USB charger outlet in Bathroom Zone2

Peter69 said:

I've been asked to add a USB charging port into a bedroom with a bath in it.

mapj1 said:

It must be said, very few modern bathrooms have that much free space

gkenyon said:

electrocution in the bath

I suppose that in the days before fixed plumbing, one might have taken a bath in a bedroom, but my mind boggles nowadays. Who is going to spend so long in a bath that the 'phone's battery will run out? 

Presumably, there would already be sockets in the bedroom.

I am bound to wonder what completed the circuit in Graham's link. Could it be that supplementary bonding contributed?

gkenyon said:

Connections to Earth (or bonding) aside, when someone is immersed, current thinking is that there isn't an agreed limit of voltage below which things can be considered "safe" - so the device itself might be bad enough in some cases ... but that is not clear.

It makes you wonder how they can put the electrode right inside the heart (for ablation purposes) and get away with it.

The interested may find 

https://www.researchgate.net/profile/G-Cargill-Iii/publication/335250921_Electric_Shock_Drowning_Causes_and_Prevention/links/5d5b416b45851521025227f1/Electric-Shock-Drowning-Causes-and-Prevention.pdf 

informative. The problem is current in the body, and that in turn depends a lot what sort of wet - fresh water, tap water and sea water are very different terms of currents in the body, and the 2 cases,

1) where a body is part immersed in water that is one of the 2 contacts, where low resistance water as a series element makes it worse,

2) Where the body is  fully immersed in water carrying a current to and from elsewhere, and it might be better if the liquid was a lower resistance parallel path to reduce the current through the body.

In practice voltages as low as 28 have been reported as lethal but the circumstances that achieved that have been very unlucky coincidences of all the unfortunate factors.

The most reliable safety measure is to have current and time limiting, rather than voltage, which is where RCDs have an advantage.

Mike.

Other factors include:

 - Skin resistance when substantially immersed is unknown ... and may drop to very low (nearly zero) values. This factor means that very low voltages, perhaps into single figures, might actually be very bad to someone who is substantially immersed in a bath.

 - the passage of electricity through water is complicated by the fact we are looking at electric fields emanating from the 'electrodes' in the water, and the passage of current is through the path of least resistance ... which might not be where you think it is because of things like concentration of salts increasing near the body, and also the points of entry/exit to tbe body seem to concentrate around the lowest impedance path through it ... usually the chest/trunk, where they can cause a lot of damage.

 - in electric shock drowning, the direction of current flow without the person in the water comes into play, due to the distances involved.

gkenyon said:

Skin resistance when substantially immersed is unknown ... and may drop to very low (nearly zero) values. This factor means that very low voltages, perhaps into single figures, might actually be very bad to someone who is substantially immersed in a bath.

I assume that most of us have licked a PP3 battery  so it cannot just be voltage.

If 30 mA is the safe limit, 9 V across 300 Ω could be risky.

Worth noting my cardiologist doesnt recommend this as teeth have a nerve pathway to the heart and pp3 have cause arrhythmia.

Frequency voltage/ current and time, all finely tuned. The bodies nerve do not react to higher frequencies and the 'burn' is the desired result. There are no pain receptors in the heart but it does make you cough?

Chris Pearson The pathway is important here. As others have pointed out, there are routes to severe damage ... but not, in otherwise healthy people, the heart.

Peter69 said:

There are no pain receptors in the heart

Clearly, you haven't had an awake cardiac ablation procedure; and surely, it is common knowledge that a myocardial infarction (heart attack) can be very painful.

I have had several and countless biopsies. Over 100 cardiac inversions or jump starts as I call them, most awake - the external ones really hurt the internal ones dont.

The only sensation I or others I deal with feel is the catheter moving around.

In the 'good contact', wet body case, the sort of [low] limits used in agricultural areas may be more relevant (think of licking the brass / steel nails in a lemon test..).

Quite a different consideration compared to the dehumidifier in the laundry-bathroom scenario .

In the 'good contact', wet body case, the sort of [low] limits used in agricultural areas may be more relevant (think of licking the brass / steel nails in a lemon test..).

Quite a different consideration compared to the dehumidifier in the laundry-bathroom scenario .