Is It Ok To Add An Earth Wire?

[4.real]

I have a Toshiba shower heater connected via a National circuit breaker that has an ELCB built into the shower unit.

My house has only 2 pin wiring .No earth cables.

Is it ok to run an earth wire from the shower unit to a copper coated rod I have hammered into the ground? [2 meters long ].

Thanks ,in advance, for any response.4.Real

[Crossy]

Absolutely

You should also add an RCD (ELCB, Safe-T-Cut) to your power board if you don't already have one.

This may be worth a read http://www.crossy.co.uk/wiring/2pin.html

[doglover]

It appears that this will be a rapidly opened and closed case so I'll take a risk at being labelled a thread highjacker. I also have an earthing question Crossy. My electrical code book is covered with a thick layer of dust in another country and I never did alot of ground rod pounding anyway and have been out of school too long too access my memory.

My house wiring is already grounded via a ground rod but I will have to pound another one as the electrician did not include a ground wire in the conduit that feeds my garage wiring. Due to some sort of blockage I cannot pull another ground wire out through this conduit. I have two water pumps and a few 3 prong receptacles that require grounding via the newly pounded ground rod. The ideal location for me to pound this ground rod (for wiring convenience) would leave a distance of 17 metres between the two ground rods. Is this ok?

[powderpuff]

Absolutely fine.

A lot of guys on here would say just make sure the 2 ground wires/systems remain isolated.

I personally have mine ganged together but that is my choice.

You are 99.9% safer than most people in Thailand!!!! Congrats.

Edited January 24, 2011 by powderpuff

[InterestedObserver]

Absolutely fine.

A lot of guys on here would say just make sure the 2 ground wires/systems remain isolated.

I personally have mine ganged together but that is my choice.

You are 99.9% safer than most people in Thailand!!!! Congrats.

If Doglover is referring to a dusty copy of the US National Electrical Code (NEC) he will find that separate grounding systems are not allowed for the same service entrance and a grounding (green) conductor must be run along with every circuit. Isolated grounding systems can be hazardous. However, this is Thailand (TIT).

Edited January 24, 2011 by InterestedObserver

[Crossy]

Indeed IO ^^^

This is where different countries have different standards, the UK permits (or even encourages) separate grounds in outbuildings, indeed exporting of a PME ground to an outbuilding is not permitted in many instances.

Your second rod is fine, as long as you have an RCD (ELCB) protecting the equipment at the far end. It simply makes your sub-main a TT installation, nothing against local regulations.

[4.real]

It appears that this will be a rapidly opened and closed case so I'll take a risk at being labelled a thread highjacker. I also have an earthing question Crossy. My electrical code book is covered with a thick layer of dust in another country and I never did alot of ground rod pounding anyway and have been out of school too long too access my memory.

My house wiring is already grounded via a ground rod but I will have to pound another one as the electrician did not include a ground wire in the conduit that feeds my garage wiring. Due to some sort of blockage I cannot pull another ground wire out through this conduit. I have two water pumps and a few 3 prong receptacles that require grounding via the newly pounded ground rod. The ideal location for me to pound this ground rod (for wiring convenience) would leave a distance of 17 metres between the two ground rods. Is this ok?

Bloody thread hijacker......

[4.real]

Absolutely

You should also add an RCD (ELCB, Safe-T-Cut) to your power board if you don't already have one.

This may be worth a read http://www.crossy.co.uk/wiring/2pin.html

Thanks for the info Crossy.

In ref to dog hijacker is there any limit to the length I should go [with green earth cable] to the grounding rod?

[Forkinhades]

not really a limit as such, what is important here is that you get a good external earth reading between 1 and 10 ohms ideally, and remember the further away you go with the rod, then the bigger the size of cable.

If you pm me with the details of your circuit, I will give exact sizes

ie size of load, size of cable

Edited January 24, 2011 by Forkinhades

[doglover]

Absolutely fine.

A lot of guys on here would say just make sure the 2 ground wires/systems remain isolated.

I personally have mine ganged together but that is my choice.

You are 99.9% safer than most people in Thailand!!!! Congrats.

If Doglover is referring to a dusty copy of the US National Electrical Code (NEC) he will find that separate grounding systems are not allowed for the same service entrance and a grounding (green) conductor must be run along with every circuit. Isolated grounding systems can be hazardous. However, this is Thailand (TIT).

1.My apologies to 4.love for hijacking your unfinished thread...lol. But I might as well roll with it now, hopefully something I ask also answers a question for you..

2.Thanks Mr.Crossy. My circuits are indeed protected with an RCD. If it wasn't for the reply from IO my hijacking would have stopped....

3. InterestedObserver sir....mine is the Canadian electrical code book but you jogged my memory a little and I believe the CEC to match with the NEC on this. However, my concern is not really matching any certain countries code but only to have optimal grounding for safety. Could you (or anyone else who so desires)take the time to jumpstart my brain as to why isolated grounding systems can be hazardous? ( something to do with creating a circuit I believe) And suggest what you would do different from my proposed plan given the blockage of the conduit feeding the garage situation?

[InterestedObserver]

Doglover,

Since you are in talking about a Thai electrical system, using two or more separate ground rods and grounding conductors is acceptable. Just install a ground rod for your garage wherever it is convenient. Two a more ground rods that are not bonded together can develop a voltage difference between them resulting a shock hazard. Dairy farms are particularly sensitive to this stray voltage.

[Forkinhades]

@ IO, agreed, a potential difference is possible, but there is a UK regulation against it, I do not have my UK regs book to hand, but I will make some enquires. From memory I think that you could possibly introduce an earth fault that otherwise was not there. Myself I think I would bond them together though. Maybe Crossy can a little more input on this.

reason for edit, another post was posted before I had time to finish

Edited January 24, 2011 by Forkinhades

[Lite Beer]

Is it ok to run an earth wire from the shower unit to a copper coated rod I have hammered into the ground? [2 meters long ].

I would have that it would be compulsory.

[4.real]

Thanks all for your input .....[including the hijacker]

4.real

[Crossy]

@ IO, agreed, a potential difference is possible, but there is a UK regulation against it, I do not have my UK regs book to hand, but I will make some enquires. From memory I think that you could possibly introduce an earth fault that otherwise was not there. Myself I think I would bond them together though. Maybe Crossy can a little more input on this.

Pretty much the case gents. The problem is the potential (arrgh) of touching two different grounds.

In the event of a L-E fault current will flow down the ground rod and the ground voltage will rise due to the ground resistance, often this voltage can get rather high before the protective device opens. If you happen to be in contact with the 'live' ground and a 'real' ground at the same time things can get bad

This is the reason for equipotential bonding, to ensure all grounded metalwork is at the same potential (they're connected together).

So long as all earth stakes that serve a particular building are connected to a single main earth terminal (MET) there is no danger, it's common to use multiple earth pits in commercial buildings in order to get the ground resistance down to acceptable levels, they're all linked to a single MET.

In your outbuilding it's actually safer to have a local ground, if you do export the house ground and there's a fault any metalwork connected to the ground terminal will rise towards L potential, if there's a water pipe in the outbuilding it will remain at 'real' ground, ouch if you touch both. This is the reason that exporting PME earth is prohibited in certain circumstances.

[Forkinhades]

^ cheers crossy, very good explanation

[InterestedObserver]

Try to explain equipotential bonding (grounding) to a Thai or any residential electrician. That's why it is so much easier to just run the little green wire everywhere. In industrial facilities equipotential bonding, ground loops and stray voltages are a continuous problem for reliable data communications as well as safety.

Edited January 25, 2011 by InterestedObserver

[powderpuff]

So therefore my solution - ganging all my grounds together is sensible.

But were I living on a farm - with a pump house 30 meters away I would just pound a ground rod , clamp it & go on about my business. (isolated grounds).

[Forkinhades]

@ pp Yes just make sure you have a main RCD/ELCB for the outbuilding, within the outbuilding