

Does this mean you must find a low-humidity broom before shoving an electrically shocked victim away from the source? 

 

I'm pretty sure the first aid advice includes standing on a good insulator (newspapers/ rubber mat / whatever) as well as using a broom to break contact between the patient and the electricity supply.

 

 

[Chewbacka]

27 minutes ago, Tacet said:

Does this mean you must find a low-humidity broom before shoving an electrically shocked victim away from the source? 

The broom handle is like an inch or so diameter and 4 or so feet long, so fairly safe, whereas a floor contact area is foot sized (maybe 45 square inches) and 3/4 of an inch thick, so much lower resistance.  That said, I would not use a wet broom.

[cuthound]

19 hours ago, Chewbacka said:

Because a metal chair on a non insulating floor (a solid wood floor depending upon humidity will have sufficient moisture content to be electrically leaky) will dissipate a high voltage static charge which ‘you’ have built up moving about.  You need electrically ‘leaky’ shoes to prevent this.

 

Indeed  that is how the antistatic straps you use when handling delicate circuit boards work. They alkow the static buildvup to leak away rather thsn discharge suddenly (and painfully).

 

Data Centres control the humidity by using humidifiers on humidity stats to control humidity. In effect they are large electric kettles and increase humidity by adding water vapour to the air within the room.

 

The OP could raise the humidity by either boiling a kettle or using a garden sprayer to add cold moisture to the air.

Edited January 3, 2021 by cuthound

[ditchcrawler]

1 hour ago, cuthound said:

 

 

 

The OP could raise the humidity by either boiling a kettle or using a garden sprayer to add cold moisture to the air.

And the rest of the boaters are trying to get rid of humidity. Seems you can never keep boaters happy ??️