individual earth connections on sockets IN NETHERLANDS

[svouts]

Hi,
I am replacing two old surface-mounted sockets in the attic room where there is no earth cable.
The sockets are a just above the skirting and bellow run two central heating steel pipes (hot and warm water) mounted with metal brackets on the wall.

Can I connect an earth cable for each new socket to the metal pipes below?

The central heating pipes are hidden in a decorative grille enclosure along the wall so the earth cable will not be exposed, if I connect the socket and the pipes.

Many thanks

 

[bernardgreen]

Can I connect an earth cable for each new socket to the metal pipes below?

NO you cannot use the pipes as an Earth

You need to install new cable that has a proven Earth connection to the Earth bar in the consumer unit.

 

[oldbutnotdead]

What he said. Have a careful look at the existing cabling- is it a proper conduit system (so originally earthed via the conduit) or is it pyro cable (so earthed through the copper sheath) or is it a horrid lash-up?

 

[winston1]

What country is this?

 

[ericmark]

Each country has its own rules, without stating the country can't really answer.

 

[svouts]

Hi, it is in Netherland's.
I checked the consumer unit and has two earth cables, one to the earth bar and one to the water supply pipe in the basement.

The attic has still an old dual cable black and red with no earth. The room was used before for storage. I have now renovated the attic and the new sockets will be used to run a TV and a floor lamp.

 

[ChrisEll66]

Assuming very similar rules to France ....and applying logic..... If it's simply a light and TV (and assuming the cabling etc good for the load) - install modern euro 2 pin sockets. TV and most lights are class 2 with 2 pin plugs.

 

[Ragnar_AT]

Yes, as far as I know the Netherlands have no requirements for earthing existing installations, unlike many other European countries. Just fit back boxes and new flush sockets without earth clips („ongeaard stopcontact“).

And maybe while you‘re at it, replace all the existing cables in the loft with singles in flexible conduit so an earth can be added later if required at some point in the future.

 

[svouts]

Many thanks for your comments. I had already bought sockets with earth connection, which simply are not connected to earth. The cable is also new around the room with earth connection again not used.

Basically, I have a ready to earth wiring in the attic where the earth cable is not connected. In a future rewiring it will be ready!

 

[Pat ex]

Many thanks for your comments. I had already bought sockets with earth connection, which simply are not connected to earth. The cable is also new around the room with earth connection again not used.

Basically, I have a ready to earth wiring in the attic where the earth cable is not connected. In a future rewiring it will be ready!

If I was plugging an appliance into a 3 pronged socket, I would assume one of them was a reliable earth.

 

[FrodoOne]

Hi, it is in Netherland's.
I checked the consumer unit and has two earth cables, one to the earth bar and one to the water supply pipe in the basement.

The attic has still an old dual cable black and red with no earth. The room was used before for storage. I have now renovated the attic and the new sockets will be used to run a TV and a floor lamp.

Assuming it is a TN-C-S system, there ought to be a connection from the "Earth" bar to an "Earth Electrode" - with the "Earth" bar also connected to the "Power Company" incoming Neutral Supply conductor (Bar).
However, "older" systems often used existing metal water pipes as the "Earth Electrode"
In either case, all metal pipes entering the premises ought to be "Bonded" to the "Earth Electrode"/Neutral.

Most countries now allow any suitably provided "Earth Electrode"/Neutral connection to be extended (by individual "Earth" wires) to the "Earth" connection of any Socket-Outlet which requires it.

 

[bernardgreen]

Assuming it is a TN-C-S system, there ought to be a connection from the "Earth" bar to an "Earth Electrode" -

I am not sure that there ought to be a connection

If there is such a connection to a low impedance ground electrode then the size and routing of the cable requires careful consideration,

In the event of a broken Neutral in the local supply network then a bond between a Neutral derived "Earth" and Ground can have to carry a very large current creating a risk of fire if the connection overheats.

 

[ChrisEll66]

It's less than ideal using 3 pin sockets if there's no earth. I can't say what rules apply in NL but the general principle is to use 2 pin sockets with no earth. It's impossible to plug class 1/earthed items into it is thus generally viewed as "conforming".

 

[FrodoOne]

I am not sure that there ought to be a connection

If there is such a connection to a low impedance ground electrode then the size and routing of the cable requires careful consideration,

In the event of a broken Neutral in the local supply network then a bond between a Neutral derived "Earth" and Ground can have to carry a very large current creating a risk of fire if the connection overheats.

"If there is such a connection to a low impedance ground electrode then the size and routing of the cable requires careful consideration,"

Quite so!
The conductor to the "Earth" electrode should be as direct as possible (without sharp bends or loops) and of the appropriate thickness, as required by the regulations concerned.

See

particularly from 21:50 to 28:35 for "System Grounding and
from 28:35 to 34:50 for "Equipment Grounding".

"In the event of a broken Neutral in the local supply network then a bond between a Neutral derived "Earth" and Ground can have to carry a very large current creating a risk of fire if the connection overheats."

You may be "surprised if you measured the resistance of a "typical" Earth Electrode.
Unless it is an UFER Ground", it is unlikely to be less than 25 Ohms - in which case the current (in a 240 V system) would be less than 10 A and the "problem" would become apparent fairly quickly.

It's less than ideal using 3 pin sockets if there's no earth. I can't say what rules apply in NL but the general principle is to use 2 pin sockets with no earth. It's impossible to plug class 1/earthed items into it is thus generally viewed as "conforming".

In North America, Non Grounded 3-Pin socket Outlets are permitted, as long as they are
"Protected" by a GFCI (RCD/RCBO) and
"Ladled" as such.

 

[bernardgreen]

You may be "surprised if you measured the resistance of a "typical" Earth Electrode.

Having measured quite a few I doubt I would be surprised

in which case the current (in a 240 V system) would be less than 10 A and the "problem" would become apparent fairly quickly.

How would the "problem" become apparent ? 10 Amps flowing though a conductor as small as 1 mm² is not going to have any visible heating effect on the cable,

it is unlikely to be less than 25 Ohms

In the vast majority of domestic ground rods ( Earth Electrodes ) it could be higher than 25 Ω. up to 200 Ω is acceptable. In reality an impedance of 1,600 Ω would still cause a 30mA RCD to trip before the CPC ( earth wire ) in the property reached 50 V above local ground potential

I = V / R
50 / 1600 = 0.03125 A = 31.25 mA

That is the theory for tripping an RCD when there is a Live to CPC fault in the house. The RCD will react to the Earth Leakage from Live to CPC and open circuit the Live

In the case of a lost Neutral that theory does not apply.
Take the case of a PME ( TN-C-S ) supply

The incoming Neutral and the CPC are connected together in the cut out ( before the main fuse )

A Ground Electrode and any metallic pipes coming to the house are bonded to the CPC.

There is no safety device monitoring the current flowing along the CPC from Neutral to Ground

If the pipes bringing water and/or gas to the house are metal then the impedance can be very low and could be as low as 0.1 Ω.

Depending on how the Neutral is "lost" the current in the CPC could be hundreds of Amps

A broken Neutral that then shorts to a Phase in the local network cable could cause over 2000 Amps to flow in the CPC before the safety devices in the substation react to the over current on the affected Phase,