Farm Barn requires 3 phase + N + E!

[fochlegend]

Hi,

The barn in question currently has a 230V Supply, 3 core 16mm SWA is used for this. There is one ring main (32A) and three lighting circuits (3 x 6A) installed in the barn.

The farmer has fitted a new pressure washer in this barn that requires a 3PN+E supply (16A).

The supply to this barn comes from a 3 phase, N + E mains board about 50 metres away, I was hoping to change the three cores to a 3 phase 415v supply.

My query is...can i use an earth spike to earth the barns mains board or is the armour of the cable enough? And then to reinstate 230V to the barn should I fit a 415 to 230v Transformer? How do i work out what size of transformer I will need to do this?

Thnaks in advance

(a farm hating sparky)

 

[Lucien Nunes]

That's a fudge if ever I heard one. Might not be a whole lot cheaper than running a new submain with a neutral either. Earthing in agricultural premises may need special consideration to minimise voltage gradient, difficult to advise without site survey.

 

[Carlosfandango]

But you've said the pressure washer is TP N+E

 

[Deleted member 9648]

Hi,

The barn in question currently has a 230V Supply, 3 core 16mm SWA is used for this. There is one ring main (32A) and three lighting circuits (3 x 6A) installed in the barn.

The farmer has fitted a new pressure washer in this barn that requires a 3PN+E supply (16A).

The supply to this barn comes from a 3 phase, N + E mains board about 50 metres away, I was hoping to change the three cores to a 3 phase 415v supply. Where are you going to get a N from?

My query is...can i use an earth spike to earth the barns mains board or is the armour of the cable enough?depends on present earthing system And then to reinstate 230V to the barn should I fit a 415 to 230v Transformer?No,You will end up with a 230v 2 phase system,not a phase and neutral. How do i work out what size of transformer I will need to do this?

Thnaks in advance

(a farm hating sparky)

Replace the distribution circuit.

 

[Lucien Nunes]

Seems he wants to use all 3 cores of the existing cable as phases, leaving him without the neutral he now has, so only 400V. Then to supply 230V locally by stepping the 400V down. Sort of roundabout bodge I'd do to get something going in an emergency.

 

[Pete999]

So you have a 3 core 16mm SWA and you need 3P+N+Earth in the barn for the pressure washer, and if I'm reading your thread correctly you want to use the existing 3 core as a 3 phase supply, where are you getting the Neutral from?

 

[Lucien Nunes]

Deriving it from the TP supply with a DY tx...

 

[Pete999]

Deriving it from the TP supply with a DY tx...

Didn't see that bit I was a bit taken aback at the question, seems a bit heath robinson to me much better to run a new supply imo

 

[davesparks]

A single phase to 3 phase convert or would be cheapest.

We had them at the wholesale nursery where I had my first Saturday job, they ran the irrigation pump, potting machine and bulk elevator. The site only had a single phase supply

 

[Lucien Nunes]

That's the most sensible option but the economics will be dependent on the pressure washer starting and running loads, and whether the VD is just too great with the entire load on one pair of conductors. Specs needed...

 

[dave992]

Hi,

The barn in question currently has a 230V Supply, 3 core 16mm SWA is used for this. There is one ring main (32A) and three lighting circuits (3 x 6A) installed in the barn.

The farmer has fitted a new pressure washer in this barn that requires a 3PN+E supply (16A).

The supply to this barn comes from a 3 phase, N + E mains board about 50 metres away, I was hoping to change the three cores to a 3 phase 415v supply.

My query is...can i use an earth spike to earth the barns mains board or is the armour of the cable enough? And then to reinstate 230V to the barn should I fit a 415 to 230v Transformer? How do i work out what size of transformer I will need to do this?

Thnaks in advance

(a farm hating sparky)

Hi, would recommended that a new supply is installed to the barn, remember that a farm supply must be TT and with all correct RCD fitted. The cheapest thing to do is cant the farmer relocate the power washer or exchange for a single phase one??

Thanks

 

[Engineer54]

Hi, would recommended that a new supply is installed to the barn, remember that a farm supply must be TT and with all correct RCD fitted. The cheapest thing to do is cant the farmer relocate the power washer or exchange for a single phase one??

Thanks

Where in the world did you pick-up that that load of rubbish from??

 

[micknew]

Another DIYer (with no training) obviously.
S/B in the D|IY section.

 

[trev]

Hi, would recommended that a new supply is installed to the barn, remember that a farm supply must be TT and with all correct RCD fitted. The cheapest thing to do is cant the farmer relocate the power washer or exchange for a single phase one??

Thanks

Regulation number please.

 

[PEG]

...The rod-god has a point...i have been in the agricultural job most of my life,and i can definitely assure you they are not all TT,and some,have the barest minimum of residual contrivance doodahs...this may just be such a scenario...:conehead:

 

[Simonslimline]

remember that a farm supply must be TT and with all correct RCD fitted.

Have a read of section 705 in BS7671.