How to install an earthing system

[Siviwe Nkosana]

How can i wire an earthing system if I am installing a single phase panel board?

Basically what/which type of earthing do you recommend?

 

[Spoon]

Welcome to the forum mate.
Please can you expand on what you are planning on doing.
What is the existing earthing system?
Of course, whatever you are going will have to comply with the regs for South Africa.

 

[Pete999]

How can i wire an earthing system if I am installing a single phase panel board?

Basically what/which type of earthing do you recommend?

What type of supply's are you given by the supplier? TNCS, TNS, TT, PME. In SA?

 

[Siviwe Nkosana]

What type of supply's are you given by the supplier? TNCS, TNS, TT, PME. In SA?

It's mostly the TT supply
In some cases they use the TN-C-S
[automerge]1591978251[/automerge]

 

[Pete999]

It's mostly the TT supply
In some cases they use the TN-C-S
[automerge]1591978251[/automerge]

Do they not provide an Earthing terminal MET for you to utilize?

 

[Siviwe Nkosana]

Do they not provide an Earthing terminal MET for you to utilize?

As from the utility poles there's no earth in a feeding cable you only see an earth wire from a prepaid conlog meter which has an RCD and a sp MCB that is used for sub circuits.
You only see the earth from that wire which is going to the plug outlet

Here's an example of what i am talking about, take a look at a picture

 

[Pete999]

As from the utility poles there's no earth in a feeding cable you only see an earth wire from a prepaid conlog meter which has an RCD and a sp MCB that is used for sub circuits.
You only see the earth from that wire which is going to the plug outlet

Here's an example of what i am talking about, take a look at a picture

That's no help Mate sorry

 

[Siviwe Nkosana]

That's no help Mate sorry

Ok no worries Buddy as long as you've tried to assist, I appreciate that

 

[Pete999]

Ok no worries Buddy as long as you've tried to assist, I appreciate that

What exactly are you trying to do Mate?

 

[Siviwe Nkosana]

What exactly are you trying to do Mate?

I want to remove that plug outlet, i have shown you from the picture and install a single phase panel board

 

[pc1966]

The existing 3-pin socket should have some sort of earth connection, maybe back via the RCD enclosure to an earth rod. Do you know if that is the case?

Your safest option is to keep the existing RCD but you really need to consider what the maximum load is and how that will be limited in the event of a fault.
[automerge]1591992311[/automerge]
Do you know if the RCD is a RCBO (combined MCB and RCD)?

 

[Siviwe Nkosana]

The existing 3-pin socket should have some sort of earth connection, maybe back via the RCD enclosure to an earth rod. Do you know if that is the case?

Your safest option is to keep the existing RCD but you really need to consider what the maximum load is and how that will be limited in the event of a fault.
[automerge]1591992311[/automerge]
Do you know if the RCD is a RCBO (combined MCB and RCD)?

It's RCCB with a Sp Mcb and the Double pole MCB is mainly installed from the outside utility pole
[automerge]1592000150[/automerge]

The existing 3-pin socket should have some sort of earth connection, maybe back via the RCD enclosure to an earth rod. Do you know if that is the case?

Your safest option is to keep the existing RCD but you really need to consider what the maximum load is and how that will be limited in the event of a fault.
[automerge]1591992311[/automerge]
Do you know if the RCD is a RCBO (combined MCB and RCD)?

It's RCCB with a Sp Mcb and the Double pole MCB is mainly installed from the outside utility pole

 

[pc1966]

It's RCCB with a Sp Mcb and the Double pole MCB is mainly installed from the outside utility pole

Are you proposing to replace all of this with a distribution board, presumably one with a RCD incomer and then a few MCBs to have more circuits?

In the UK that would not be considered a DIY job by anyone here!

But in terms of your original question, if you have a double pole RCD as the incoming device you can use a rod for the earth in a TT style, though here it would have to be below 200 ohms impedance for 30mA or 100mA incomers, or below 167 ohms for a 300mA incomer.

Typically the use of 100mA or 300mA delay type RCDs would only be in conjunction with RCBOs or similar having 30mA trip for circuits needing additional personnel protection (e.g. socket outlets, lighting where users can poke fingers in to sockets while changing a bulb, etc).

But if your supplier provides an earth as well then generally you should use it.

 

[Siviwe Nkosana]

Are you proposing to replace all of this with a distribution board, presumably one with a RCD incomer and then a few MCBs to have more circuits?

In the UK that would not be considered a DIY job by anyone here!

But in terms of your original question, if you have a double pole RCD as the incoming device you can use a rod for the earth in a TT style, though here it would have to be below 200 ohms impedance for 30mA or 100mA incomers, or below 167 ohms for a 300mA incomer.

Typically the use of 100mA or 300mA delay type RCDs would only be in conjunction with RCBOs or similar having 30mA trip for circuits needing additional personnel protection (e.g. socket outlets, lighting where users can poke fingers in to sockets while changing a bulb, etc).

But if your supplier provides an earth as well then generally you should use it.

Finally you got it all right i want to add more sp MCB's so that i'mma be able to sub circuits

 

[pc1966]

One obvious question is are you legally allowed to modify that RCB box if it has some sort of electricity supply meter in it?

Another question is what total load are you planning and is the supply rated for that?

 

[Siviwe Nkosana]

One obvious question is are you legally allowed to modify that RCB box if it has some sort of electricity supply meter in it?

Another question is what total load are you planning and is the supply rated for that?

It is definitely illegal for me to modify the RCD box, but there would be no problem if i am taking that outgoing wire which is going to the plug outlets and use it as the power feeder to the Breakers that i will use for sub circuits

Lastly, the supply is undoubtedly adequate for the task as i'll be adding few breakers with at least 10 to 20 amps in rating and maybe i'll add only three single pole MCB's
I won't be adding any RCD because i already have the one installed along with a dp MCB

 

[pc1966]

That would be a reasonable approach. The only thing to need to be aware of is you will not get any significant selectivity with MCB in series.

For example if the supply MCB is, say, 20A and you fit a 6A light circuit then an overload on the lights (say a couple of time the MCB rating so in the 20-40A range or so) will trip just that MCB, but if you have a fault that exceeds the instantaneous magnetic trip of the 20A MCB (which could be as low as 3*In = 60A here) then by time the 6A MCB has opened to clear the fault the 20A MCB will already be past the trip point and will disconnect as well.

There is little you can do to get round this, but how troublesome it is depends on the fault currents you might see and the impact of a supply breaker trip. For workshops and similar I would normally suggest an emergency light (internal rechargable battery) so it is still partly illuminated and folk can see to get to the board and reset whatever has tripped.