Earth Rod Requirement?

[Ahr35181]

We are supplying 4 metal container huts from a 3 phase board with no neutral. To provide 230V consumer unit supplies we are using a 400V to 230V TX, with the neutral linked to earth on the secondary. The supply to the TX (which is located in one of the containers) is 2 phase 400V TNS. We have a main earth bar in the supply container connected to the supply cable SWA, with MEBC running to all containers. All 230V sockets will have 30mA RCD protection.

Is there a requirement for installing earth rod/s in this application? All our other LV step down TX’s have neutrals linked to earth, but this installation is slightly different.

Thanks in advance,

Alan

 

[dpc]

Where are they installed?

 

[Ahr35181]

Hi dpc,

The 'containers' are installed outdoors in a fenced off area, weather or not this makes any difference?

 

[dpc]

What country?

 

[Ahr35181]

UK

 

[ScottyUK]

Ahr35181,

For your RCD protection to be effective, there has to be a path through 'earth' rather than through the earth conductor. If your neutral is connected to the main earth bar in the container, then you must provide a connection to 'earth' from this point.

 

[jbartos]

Suggestion: The earth rod is normally applied to provide the earth buss connection to the earth. The earth rods are standardized, governed by industry standards.
Visit

http://www.web-mantra.com/thrilecinternational/products/earthing/pointedearthrod.htm

Etc. for more info
Deep earth grounding will usually provide a low grounding resistance, e.g. 40 feet plus.

 

[dwraith]

You do not say if your main 400 volt supply has an earth connection. If it does then you should connect your earthing system to it. If not you have a TT system and you must provide an earth electrode. See IEE Regs Chapter 542.

 

[RajT]

I assume that all the containers are bonded to a common earth (via cable armour or a earth cable)point which in turn is connected to the Tx neutral.
If this is the case then additional earthing via ground rods etc is not required.
You should check that the RCD units are operating satisfactorily.