Electrical Safety - Very Important Note.

[Crossy]

Ethanol, never tried that, what do you use as a mixer?

Ethanol (as I'm sure you know but others may not) is the active ingredient in all alcoholic beverages.

[impulse]

Actually ethanol is a very poor conductor about 0.0013 uS/cm whereas isopropyl alcohol is a reasonable conductor at 3.5 uS/cm (so the type of alcohol is important).

If you're drinking isopropyl alcohol in the pool, getting an electric shock is not high on your list of worries.

Love your posts, you have probably saved a half dozen lives if your E^- advice is followed..

Edited March 31, 2013 by impulse

[xylophone]

Fridges and freezers tend to be 'leaky' and if you have the RCD on lowest setting (5mA ??) it may occasionally trip. Also a lightning strike somewhere near can cause ours to trip if on too low a setting.

Electric cookers and hotplates are also notoriously "leaky".

[NanLaew]

I am renting a house that has an RCD installed; there's a red indicator lamp showing it has power. All the power outlets in the house are 2-pin and there's nary a ground wire running anywhere. I have looked.

Every so often, the RCD will trip at it's lowest sensitivity settings, killing all power.

Why?

An appliance somewhere has an earth leak, or perhaps you have a dodgy joint somewhere that's got damp. Could be any of a myriad of reasons.

When you say 'lowest sensitivity' do you mean 5mA or 30mA? If it's set to 5mA it could just be your computer (they do tend to be leaky due to the mains inlet filter), try winding your RCD up a notch and see if the problem goes away, just don't take it above 30mA.

How can two-pin appliances have an earth leak?

There's only 2-pin power outlets on the walls and 2-pin plugs on the appliances. There are no ground wires anywhere in the house and there's no ground-spike either.

[Tywais]

I am renting a house that has an RCD installed; there's a red indicator lamp showing it has power. All the power outlets in the house are 2-pin and there's nary a ground wire running anywhere. I have looked.

Every so often, the RCD will trip at it's lowest sensitivity settings, killing all power.

Why?

An appliance somewhere has an earth leak, or perhaps you have a dodgy joint somewhere that's got damp. Could be any of a myriad of reasons.

When you say 'lowest sensitivity' do you mean 5mA or 30mA? If it's set to 5mA it could just be your computer (they do tend to be leaky due to the mains inlet filter), try winding your RCD up a notch and see if the problem goes away, just don't take it above 30mA.

How can two-pin appliances have an earth leak?

There's only 2-pin power outlets on the walls and 2-pin plugs on the appliances. There are no ground wires anywhere in the house and there's no ground-spike either.

Concrete, especially the bottom floor, is partially conductive to the earth due to moisture retention in the concrete. This will supply a leakage path to an appliance. Common complaint on here are PCs that members get a light shock from that don't have a ground pin. The voltage is coming from the PC filter which is connected at the center point of the filter to the case of the PC. Standing on concrete/ceramic/etc. floors gives a path from the feet to the case.

[jocko]

Alcohol is a poor electrical conductor.

No it isn't, that is just the sort of shoddy advice I have come to expect from this forum, you should ashamed of yourself.....

Not sure what you are on about but pure alcohol is non-electrolytic (no ion carriers) and as such is a poor conductor. Specifically its conductivity, depending on which alcohol type, is 6 uS/M which is 16 Mohms-Meters. However, any additional components to it can increase conductivity such as hops. Guess you think pure water conducts electricity well also.

Is Ethanol Conductive Electrically?

In truth, ethanol, like other alcohols, conducts electricity rather poorly because it is a non-electrolyde. Ethanol itself contains practically no electrolytes besides those that form as an effect of auto-ionization; these electrolytes, however, are in so small a number that they’re virtually negligible.

Ethanol is also called a covalent compound because it does not contain ions that are necessary for electricity to be able to flow through a liquid or a solution. This means that electrical charge cannot be carried completely through ethanol. In sum, ethanol cannot conduct electricity.Alternative Energy - Ethanol

But we digress.

Ethanol, never tried that, what do you use as a mixer?

There used to be a drink called aftershock don't know the recipes but it put me on my back a few times.

[Crossy]

There used to be a drink called aftershock don't know the recipes but it put me on my back a few times.

Still available, 14 Quid in Tesco UK http://www.mysupermarket.co.uk/tesco-price-comparison/spirits/aftershock_red_cinnamon_liqueur_500ml.html

[jocko]

There used to be a drink called aftershock don't know the recipes but it put me on my back a few times.Still available, 14 Quid in Tesco UK http://www.mysupermarket.co.uk/tesco-price-comparison/spirits/aftershock_red_cinnamon_liqueur_500ml.html

Any person who has that info should never give advice about electricity.

No way

[NanLaew]

I am renting a house that has an RCD installed; there's a red indicator lamp showing it has power. All the power outlets in the house are 2-pin and there's nary a ground wire running anywhere. I have looked.

Every so often, the RCD will trip at it's lowest sensitivity settings, killing all power.

Why?

An appliance somewhere has an earth leak, or perhaps you have a dodgy joint somewhere that's got damp. Could be any of a myriad of reasons.

When you say 'lowest sensitivity' do you mean 5mA or 30mA? If it's set to 5mA it could just be your computer (they do tend to be leaky due to the mains inlet filter), try winding your RCD up a notch and see if the problem goes away, just don't take it above 30mA.

How can two-pin appliances have an earth leak?

There's only 2-pin power outlets on the walls and 2-pin plugs on the appliances. There are no ground wires anywhere in the house and there's no ground-spike either.

Concrete, especially the bottom floor, is partially conductive to the earth due to moisture retention in the concrete. This will supply a leakage path to an appliance. Common complaint on here are PCs that members get a light shock from that don't have a ground pin. The voltage is coming from the PC filter which is connected at the center point of the filter to the case of the PC. Standing on concrete/ceramic/etc. floors gives a path from the feet to the case.

That's all pretty logical and I buy that.

However, in the case of the house I am renting that has absolutely no earth wiring or spike anywhere, what is the RCD connected to? What is it's reference for this 'leakage' tripping?

Maybe I need to read up on RCD installations but pretty sure that it has something to do with having an actual earth ground connection to be really functional no?

[Crossy]

Maybe I need to read up on RCD installations but pretty sure that it has something to do with having an actual earth ground connection to be really functional no?

Nope, an RCD does NOT need a ground reference to function.

Put simply it measures the current in the live cable and the current in the neutral cable. If they are the same it does nothing, if they are different by more than a set amount (30mA) it assumes (reasonably) that the difference is caused by an earth fault and opens the circuit.

That is why the beasts are sometimes called 'Differential Circuit Breakers'. The term RCD means 'Residual Current Device' the residual current being that difference between L and N.

[Forkinhades]

The RCD will still work without an earth, a 30 mA RCD will still work
even if the earth impedance (which could be your concrete walls) is as
high as 1667 ohms. There are many threads on this in TV.

In the UK when a TT system is installed (most common in Thailand) It is MANDATORY to install an earth rod, and the impdance should be measured, anything below 20 ohms is acceptable, but the lower the better. BS7671
states that a earth rod (TT system) that has a value higher than 200 ohms is considered unstable

[xylophone]

Maybe I need to read up on RCD installations but pretty sure that it has something to do with having an actual earth ground connection to be really functional no?

Nope, an RCD does NOT need a ground reference to function.

Put simply it measures the current in the live cable and the current in the neutral cable. If they are the same it does nothing, if they are different by more than a set amount (30mA) it assumes (reasonably) that the difference is caused by an earth fault and opens the circuit.

That is why the beasts are sometimes called 'Differential Circuit Breakers'. The term RCD means 'Residual Current Device' the residual current being that difference between L and N.

As I recall from my apprenticeship they work with what used to be called a core balance transformer?? Am I right? Edited April 2, 2013 by xylophone

[Tywais]

As I recall from my apprenticeship they work with what used to be called a core balance transformer?? Am I right?

If you look at my previous post #10 I have a diagram of it - http://www.thaivisa.com/forum/topic/629771-electrical-safety-very-important-note/#entry6256407

So yes, a balanced core would be accurate.

[SantiSuk]

Duplicate

Edited April 8, 2013 by SantiSuk

[SantiSuk]

You are absolutely right, you must take extra precautions with electric in swimming pools.

TAT Poster

"Welcome to Thailand. Your safety is our biggest concern"

[Chaichara]

It's a staggering thought, but I have seen many 'professional' pools where none of the electrical equipment is earthed at all. RCCBs are also available as DIn rail modules.