Discuss Metal lamppost in garden... TNC-S in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
58
Evening all,
Need some opinions on this one please:
TNC-S house, complete new install, all going to plan, nearly finished second fix, customer then arrives with a huge metal lamppost (bought from Frinton-on-sea promenade...) and wants it hooked up in the back garden.
What is the general consensus on this - my concern is: in the event of loss is supply neutral, everything connected to MET, including that lamppost, will rise to a voltage, anyone touches it may get a shock?
Or, will the fact it's planted in the earth keep any possible voltage down?
Am I making something out of nothing here or would this be safer as a TT?

Any thoughts welcome.
 
Ok, so touching a radiator bonded in the house in no different to touching a lamppost bonded in the garden? Is that what you're getting at?
 
So I'm reading too much into it.
Thanks fellas. Never thought twice about domestic outside lighting before, but when something different comes along it makes you think twice...
 
This is probably a case of minimal risk. In general you are not constantly handling a lamppost, as opposed to hand held electrical equipment, and so the risk of neutral loss fault occurring and it being a risk due to contact are low.
Bonding will have limited effect since the potential you are trying to eliminate is between earth and the supply and bonding will only limit the PD between the MET and the supply.
Within a property there should be no potential differences because the bonding connects all sources of potential difference together. Outside a property without installing conductive mats in the ground you cannot avoid being in the presence of a nominal 0V from true earth and so the risk is increased.
 
The post will propably act as one big rod.
This was suggested many years ago by the ILE but was felt the column would be unreliable as an electrode due to corrosion, protection on the column to prevent corrosion and the means of bedding it in the ground.
 
This is probably a case of minimal risk. In general you are not constantly handling a lamppost, as opposed to hand held electrical equipment, and so the risk of neutral loss fault occurring and it being a risk due to contact are low.
Bonding will have limited effect since the potential you are trying to eliminate is between earth and the supply and bonding will only limit the PD between the MET and the supply.
Within a property there should be no potential differences because the bonding connects all sources of potential difference together. Outside a property without installing conductive mats in the ground you cannot avoid being in the presence of a nominal 0V from true earth and so the risk is increased.
Thanks Richard, this makes sense.
 
Well you cud'a knocked me down with a feather when I saw this, normally it's only sheds that bring people out in a cold sweat when TNCS is mentioned. I think I've pointed out before that those who come over all unnecessary at the mention of a shed never seem to get that queasy feeling with other outdoor installs.
So good on'yer Weevilward, shows you are thinking about what you are doing rather than just following the herd and subscribing to myths.
 

Reply to Metal lamppost in garden... TNC-S in the Electrical Forum area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock