And what's TN-C and PEN?

The "TN-C" is a power system nomenclature:
The first "T" means the power source is grounded by some of it's terminals.
The "N" means the principal protection of the accessible conductors (metal parts,...; those conductive, but not supposed to be connected to the electricity) by connecting them to a Neutral wire (so when a fault happens, this connection prevents a dangerous voltage from building up; indirectly it is the Ground, as the Neutral is grounded)
The "-C" means there is just a single conductor used for both functions: Power current Neutral connection (N) and the protection connection (PE), so the letters then are the combined "PE+N"="PEN".
In modern installations (according to the present standards) this common connection ends in the main breaker panel, where it gets separated to "N" wire (light blue per European standard) and "PE" wire (yellow/green and/or bare metal) wires, so becoming a "TN-S" system.

beside of that, the older installations were "TT" (so grounded power source, PE interconnection as the primary fault voltage buildup)
or in installation where a power interruption is by itself a safety hazard (the hospitals, magnetic cranes,...) "IT" (insulated source, PE interconnection to prevent dangerous voltage buildup), where a single insulation fault does not need the power to be immediately cut (an insulation monitor just sounds an alarm)

In the uk we have 2 systems one called PME where the neutral and earth are joined at the main incoming position also if power is overhead distribution every 7th pole has a conductor from neutral to an earth stake at the pole base. The other system is where the house earthing is via the metal sheath of the underground service cable the earth and neutral are separated completely. UK regulation state that earth and neutral are run as separated throughout the house or any other premises

We just have our own grounding below our breaker panel.

When considering a safe Earthing practice, the following must be considered :

 - If Phase shorts to PE on an end device, good Earthing shall allow high short circuit currents to immediately trip the breaker. That means for example >160A on an ordinary 16A circuit in Europe, 300A on 15A circuit in the US, 320A on a ring circuit in UK

 - If short circuit current is not available due to resistance in the point of isolation breakdown, the Earthing shall keep the accessible metal at safe voltage

 - Single Conductor break fault should never cause unsafe voltage to appear on accessible metal

 - Currents through unintended paths (stray currents) may cause a fire if they heat conductors on their way there

From there, evolved 2 relatively safe systems (ones with Earthed supply Neutral) :



TN-C-S and TN-S :

Neutral is Earthed at the power source (secondary of HV to LV transformer), but Neutral and Earth are separate on the end circuits to which stuff is connected. In TN-C-S, the separation is normally in the most upstream panel on the user's premises. In TN-S, they are separate all the way from the transformer, with the only place where they are together is the transformer itself

The point where Neutral and Earth part their ways must be Earthed by itself (by connection to Earth rods in that location for example), so that a broken PEN conductor before this place cannot lead to dangerous voltages on PE conductors

In the US it is the Neutral bar in the user panel, to which both N's (white) and PE's (bare) are connected together

In Israel it is the main supply Neutral, which is connected by a jumper to a main Earthing busbar (big Copper bar), at the entrance to the panel. The jumper goes to the main Earthing bar, to which all local Earthing and Bonding are connected

In other places i dont know



T-T :

Neutral is Earthed at the transformer but nowhere else. It is supplied merely as Neutral to everywhere

Earthing is done ultimately by local Earthing electrode at the premises, which is not connected in any way to Neutral. Very low Earthing resistance (good Earthing) is required to provide high short circuit currents and keeping touchable voltages low if the current is too low, as there is no complete Copper path from the short circuit to the source Neutral as in TN-* systems



The unsafe variant is TN-C, which is present in places in many places from the (...) block - Russia and East Europe places. There Earth and Neutral are the same wire, maybe up to the entrance to the premises, maybe inside the premises too, without additional Earth connection where they separate into Neutral and PE. In the worst case, they are combined right up to the wall socket, with a jumper between N and PE holes of the socket

This is sometimes done in the US too, and possibly in other places, as a hack - not as a legitimate repair :

Old house, no Earthing provided in circuits. Plugging 3 lamp receptacle tester into a receptacle shows that there is no Earth, and plugging a PC (or verious other electronics) in there makes their metal enclosures shock a little. To fool the receptacle tester (to fool inspections, ..) or to prevent the Pichu from the computer, some bright spark connects a jumper from PE hole to N inside the receptacle

The 3 lamp tester now shows that everything is ok

The computer is not shocking anymore

But let there be a bad connection somewhere in the N wire, then without any additional fault, the computer will now not give a little Pichu, but possibly kill whoever touches it

There is absolutely NO other electrical system in which a disconnected/broken wire alone, without presence of an actual isolation fault at the same time, can cause dangerous voltages to appear on touchable metal stuff that is supposed to be Earthed

Additional concern would be about somebody doing repairs and swapping N and L. It is not very nice thing to do in building wiring, as lamp switches now open the N instead of L. But for plugged in appliances it does not matter much. Except now, the jumper connects L to the PE hole in the socket, so everything metal is shocking at direct big Phase, without any fault present at all

And I wonder why RCD breakers are unheard of here.
The most common thing related to an RCD breaker is a GFCI breaker or a GFCI outlet upstream of more outlets.
This topic has really been off-topic compared to the original question, How much LED lighting do you have?

That are different names to the same functionality.. Tho for what i know the implementation is different as well, US ones use Elctronics while ours are entiely Electromechanical

My home : No LEDs in AC-powered lighting. Few LED lamps and strings in collection. Lots of discrete component LEDs as in electronic components laying around

That are different names to the same functionality.. Tho for what i know the implementation is different as well, US ones use Elctronics while ours are entiely Electromechanical

My home : No LEDs in AC-powered lighting. Few LED lamps and strings in collection. Lots of discrete component LEDs as in electronic components laying around

Me too, I have at least 300 of a blend of White, Purple, Assorted color, Salvaged, Color changing...

That are different names to the same functionality.. Tho for what i know the implementation is different as well, US ones use Elctronics while ours are entiely Electromechanical

If it is only electromechanical or if an electronic is needed depends on the required sensitivity. 30mA, so the requirements in the EU for sockets accessible to untrained people (homes, general offices; harsher industrial environments do not have to meet that, but then all people allowed to access the premise have to be trained in the basics of an electrical safety, at least per our regulation), is still possible to reach just using an electromechanical implementation, so indeed the vast majority of RCD's is just electromechanical.
When better sensitivity is needed, the plain electromechanical system would get false tripped by noise and/or capacitive currents, so an electronic filtering out just the mains frequency resistive phase current component (only that is caused by faults and the sensitivity level applies to this) requires an electronic to really reach that selectivity to real faults. What I've see, in the US 10mA or 6mA sensitivities are quite common in the "GFCI sockets" and that already requires the advanced filtering. Usually the system has two triggers: One electromechanical set at the 30mA or so and then a second one electronic filtered with lower sensitivity threshold (the 10 or 6mA). The main reason is, the electronic has longer delay (to really reach the required selectivity), so the electromagnetic trigger provides there the fast response for the higher fault current levels.

Conversion to LED is progressing, now with TCP 5000K 8.5w A19 shape bulbs for the latest 6 sockets converted.  Just about everything will be 5000K once I'm done.  Much nicer than the dingy 2700K CFLs (don't get me wrong, actual incandescent is second to none) or the too-blue-for-many-places 6500K daylight CFLs. 

Conversion to LED is progressing, now with TCP 5000K 8.5w A19 shape bulbs for the latest 6 sockets converted.  Just about everything will be 5000K once I'm done.  Much nicer than the dingy 2700K CFLs (don't get me wrong, actual incandescent is second to none) or the too-blue-for-many-places 6500K daylight CFLs. 

Everyone except me is afraid of anything other than 2700K to 3000K.
For them to handle 5000K, The light would have to be super bright.

When better sensitivity is needed, the plain electromechanical system would get false tripped by noise and/or capacitive currents

There is the thing when you loop the circuit 2 times through a 30mA RCD (3 Phase RCD for 1 Phase circuit) to get 15mA sensitivity. And it still works correctly. I'd expect that 15mA or less still is reachable by EM construction

And in the US the GF receptacle only controls a limited part of the circuit (itself + maybe few downstream receptacles), so sees much less leakage than our 30mA RCDs that typically controll an entire house

I think that they use electronics as a means to make everything tiny to make it fit in a wall receptacle box. So the CT can be smaller as it only supplies the inout to some logic and not driving directly the tripping solenoid

Another thing about for GFCI receptacles is you can get the ones which the indicator light turns off when it is tripped, And the ones which have the indicator light turn on when it is tripped. I always think the latter if more dangerous because the light would have to bypass the GFCI protection to light.

Another thing about for GFCI receptacles is you can get the ones which the indicator light turns off when it is tripped, And the ones which have the indicator light turn on when it is tripped. I always think the latter if more dangerous because the light would have to bypass the GFCI protection to light.

It does not have to bypass anything (that is really not allowed), but it is controlled by extra "diagnostic" contacts (which are fully insulated and close and/or open, when the GFCI trips) and connected upstream before the GFCI.

Quote from: wattMaster on June 03, 2016, 10:43:54 AM

Another thing about for GFCI receptacles is you can get the ones which the indicator light turns off when it is tripped, And the ones which have the indicator light turn on when it is tripped. I always think the latter if more dangerous because the light would have to bypass the GFCI protection to light.

It does not have to bypass anything (that is really not allowed), but it is controlled by extra "diagnostic" contacts (which are fully insulated and close and/or open, when the GFCI trips) and connected upstream before the GFCI.

Can you draw a schematic? I don't get it.

Normally the GFCI contains a set of two power contacts, switching the Line and Neutral. The mechanism is so, the contacts are held closed by a kind of latch, while a spring pushes them open. Once a fault is detected, the latch releases, so that spring opens the contacts.
Now if there is the "diagnostic", the contact carrier just carries another small contact and this contact controls the power to the indicator: If it is in the position the main contacts are closed, the auxiliary is open, so there is no power going to the indicator lamp. Once the thing get triggered and the contract carrier makes the main powr contacts open, the auxiliary contact closes, so turns the power for the indicator ON, so the indicator lights.

In other words it is nothing else than another contact switching just the indicator lamp, but that contact is mechanically coupled to the main GFCI mechanism, so it just responds to it's mechanical position, nothing else. So a contact in series with a small lamp...