Supply to agricultural shed

[tom6]

Hi Guys,

I am helping out a friend at the moment i dont often get involved in industrial stuff so looking for some advice.

At the moment there is a 60ftx30ft thats used as a workshop currently its a 3 phase 100 amp supply - it gets minimal use as the workshop is more used as a store these days and likely hood of it being used for anything more in the future is slim.

Now, there has been another shed 80ftx40ft put up next to it (as a new workshop), they are in the process of finalizing the build. To the rear of the new shed is the pole that the cable supplying the existing shed comes from i.e. the pole is currently about 30 metres from where the entry point into the new shed is, and 60 metres from the entry point into the old shed.

So, the client has asked if there is any reason why we cannot take a 3-core armoured cable (35mm to keep in line with what supplies the old shed) to the new shed, tied in after the meter but before the CU in the old shed.

The current earthing setup of the existing shed is TN-C-S however it would be preferable in this situation to use TT system at the new shed if taking a supply from the old.

The cost of having a new supply from the pole to the shed has been quoted at 3.5k, it might be that it is the best and cleanest option. I just want some more information on it to go back to my mate with as it isnt something im dealing in everyday.

One other point there is no livestock whatsoever and never will be on this farm (well in our lifetime anyway!)

If i have indeed missed anything just let me know Thanks in advance.

 

[Leesparkykent]

Where's the meter? Is it in the old shed?

 

[tom6]

Where's the meter? Is it in the old shed?

Yeah its in the old shed...which is my eyes isnt ideal..

 

[Leesparkykent]

Yeah its in the old shed...which is my eyes isnt ideal..

How come? How far is the DB in the old shed from the meter? So you are going to have to install a new cable from old shed to the new shed if that's where the meter position is.

 

[davesparks]

Why do you want to ditch the TNCS connection? 35mm 3c will easily cope with the bonding requirements of a 100A supply.

Out of interest would it not be better to take a three phase supply to the new workshop?

 

[tom6]

Yeah exactly we will run a new cable from the old shed to the new shed. The DB is on the same mounting board as the meter less than a meter away.

It just seems a bit untidy having the supply cable from the pole bypassing the new shed and terminating in the old shed then taking a new cable from the old shed to new shed. But in reality it doesnt matter if it saves spending a fortune to have DNO come out and just take a cable from the pole to the new shed.

If you cant envisage any issues with taking a cable from the old shed it seems the more sensible option!

 

[davesparks]

It's nice how you put so much faith in a bunch of people you've never met,

 

[tom6]

Why do you want to ditch the TNCS connection? 35mm 3c will easily cope with the bonding requirements of a 100A supply.

Out of interest would it not be better to take a three phase supply to the new workshop?

Sorry i should have mentioned that ideally i would keep the TNCS connection, i just wasnt sure if this would cope with the bonding therefore making it independent was the route i chose to go when putting together the original post here, but it was a question i had meant to ask! So thanks for that

He has been quoted 3500£ for them to install a new supply which seems ridiculous if we could just tie it into the old shed.

 

[tom6]

It's nice how you put so much faith in a bunch of people you've never met,

If you cant have faith in trusted members then who can you! Its just good to get some different opinions and views

 

[davesparks]

Sorry i should have mentioned that ideally i would keep the TNCS connection, i just wasnt sure if this would cope with the bonding therefore making it independent was the route i chose to go when putting together the original post here, but it was a question i had meant to ask! So thanks for that

He has been quoted 3500£ for them to install a new supply which seems ridiculous if we could just tie it into the old shed.

You could always get your regs book out and check the requirements for bonding, which you will find is 10mm for a normal 100A supply and your cable has a third core of 35mm to serve as a bonding conductor.

And what are they going to do for that £3.5k? How does it compare to what you are planning to do?

 

[Leesparkykent]

Yeah exactly we will run a new cable from the old shed to the new shed. The DB is on the same mounting board as the meter less than a meter away.

It just seems a bit untidy having the supply cable from the pole bypassing the new shed and terminating in the old shed then taking a new cable from the old shed to new shed. But in reality it doesnt matter if it saves spending a fortune to have DNO come out and just take a cable from the pole to the new shed.

If you cant envisage any issues with taking a cable from the old shed it seems the more sensible option!

You don't really have a choice unless you get the DNO in to move the supply or add another to the new shed.