Electrifying sensation whilst soldering with ESD wrist strap

[electroguy]

An RCD has no connection to earth and an RCBO only a functional (not protective, and not part of the final circuit) earth. An ELCB is an old, and often dangerous device which is unsafe to continue using in most cases.

Thank you, the words i was looking for! As Monkeh mentioned, the ELCB does not protect your body effectively. On the other hand, an RCD gives body protection and in most cases can save your life (not all cases, but most).

[T4P]

Do all RCD's have a Test button ?
I have no idea whether mine's a RCD or ELCB i but think it probably is a RCD since this building was constructed in the 1970's .  ( But it looks very old and very flimsy now )
It is so sensitive that when something goes even slightly wrong ( like a open circuit tungsten bulb ) it just TRIPS !
Well there was this once that a tungsten bulb ( don't know why they still exist in my house )
filament was touching the glass ( shouldn't it be OKAY ? )
and when switched it glowed WHITE for a few miliseconds before all the breakers tripped . ( Right , the incoming service 100amps MCCB , unchecked "neutral line" , unchecked RCD and the 13amps MCB of course . )

[Monkeh]

An RCD will not trip from a bulb blowing. It cannot.

[T4P]

An RCD will not trip from a bulb blowing. It cannot.

But mine did . I have no idea why it did .

[Monkeh]

An RCD will not trip from a bulb blowing. It cannot.

But mine did . I have no idea why it did .

Unless that bulb is in an earthed enclosure, shattered, and the filament fell on the enclosure, there's no way a real RCD (an ELCB might behave differently.. we don't use them now.) could trip.

[electroguy]

An RCD will not trip from a bulb blowing. It cannot.

But mine did . I have no idea why it did .

Unless that bulb is in an earthed enclosure, shattered, and the filament fell on the enclosure, there's no way a real RCD (an ELCB might behave differently.. we don't use them now.) could trip.

Maybe there was a short circuit, so the current exceeded the RCD and it tripped (ie: it tripped because of current, not because of an earth leakage...)

[SeanB]

RCD's do trip with a very large current flow, as they are not wound perfectly, but have a very slight imbalance, and the high current ( well above the rated carry current, but well within the must break fault current) generates enough sense current to trip them. think of this being an extra safety feature, as it ensures a fault will both trip the overcurrent breaker, but will also ensure the system has the capacity to break the fault if the fault is too large for the overcurrent device ( can be if the fault is within 3m of the breaker, as there is a built in assumption that there will be no faults within 3m of the breaker, and the rating is sized so) the extra contacts will help break the arc.

Earth leakage breakers are not easily found, as they were pretty much only used in industrial applications, almost never domestic use. They were used only if the supply could be isolated from ground and made to float at a defined potential to enable faults to be detected by current flow. Mostly used still on medical isolated supplies, with 1 transformer and monitor per outlet socket.

If the earth and the piping is well bonded, but is floating, then you need to call the supply authority, as they have a broken earthing point in their system that feeds your house, and they need to fix it. The 3 wire power system in the house ( Line, Neutral and Protective Earth) is made from a PME system on the pole supply where there is a Live ( 1 of 3 phases) and an earthed neutral wire, which is provided to the customer side by joining the customer neutral and earth together, and providing an extra earth connection direct to ground at the customer premises. All this is on the supply side before the meter, and is the suppliers responsibility. Most common fault is a corroded ground rod, or a broken earth wire from a massive fault. ( earth wire is allowed to be a certain amount smaller, and if it corrodes a lot it can be blown open by a short) Call the supply authority.

[Monkeh]

RCDs are not designed to trip under overcurrent situations and the chances of them doing so are pretty slim..

[IanB]

RCDs are not designed to trip under overcurrent situations and the chances of them doing so are pretty slim..

If a combined RCD/circuit breaker is installed as primary protection in place of a normal circuit breaker then it will have the function both of RCD and over current protection in one device. Under these circumstances it could trip in the event of a blown bulb. The (normal) circuit breakers in my house here in the US do tend to trip when a bulb blows.

[Monkeh]

RCDs are not designed to trip under overcurrent situations and the chances of them doing so are pretty slim..

If a combined RCD/circuit breaker is installed as primary protection in place of a normal circuit breaker then it will have the function both of RCD and over current protection in one device. Under these circumstances it could trip in the event of a blown bulb. The (normal) circuit breakers in my house here in the US do tend to trip when a bulb blows.

In which case it's a: Not an RCD, and b: Totally pointless because he has a 100A MCCB (according to him, anyway).

As for your breakers tripping, that's because the American idea of a CPD is very poorly thought out.

[IanB]

In which case it's a: Not an RCD, and b: Totally pointless because he has a 100A MCCB (according to him, anyway).

As for your breakers tripping, that's because the American idea of a CPD is very poorly thought out.

I can appreciate that electrical standards vary between countries, but what is wrong with putting an RCD in the same enclosure as a circuit breaker? That is what they do, for example, with AFCIs.

Also, what is wrong with a breaker tripping when an excess fault current from a blowing bulb is present? Are you suggesting the breaker should react more slowly?

[Monkeh]

In which case it's a: Not an RCD, and b: Totally pointless because he has a 100A MCCB (according to him, anyway).

As for your breakers tripping, that's because the American idea of a CPD is very poorly thought out.

I can appreciate that electrical standards vary between countries, but what is wrong with putting an RCD in the same enclosure as a circuit breaker? That is what they do, for example, with AFCIs.

I didn't say it's wrong, I said it's not an RCD. And it's totally pointless because he already has a protective device for the installation (The MCCB) and the circuit (the MCB). You do NOT add extras for fun, it's bad design.

Also, what is wrong with a breaker tripping when an excess fault current from a blowing bulb is present? Are you suggesting the breaker should react more slowly?

Yes, it should react more slowly, and it would if their breakers didn't have a silly tripping profile which prevents a 15A device operating on a 15A breaker.

[IanB]

I didn't say it's wrong, I said it's not an RCD. And it's totally pointless because he already has a protective device for the installation (The MCCB) and the circuit (the MCB). You do NOT add extras for fun, it's bad design.

We don't really know anything about what Dave.S has. Most of what he writes is confused or speculation or wrong or just plain garbage.

Here in the US there is a main circuit breaker for the installation (e.g. 100 A), and then each individual circuit has its own breaker downstream (e.g. 15 A or 20 A for normal receptacles). These circuit breakers are individually replaceable in the main breaker box.

The historical tradition here was for GFCI devices to be installed externally in individual circuits (they replace a standard power socket and go in the same wall box). You install a GFCI as the first socket in a chain, and then daisy-chain the remaining normal sockets on the output terminals of the GFCI.

However, regulations are tending towards having GFCI protection installed automatically at source. Hence you can get a combined GFCI and circuit breaker that installs in the breaker box protecting the whole circuit and removes the need for an external separate GFCI. For example, like this: http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=100187456

[Monkeh]

I didn't say it's wrong, I said it's not an RCD. And it's totally pointless because he already has a protective device for the installation (The MCCB) and the circuit (the MCB). You do NOT add extras for fun, it's bad design.

We don't really know anything about what Dave.S has. Most of what he writes is confused or speculation or wrong or just plain garbage.

Yes, so let's make wild speculations and assumptions instead of working from what he's said. That's logical.

Here in the US there is a main circuit breaker for the installation (e.g. 100 A), and then each individual circuit has its own breaker downstream (e.g. 15 A or 20 A for normal receptacles). These circuit breakers are individually replaceable in the main breaker box.

So like any installation.

The historical tradition here was for GFCI devices to be installed externally in individual circuits (they replace a standard power socket and go in the same wall box). You install a GFCI as the first socket in a chain, and then daisy-chain the remaining normal sockets on the output terminals of the GFCI.

Insanity.

However, regulations are tending towards having GFCI protection installed automatically at source. Hence you can get a combined GFCI and circuit breaker that installs in the breaker box protecting the whole circuit and removes the need for an external separate GFCI.

Rather more sane, congratulations to them on finally catching up with the rest of the world.

E: Wait, 5mA? What happens if you sneeze at it or dare to connect a computer to the circuit?

[IanB]

E: Wait, 5mA? What happens if you sneeze at it or dare to connect a computer to the circuit?

That's easy. Computers are incompatible with wet areas 

[SeanB]

The illustrated item is designated for bathrooms - ie wet areas. So a likely thing is a hair-dryer or curling iron, where you want tripping at low current levels.

The USA is hampered by having old installations that have to be great grandfathered in, you still find KT wiring around with open wire on wooden beams, and it still is in use. New stuff had to be done such that it would work more or less with what was there, so the kludges that have appeared. It would be good to make compliance mandatory, but that would cost a huge amount, and no politician will do so as it would be tantamount to stepping in a grinder with no reward.

Here it went illegal years ago, the only grandfathered stuff is fuses with replaceable elements, and then to do any work the new stuff has to comply ( replace a 5A outlet with the same 5A outlet is ok, a new one with a switch where the old one never had one, or upgrading to 15A so you can use anything, needs to comply with current regs, so has to be to new standards with MCB, ELCB and insulation test for wire. Most electricians will only do so if they can do the rest of the installation to spec as well) as well as be cable in a conduit or with double insulated conductors. Sale of a building means compliance cert, so this does get upgrades done.

[Monkeh]

And when you need protection for a circuit supplying a non-wet area?

[SeanB]

30mA is what is used here in South Africa. Funny enough you get industrial RCD units for water heaters that can have a limit of 100ma or 1A, but they are not approved for any other use.

[IanB]

My GFCIs do not trip inappropriately with anything I have tried plugging into them. So I will worry about spurious trips if and when I encounter that problem.

I don't feel any need for GFCI protection in normal home areas away from garden/garage/bathroom so I'm not going to go round and refit my whole house with GFCIs.

[megajocke]

In response to the previous few posts in this thread, attempting electrical work in the home if you are not an expert is potentially dangerous. There are a few no doubt well meaning posts above suggesting home brew solutions made by people who perhaps know what they are doing. But suggesting such a course of action to someone who does not have the prior knowledge, training and skills to do such work is utterly horrifying 

Please, don't fiddle with this stuff, call an electrician. Even call the electricity company. In most countries they will do a free safety check for you and give you advice about what might need fixing.

For starters, if the voltage between neutral and the yellow/green wire is 126 V, then that is not a proper earth wire and you should not trust it. Stop here and get expert advice.

Also, it is important to be aware that the electrical installations in different countries may be very different.

In (some or most) Norweigan electrical installations the normal 230V loads are connected between two different phases of a 3-phase 230V supply. If the supply is perfectly balanced you'll have 133V (that is, 230V/sqrt(3)) between phase and ground as well as between "neutral" (which is actually another phase) and ground. Measuring 126V would be perfectly normal!

At least here in Sweden, having only ungrounded receptacles in some or most rooms is very common, and I suspect that this goes for other Schuko-using countries too. Grounded plugs fit in ungrounded receptacles, and the idea is that since there are no grounded items in the room you are safe as long as you don't touch two different defective appliances at the same time (which can be classified a double or even triple fault). This is no less safe than ungrounded non-doubly insulated equipment which relies on the same thing to get its second safety barrier. The plugs of this kind of equipment do not fit in grounded receptacles.

In new installations grounded receptacles are required, to which non-doubly insulated ungrounded equipment can not be connected. New equipment is required to be either grounded or doubly insulated. Doubly insulated equipment has plugs that fit in both grounded and ungrounded receptacles.

So, in the Schuko system you have the following kinds of receptacles:
ungrounded receptacles in rooms where the room itself is insulating (not used in new installations)
grounded receptacles: in rooms where ground is accessible, outdoors, kitchen etc. or recently everywhere
receptacles into which only doubly-insulated equipment can be connected (pretty uncommon)

Mixing ungrounded and grounded receptacles in the same room is not permitted in Sweden because this would introduce ground into the room, whose absence is relied on as the second safety barrier. (a Finnish poster earlier in the thread said the same thing applies for Finland) The receptacles into which only doubly insulated equipment can be connected can be mixed with the other kinds. They can be used in a room where ground is accesible, without requiring a ground wire to be available for the receptacle.

As for equipment and plugs there are three different kinds too:
grounded (fits in ungrounded and grounded receptacles): relies on the ground as a second safety barrier
ungrounded (fits only in ungrounded receptacles): relies on the insulated room as a second safety barrier.
doubly-insulated (fits in all receptacles): the second safety barrier is internal to the equipment.

Note that the way different plugs fit into different receptacles is opposite of that in the US, unless nongrounded US receptacles and plugs are understood to correspond to the doubly-insulated Schuko ones!

[alm]

In (some or most) Norweigan electrical installations the normal 230V loads are connected between two different phases of a 3-phase 230V supply. If the supply is perfectly balanced you'll have 133V (that is, 230V/sqrt(3)) between phase and ground as well as between "neutral" (which is actually another phase) and ground. Measuring 126V would be perfectly normal!

That's the reason why having someone knowledgeable on site is useful. Two phases from a three-phase supply would make sense, but makes it hard to draw any conclusions about the quality of the earth connection. The original problem was an apparent flow of current through kind.oslo's body, that current has to come from somewhere.

At least here in Sweden, having only ungrounded receptacles in some or most rooms is very common, and I suspect that this goes for other Schuko-using countries too. Grounded plugs fit in ungrounded receptacles, and the idea is that since there are no grounded items in the room you are safe as long as you don't touch two different defective appliances at the same time (which can be classified a double or even triple fault).

Does this also require water pipes and radiators to be floating? Any requirements about carpet impedance? It's not too hard to get a shock while touching just a single phase, although I've never bothered to put an ammeter in series to measure the current.

[IanB]

Does this also require water pipes and radiators to be floating? Any requirements about carpet impedance? It's not too hard to get a shock while touching just a single phase, although I've never bothered to put an ammeter in series to measure the current.

I've never been able to get a shock from touching a single live wire while in a dry room. There were many times as a teenager that I handled live wires while sitting or kneeling on a carpeted or wooden floor and never felt a thing. Unfortunately as a youngster one has no perception of danger at all and it was entirely easy to be careless about whether equipment was unplugged before working on it.

I imagine you would not be allowed to have any metal objects like water or gas pipes in a room where you are relying on room insulation to be a safety barrier.

[megajocke]

Well, the idea was that you wouldn't have any grounded objects.  Water pipes (if any) and radiators are usually coated in thick paint, but nevertheless there usually are exposed metallic parts. It seems that these details were conveniently overlooked. Or maybe you were just supposed not to touch the radiators at the same time as electrical equipment. I actually saw a note attached to an old fuse box which said: "Do not touch radiators or faucets at the same time as electrical appliances.", or something to that matter.

In new installations non-grounded receptacles are not permitted, so this is becoming a non-issue albeit slowly. If I understood correctly, GFCI protection is also a requirement. It is typically done with one central GFCI protecting all normal circuits. I'm not sure when the electrical code was changed, but buildings from the mid-90's usually have ungrounded receptacles in "dry" rooms.