Shower with no RCD or supplementary bonding

MrJack96: 
 

So just to clear this up a shower with no RCD and supplementary bonding is safe until we then have a fault which could end up letting water in. This could the track across to us then we end up touching an earthed pipe for example? 

well unless the shower had exposed metal bits itself and there was a failure mode where they came live somehow, then, yes. 

And quite a lot of cubicle designs do not have solidly earthed pipes or door frames to complete the path.

Note that even with a leak, assuming it is the incoming clean water, the column of water connecting victim to the live parts needs to be quite short and fat - in the sense of the cross -section of the water path being a some few square cm, and the path length being not too many cm long.   Otherwise it is just a liquid filled resistor and keeps the current down to ‘tingle’ rather than ‘lethal’ levels.

A thin thread of water few mm in diameter and  several cm long will not do.

Mike

PS units of water purity… 

TDS (mg/L) = k · EC (µS/cm)

Total dissolved solids in milligrams /litre  =how much salty residue stuff (in milligrams) is left behind if you boiled off a litre of water .

k varies a bit but for typical calcium and sodium sized impurities that are singly or double ionized per atom (this relates to how many electrons drop off the ions when they get wet )is between 0.5 and 1.

Electrical Conductivity  in µS/cm is 1 over the resistance of a one cm cube of water in megohms.

Tap water around the world typically has conductivity values ranging from 50 (pure) to 1500 µmho/cm (becoming undrinkable, or at least seriously unpleasant to drink, this upper limit represents around 1 gram or so of salts per litre.)

so 1/50 of a megohm = 20k ohm per cm cubed to more like 1/1500 of a megohm = 700 ohms per cm cube.

If we pretend  that 15mm plastic pipe has an interior cross-section of 1square cm, and I appreciate its not quite,  then a foot of that pipe (30cm) could be (20k*30) = 600k if the local tap water is very pure, or more like (0.7k* 30) , 21 k or so. for the crummy stuff.   Even the latter would give a  ~ 12mA shock from 230V mains, which is not likely to either trip an RCD or kill you. It is quite likely to explore your full vocabulary of disappointment however. ?

MrJack96: 
 

So just to clear this up a shower with no RCD and supplementary bonding is safe until we then have a fault which could end up letting water in. This could the track across to us then we end up touching an earthed pipe for example? 

well unless the shower had exposed metal bits itself and there was a failure mode where they came live somehow, then, yes. 

And quite a lot of cubicle designs do not have solidly earthed pipes or door frames to complete the path.

Note that even with a leak, assuming it is the incoming clean water, the column of water connecting victim to the live parts needs to be quite short and fat - in the sense of the cross -section of the water path being a some few square cm, and the path length being not too many cm long.   Otherwise it is just a liquid filled resistor and keeps the current down to ‘tingle’ rather than ‘lethal’ levels.

A thin thread of water few mm in diameter and  several cm long will not do.

Mike

PS units of water purity… 

TDS (mg/L) = k · EC (µS/cm)

Total dissolved solids in milligrams /litre  =how much salty residue stuff (in milligrams) is left behind if you boiled off a litre of water .

k varies a bit but for typical calcium and sodium sized impurities that are singly or double ionized per atom (this relates to how many electrons drop off the ions when they get wet )is between 0.5 and 1.

Electrical Conductivity  in µS/cm is 1 over the resistance of a one cm cube of water in megohms.

Tap water around the world typically has conductivity values ranging from 50 (pure) to 1500 µmho/cm (becoming undrinkable, or at least seriously unpleasant to drink, this upper limit represents around 1 gram or so of salts per litre.)

so 1/50 of a megohm = 20k ohm per cm cubed to more like 1/1500 of a megohm = 700 ohms per cm cube.

If we pretend  that 15mm plastic pipe has an interior cross-section of 1square cm, and I appreciate its not quite,  then a foot of that pipe (30cm) could be (20k*30) = 600k if the local tap water is very pure, or more like (0.7k* 30) , 21 k or so. for the crummy stuff.   Even the latter would give a  ~ 12mA shock from 230V mains, which is not likely to either trip an RCD or kill you. It is quite likely to explore your full vocabulary of disappointment however. ?