When is an earth rod required for outbuildings?

[ppelec100]

Hi guys,

I’m still reading up on GN8 slowly, and haven’t quite got to the earth rod for outbuildings section yet I haven’t checked if they even cover that…

I know earth rods or using structural steel is needed for TT systems when DNO doesn’t provide it, but when is it needed in non TT situations and when installing supplies for outbuildings?

I know it was required for EV chargers before PEN fault devices came along.

For outbuildings that have been supplied using TNCS systems isn’t it dangerous if you import the earth if there is utilities such as water or gas incoming metallic pipe? If you lose the neutral, the earthing of the system becomes live and you can simultaneously touch both pipes and exposed conductive parts. Would supplementary bonding to the outbuildings utilities help zero the potential difference?

Also, what if the outbuilding is supplying outdoor lights and if you’re able to touch that class 1 light during pen conductor loss whilst stood on the ground. Wouldn’t that be dangerous?

I’ve watched videos on this before from John wards and some other decent YouTubers but I always get mixed answers.

 

[buzzlightyear]

https://www.bing.com/ck/a?!&&p=0b0f674a85f5f3b6b11994d9351de0279fccd4cb7d7db48d81919f23c38643e8JmltdHM9MTczOTA1OTIwMA&ptn=3&ver=2&hsh=4&fclid=0798af7c-fad8-64cd-0b4d-bd0cfbe865af&psq=tt+out+building&u=a1aHR0cHM6Ly9lbGVjdHJpY2FsLnRoZWlldC5vcmcvbWVkaWEvMTY5NS9lbGVjdHJpY2FsLWluc3RhbGxhdGlvbnMtb3V0ZG9vcnMtYS1zdXBwbHktdG8tYS1kZXRhY2hlZC1vdXRidWlsZGluZy5wZGY&ntb=1

 

[ppelec100]

https://www.bing.com/ck/a?!&&p=0b0f674a85f5f3b6b11994d9351de0279fccd4cb7d7db48d81919f23c38643e8JmltdHM9MTczOTA1OTIwMA&ptn=3&ver=2&hsh=4&fclid=0798af7c-fad8-64cd-0b4d-bd0cfbe865af&psq=tt+out+building&u=a1aHR0cHM6Ly9lbGVjdHJpY2FsLnRoZWlldC5vcmcvbWVkaWEvMTY5NS9lbGVjdHJpY2FsLWluc3RhbGxhdGlvbnMtb3V0ZG9vcnMtYS1zdXBwbHktdG8tYS1kZXRhY2hlZC1vdXRidWlsZGluZy5wZGY&ntb=1

Thanks mate but this is to do with extending TT, im after the info about TNCS pen conductor loss

 

[buzzlightyear]

Thanks mate but this is to do with extending TT, im after the info about TNCS pen conductor loss

https://www.bing.com/ck/a?!&&p=1e5d8a604386c2d80b53a3aa5faddb0188737b00c5c6777d0d5f1a236aa585a7JmltdHM9MTczOTA1OTIwMA&ptn=3&ver=2&hsh=4&fclid=0798af7c-fad8-64cd-0b4d-bd0cfbe865af&psq=pne+fault+loss+on+tt+system&u=a1aHR0cHM6Ly9wcm9mZXNzaW9uYWwtZWxlY3RyaWNpYW4uY29tL3RlY2huaWNhbC90bmMtcy1zdXBwbGllcy1mb3Itb3V0YnVpbGRpbmdzLXRoaW5raW5nLW91dHNpZGUtdGhlLWJveC1uYXBpdC8&ntb=1

 

[buzzlightyear]

View: https://youtu.be/z7han_twcnw

 

[buzzlightyear]

https://www.bing.com/ck/a?!&&p=1587f25d8c153bad25529a28be2a36e16824180ac627bd2de7be1c91a499f542JmltdHM9MTczOTA1OTIwMA&ptn=3&ver=2&hsh=4&fclid=0798af7c-fad8-64cd-0b4d-bd0cfbe865af&psq=extranuous+parts+on+tt+fault+PME+SUPPLY&u=a1aHR0cHM6Ly9wcm9mZXNzaW9uYWwtZWxlY3RyaWNpYW4uY29tL3RlY2huaWNhbC9zdHJvbWEtY2VydGlmaWNhdGlvbi1zdXBwbHktY2hhaW4v&ntb=1

 

[buzzlightyear]

It's all expantery if you read between the lines..

 

[ppelec100]

https://www.bing.com/ck/a?!&&p=1587f25d8c153bad25529a28be2a36e16824180ac627bd2de7be1c91a499f542JmltdHM9MTczOTA1OTIwMA&ptn=3&ver=2&hsh=4&fclid=0798af7c-fad8-64cd-0b4d-bd0cfbe865af&psq=extranuous+parts+on+tt+fault+PME+SUPPLY&u=a1aHR0cHM6Ly9wcm9mZXNzaW9uYWwtZWxlY3RyaWNpYW4uY29tL3RlY2huaWNhbC9zdHJvbWEtY2VydGlmaWNhdGlvbi1zdXBwbHktY2hhaW4v&ntb=1

Thank you very much for those 2 articles and that video. The video was very informative. The first article pretty much told me what i was already thinking but the last article cleared things up for me.

Q1. I will assume this is the same with any outdoor electrical equipment such as lighting sockets etc... the thing is you could put an outbuilding supply in for someone and they'll tell you they're using everything inside only, but one day during summer they could take a fridge on extension outdoors, so it would be best to just TT the outbuilding to cover yourself?

Q2. based off TNC-S, say if you have an outdoor socket coming off the primary house building (no outbuildings involved) and its a TNC-S, then what? An RCD will not protect the user from being shocked as the RCD will not see the neutral as active (not sure i worded this correctly) therefore will not operate right?

Q3. I've seen that sticking TT earth rods in the ground is not that simple as it needs to be a certain distance away from the other service pipes or will it will induce voltage (again not sure if worded properly) on to other metal work and cause problems for other properties?

 

[Pretty Mouth]

Q1. I will assume this is the same with any outdoor electrical equipment such as lighting sockets etc... the thing is you could put an outbuilding supply in for someone and they'll tell you they're using everything inside only, but one day during summer they could take a fridge on extension outdoors, so it would be best to just TT the outbuilding to cover yourself?

I don't follow your logic here. Presumably you're talking about the event of a lost supplier's neutral. Why do you feel that outdoor equipment, fed via an extension lead, would be a concern if the extension lead was plugged into a socket at an outbuilding, but not a concern if the same was plugged into a socket in the main building? Surely the problems that an open PEN would cause exist in both locations.

 

[ppelec100]

I don't follow your logic here. Presumably you're talking about the event of a lost supplier's neutral. Why do you feel that outdoor equipment, fed via an extension lead, would be a concern if the extension lead was plugged into a socket at an outbuilding, but not a concern if the same was plugged into a socket in the main building? Surely the problems that an open PEN would cause exist in both locations.

Oh I was just trying to put it in to a real life scenario lol. The fridge wouldn’t reach outside without an extension lead. Yes the PEN conductor being loss is the main topic of discussion here. The question I was trying to ask is if some appliance that is class 1 is being used outside of the outbuilding on say the grass area then it’s a high risk as the user is within simultaneous contact of exposed conductive part and earth…

The client might do something like this without your knowledge because let’s face it they have no idea about all this and will put things outside without any thought so is it best to just install a rod to cover yourself under all circumstances?

 

[Pretty Mouth]

The question I was trying to ask is if some appliance that is class 1 is being used outside of the outbuilding on say the grass area then it’s a high risk as the user is within simultaneous contact of exposed conductive part and earth…

Yes, this would be a risk. But you asked the question specifically in the context of an outbuilding. Why do you feel that this is more of a concern when the extension lead is plugged in at an outbuilding? Exactly the same risk exists regardless of where the extension lead is plugged in, outbuilding or main property.

 

[ppelec100]

Yes, this would be a risk. But you asked the question specifically in the context of an outbuilding. Why do you feel that this is more of a concern when the extension lead is plugged in at an outbuilding? Exactly the same risk exists regardless of where the extension lead is plugged in, outbuilding or main property.

Yeah you’re right there, I think I might’ve just pitched off the different worst case scenarios to do with outbuildings and I attached the extension lead idea to an outbuilding though it can be applied to the main building too.

I guess the extension to do with a main property ties in to the question about an outdoor socket on the main building and a class 1 equipment plugged in and sitting on conductive earth too.

So how do you protect the user and cover yourself in these situations? Are broken pen conductors that rare that it doesn’t need to be thought about this hard? Would you push the client to have a pen fault device set up (same as the ones built in ev chargers) for an outdoor socket if doing a rewire , outbuilding supply or any outdoor electrical work if they’re on tnc-s.