Bit quick advice please

[hightower]

Wiring a couple containers up, refrigeration units. External to factory unit, about 10m from incomer. TNCS supply, thinking we should be dropping a rod in at the containers, but additional to TNCS earth so not separating. Can anyone advise?

 

[Leesparkykent]

I would rod it separately.

 

[hightower]

That would then require RCD protection though

 

[Leesparkykent]

Is there not a board with RCD in the container?

 

[hightower]

No, the lights are rcd protected but not the fridge part. Just our worry is if it trips over a weekend that's a lot of stock lost so that's why trying to avoid RCD protection

 

[westward10]

Doubt it has a board they are just big fridges or freezers. You may want to avoid rcds because if they trip and no one is aware a lot of loss/money maybe at stake.

 

[Leesparkykent]

I just see containers when skimming through.... yes defiantly best not having it on an RCD.

 

[hightower]

Thanks Westward. So with that in mind do you think it would be sufficient to rod alongside the supply earth

 

[westward10]

There is a remote possibility of someone sensing a potential difference between the containers and true earth but I would say this is highly unlikely unless the containers are somehow not in contact with the ground.

 

[hightower]

So you wouldn't even rod it?

 

[westward10]

Are they sitting on concrete or touching the ground.

 

[Ian1981]

How are these fridges connected in?
Are they A standard plug into a socket or are they hard wired in to an outlet/isolator?

 

[hightower]

They sit directly on the ground which will be concrete. They are wired through a rotary isolator and 32A commando

 

[Ian1981]

It's interesting that then the 18th edition comes into play then all socket outlets upto 32 amp require 30mA rcd protection (unless that changes after consideration during the draft).
In the mean time your okay not to have rcd protected unless required by other means as you will know.

 

[hightower]

Yes Ian, I understand the requirements for RCD . My question is based around do I rod it or not, and if I do should I separate it from the TNCS earth

 

[Ian1981]

Yes Ian, I understand the requirements for RCD . My question is based around do I rod it or not, and if I do should I separate it from the TNCS earth

If you rod it then yes I'd separate it from the supply earth to eliminate any possible potential differences that may appear.
its a steel container is it?
Sounds just like a separate building(container) so tncs can be used and steel frame can be bonded to MET

 

[westward10]

Does it require a main protective bond. If you rod it and separate the earth you are in back to the rcd scenario which you need to avoid.

 

[hightower]

No bonding required

 

[westward10]

If there are no exposed metal parts I don't see the need for a rod.

 

[Ian1981]

happy days!