Electrical Safety - Very Important Note.

[AllanB]

Without doubt the most important component in a swimming pool system is the RCD, as this is the primary life protecting device and since you have the two worst bed-fellows together, water and electricity, no pool should be installed without one The one use here in Thailand is called a "Safety Cut" and a recent call from a customer has cast doubt on whether they actually work.

This guy told me he recently had a fire in his house when a ceiling light shorted out, impossible if the RCD was effective, what made things worse was that the roof insulation was not fire retardant, so his entire roof cavity caught fire. He then replaced this unit and found that the new one didn't work either, I then popped round to my neighbour's house and his didn't work either.

In the UK, I work closely with fire brigades, now called "fire and rescue services" and for good reason, they now spend much less of their time putting out fires, compared to years ago. One of the main reasons for this is the mandatory fitting of RCD consumer units, so in the UK they do work, stop fires and save lives, though mainly through shock prevention.

In contrast my new house here didn't even have an earth rod installed and certainly no RCD, so two nice death trap electric showers. Look around you and see the state of the electrics in Thailand, it is third world standard at best.

So when we built our pool we used a UK built unit and would advise everyone else to do the same, I guess the Ausi ones should be the same, but the US work on 110v so are unsuitable..

Edited March 31, 2013 by AllanB

[lopburi3]

A fire can start from shorting between neutral/hot cable wires with no ground fault so RCD will not prevent such a fire. Have had it happen due to rats eating wire insulation. Best to make sure breakers are not over-rated as well as having RCD protection.

[Crossy]

Correct ^^^, an RCD (even a UK one) does NOT necessarily provide protection from an arcing connection unless that arc is to ground.

The US have a device they call an AFCI (Arc Fault Circuit Interrupter) which does detect arcs and turns off the power in much the same way as an RCD (or GFCI in the US) does for ground faults.

I've never seen a 220V AFCI.

The OP is of course totally correct in stating that you must have an RCD to protect your installation.

[AllanB]

A fire can start from shorting between neutral/hot cable wires with no ground fault so RCD will not prevent such a fire. Have had it happen due to rats eating wire insulation. Best to make sure breakers are not over-rated as well as having RCD protection.

This is not so, any short detected, (in excess of 5 miiliamps for more than 25 microseconds) regardless of whether it is live or neutral, will trip a properly functioning RCD, that is the whole point of them, even a blown light bulb can cause a trip, which can be a pain,

Since their introduction in the UK, fires due to electric faults have virtually disappeared, except on older properties without them. The arsonists job has really become difficult and even James Bond has had to find other methods of killing the bad guys.

If I buy an old house in the UK, the first thing I do is upgrade to an RDC board and I keep an RCD adapter in my tool kit at all times for use with power tools on unknown mains supplies.

Not for me a pair of crocodile clips on overhead cables..

If a circuit-breaker is overloaded it will trip out anyway.

[AllanB]

Correct ^^^, an RCD (even a UK one) does NOT necessarily provide protection from an arcing connection unless that arc is to ground.

The US have a device they call an AFCI (Arc Fault Circuit Interrupter) which does detect arcs and turns off the power in much the same way as an RCD (or GFCI in the US) does for ground faults.

I've never seen a 220V AFCI.

The OP is of course totally correct in stating that you must have an RCD to protect your installation.

Edited March 31, 2013 by AllanB

[Crossy]

Correct ^^^, an RCD (even a UK one) does NOT necessarily provide protection from an arcing connection unless that arc is to ground.

The US have a device they call an AFCI (Arc Fault Circuit Interrupter) which does detect arcs and turns off the power in much the same way as an RCD (or GFCI in the US) does for ground faults.

I've never seen a 220V AFCI.

The OP is of course totally correct in stating that you must have an RCD to protect your installation.

How can you have an arcing connection, if not to earth or a short between L and N?

A L-N arc/short will NOT be detected by an RCD which operates by measuring the difference between the L and N currents. L-E and (to a lesser extent) N-E arcs/leaks will be detected if they carry more then the trip current of the RCD.

A dodgy twisted connection will arc on load and has no path L-N or L-E which is likely why your mate's arcing ceiling rose didn't trip his RCD.

A L-N short will, of course, take out the over current protection which may be built in to the RCD (making it an RCBO).

[Crossy]

This is not so, any short detected, (in excess of 5 miiliamps for more than 25 microseconds) regardless of whether it is live or neutral, will trip a properly functioning RCD, that is the whole point of them, even a blown light bulb can cause a trip, which can be a pain,

NOPE!

The normal RCD installed in UK domestic environments is 30mA trip, the requirements are that it trips at between 15 and 30mA. It must NOT trip at <15mA, it MUST trip at >30mA.

BS7671 (16^th edition, I don't have a 17^th but see no reason why it should be different) regulation 713-13-01 states that to comply with BS 7071 (BS7288 for RCD outlets) that the RCD must trip within 200ms at I_n (30mA) and 40ms at I_n x 5 (150mA). I_n being the rated trip current (differential between the L and N currents).

To be honest, it does not matter exactly what it is protecting you against (primarily electric shock), you should have RCD protection on all circuits.

[AllanB]

Correct ^^^, an RCD (even a UK one) does NOT necessarily provide protection from an arcing connection unless that arc is to ground.

The US have a device they call an AFCI (Arc Fault Circuit Interrupter) which does detect arcs and turns off the power in much the same way as an RCD (or GFCI in the US) does for ground faults.

I've never seen a 220V AFCI.

The OP is of course totally correct in stating that you must have an RCD to protect your installation.

How can you have an arcing connection, if not to earth or a short between L and N?

A L-N arc/short will NOT be detected by an RCD which operates by measuring the difference between the L and N currents. L-E and (to a lesser extent) N-E arcs/leaks will be detected if they carry more then the trip current of the RCD.

A dodgy twisted connection will arc on load and has no path L-N or L-E which is likely why your mate's arcing ceiling rose didn't trip his RCD.

A L-N short will, of course, take out the over current protection which may be built in to the RCD (making it an RCBO).

Thanks, I learnt something that I should be looking for an RCBO.

http://www.ebay.co.uk/itm/2-WAY-GARAGE-CONSUMER-UNIT-45AMP-MAIN-SWITCH-WITH-16AMP-RCBO-6AMP-MCB-/130871131988?pt=UK_BOI_Materials_Supplies_Electrical_ET&hash=item1e7886ff54

Does the RCBO only function on the 16 amp output, as it shows the 6 amp as being an MCB?

Edited March 31, 2013 by AllanB

[Crossy]

Thanks, I learnt something that I should be looking for an RCBO.

Not always easy to find in Thailand although they're getting more common.

We actually have front end RCDs in each of our two consumer units as RCBOs were not available when we wired our home. Separate over-current protection is provided by MCBs on each circuit.

A big issue with local sparkies is that they will pick up any old neutral when installing a new circuit, this confuses the he** out of RCBOs

EDIT Your garage CU has a 16A RCBO which protects ONLY the 16A power outlet circuit. As it's intended for a garage where wiring would be surface mounted there is not a requirement for RCD protection of the lighting circuit. BS7671 requires RCD protection on all circuits where wiring is <50mm below the surface of a wall but not if it's surface mounted (and therefore visible).

The primary purpose of the RCBO in this instance is to protect you from shock when you chop the lawnmower cable.

[Tywais]

As mentioned, an RCD will not protect against a L-N arc/short. RCD works based on the differential current between L-N which should be balanced, that is current equal in both legs. Any extra current detected due to an alternate path to earth/ground will misbalance the differential currents.

[AllanB]

Thanks, I learnt something that I should be looking for an RCBO.

Not always easy to find in Thailand although they're getting more common.

We actually have front end RCDs in each of our two consumer units as RCBOs were not available when we wired our home. Separate over-current protection is provided by MCBs on each circuit.

A big issue with local sparkies is that they will pick up any old neutral when installing a new circuit, this confuses the he** out of RCBOs

EDIT Your garage CU has a 16A RCBO which protects ONLY the 16A power outlet circuit. As it's intended for a garage where wiring would be surface mounted there is not a requirement for RCD protection of the lighting circuit. BS7671 requires RCD protection on all circuits where wiring is <50mm below the surface of a wall but not if it's surface mounted (and therefore visible).

The primary purpose of the RCBO in this instance is to protect you from shock when you chop the lawnmower cable.

This is the problem in Thailand, the sheer lack of expertise in all fields, if you want any, for example, plumbing work carried out you have to watch them or they will knock your bloody house down putting a pipe in. The same is true of electrical work, the sparks I have met know virtually nothing and whilst I am not allowed to carry out any of this work myself, I need the knowledge so I can get the "qualified man" to do it correctly.

That makes this particular topic and the information imparted, very useful. so thanks again Cossy....

I know three people here who have suffered serious injuries due to electric faults, one woman lost both her arms. Others I don't know about are the dead ones.

One thing..........., if an RCD cannot detect arc faults, why does a blown light bulb trip them out?

.

Edited March 31, 2013 by AllanB

[Crossy]

One thing..........., if an RCD cannot detect arc faults, why does a blown light bulb trip them out?

When an incandescent lamp fails with a bang it's invariably because during its failure it goes short-circuit.

Of course this will take out an over-current device, so if you have an RCBO it's likely the over-current element that trips.

However, I have seen plain RCDs without over-current sensors trip on the same fault. Personally I believe that it's caused by the massive current saturating the sense toroid and causing the mechanism to release, maybe that's actually why the RCBO trips.

Others may have a better explanation.

[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?

[Crossy]

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.

[ThaidDown]

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.

[jbrain]

Why would one need an RCBO when an RCCB together with MCB's has the same function ? At least that's what I understand from the ABB website,

Edited March 31, 2013 by jbrain

[Satcommlee]

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

[AllanB]

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.

You have now become our official resident electrical consultant ​, so you could be here for some time. But thanks, this swimming pool forum desperately needs some really knowledgeable people.

Post your phone number and we can all call you direct...... ..........day or night.

[AllanB]

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

Looks good, I have a spare extension lead. I think the beer is the key ingredient here, it makes you safe from a ll potential dangers.

[Tywais]

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

Looks good, I have a spare extension lead. I think the beer is the key ingredient here, it makes you safe from a ll potential dangers.

Alcohol is a poor electrical conductor.

[Crossy]

Why would one need an RCBO when an RCCB together with MCB's has the same function ? At least that's what I understand from the ABB website,

There is absolutely nothing to stop you configuring your DB with all RCBOs, except cost.

Using a front end RCD with a bunch of regular MCBs will provide equivalent protection from shock at a much lower cost but with the added inconvenience of an RCD trip taking out all the circuits.

The usual cost trade off is to put sensitive kit (like your freezer) on an RCBO and the rest of the circuits on an RCD with MCBs so something else leaking won't kill your food.

[Forkinhades]

Why would one need an RCBO when an RCCB together with MCB's has the same function ? At least that's what I understand from the ABB website,

RCBO will only turn off that circuit, whereas an RCD will turn everything off. Annoying if you get get nuisance tripping

[Forkinhades]

^ crossy posted 1 second before!

[Forkinhades]

wonders where Electau is....................

[Crossy]

You have now become our official resident electrical consultant ​, so you could be here for some time. But thanks, this swimming pool forum desperately needs some really knowledgeable people.

Post your phone number and we can all call you direct...... ..........day or night.

Electrical stuff usually ends up in DIY, swimming pools tends to talk about pH balance and free chlorine, things I know sod all about (our 'pool' has fish in it and they like the algae).

Nothing to stop members PMing me any time but posting on the forum is the better solution, more get to see it

[AllanB]

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

Looks good, I have a spare extension lead. I think the beer is the key ingredient here, it makes you safe from a ll potential dangers.

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.....

[Forkinhades]

It is also very important to check the operation of these devices with the right equipment by a professional.

[Tywais]

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.

[Crossy]

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).

Pure water is also a poor conductor at 0.04 uS/cm but add them together and you get something else:

100 proof gin is about 10 uS/cm and NYC water is 72 uS/cm so it's evident that adding impurities (does anyone drink NYC water?) does increase conductivity significantly.

Source http://www.smartmeasurement.com/en/wizards/flowmeter/flmtr_mag_conductivity.asp

[AllanB]

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?