supply to zoo!

[sparkattack]

hi, ive got to run a length of swa to a detached garage that the customer is changing into a mini zoo for a load of snakes and various other insects theyve got. At the moment there is a 3phase supply entering the building in swa in 2.5 and the sheath being used as an earth. i cant get a straight answer to the amount of current they are going to be drawing but they are going to find out about the current a vevarian uses and how many they are going to have but looks to be about at least 20. The run of from the house cu to garage is about 25meters. ive done cals and I was thinking about running a new bit of 3core 4mm or maybe even 6mm to be safe, what do you guys recon? anyone know about how much current these snake homes use? cheers

 

[septiclecky]

hi, ive got to run a length of swa to a detached garage that the customer is changing into a mini zoo for a load of snakes and various other insects theyve got. At the moment there is a 3phase supply entering the building in swa in 2.5 and the sheath being used as an earth. i cant get a straight answer to the amount of current they are going to be drawing but they are going to find out about the current a vevarian uses and how many they are going to have but looks to be about at least 20. The run of from the house cu to garage is about 25meters. ive done cals and I was thinking about running a new bit of 3core 4mm or maybe even 6mm to be safe, what do you guys recon? anyone know about how much current these snake homes use? cheers

In a local garden centre which sells small snakes, spiders and other foreign creatures normally have heat lamps in the enclosures.

So unless they give you anymore info it would be hard to say but I would be looking at 6mm minimum. But why would you want to run another supply if there is already a 3 phase supply in the garage?

 

[Manator]

To be honest it is almost impossible to design a circuit unless you have a maximum demand.

When you know what you will be designing to then you will know what size cable will be required, plus 30% for future additions. Pin them down to give you the total equipment they will need power to.

 

[sparkattack]

when a cable is run underground what is its deviation factor?

---------- AUTO MERGE Post added at 18:28 ---------- Previous post was at 18:28 ----------

just pvc swa of course

 

[philbas]

Shove 10mm in, the main cost here is installing it not the cost of the cable, so future proof it,

And dare I ask this, whats the earthing type?

 

[SLIPSHOD & SLAPDASH]

Putting aside what type of earthing arrangement, it sounds like the outbuilding may have a water supply and other services so a minimum of a 10mm earth may be needed back to the MET anyhow

 

[sparkattack]

yeah there is a water supply in there and it is a 3phase TNCS supply

 

[m4tty]

Are you exporting the earth on tncs or are you gonna tt the outbuilding?

 

[sparkattack]

was going to use swa armour and third core for the earth so export and also il have to run 10mm earth for the incoming water in the garage

 

[Larnacaman]

If you are bonding all the extraneous services within the building, with your SWA cable /core. ...Then you are ''Extending'' not Exporting!!!

 

[sparkattack]

sorry yeah thats what i ment. Is it ok to bond the incoming water to the consumer unit in the garage with 10mm and then use the swa and 3rd core as earthing back to house?

 

[Larnacaman]

That's exactly what i would do sparkattack, Certainly better than relying on a Rod!!

 

[sparkattack]

cheers. i know you dont know what current being drawn but would you use 10mm?

 

[androiduk2002]

Our local building control requires any out building more than 5mtrs away from main building to be TTed.

 

[Riggy]

Our local building control requires any out building more than 5mtrs away from main building to be TTed.

Building Control making the rules now? They didn't feel qualified to ensure compliance with Part P, hence the farce of self certification! headbang

 

[sparkattack]

back at the house i was going to use a swiched fuse box with a 60a fuse. Not sure on run exactly but i think its about 20m or so

 

[sparkattack]

doing calcuclations and might use 16mm swa to be safe on the 63a switched fuse and doesnt cost much more that the 10mm

 

[sparkattack]

as long as it is earthed obviously there is nothing wrong with using a metal consumer unit and isolating a supply supply into it using a suitable metal gland is there? i have no experience with metal consumer units

 

[SLIPSHOD & SLAPDASH]

Our local building control requires any out building more than 5mtrs away from main building to be TTed.

I find that statement very hard to believe. I would like to see documentary proof ?

---------- Post Auto-Merged at 22:48 ---------- Previous post was made at 22:44 ----------

as long as it is earthed obviously there is nothing wrong with using a metal consumer unit and isolating a supply supply into it using a suitable metal gland is there? i have no experience with metal consumer units

Not sure what your asking here. If you are using a Swa and its earth then a metal c/u is the way to do it ( and that sounds ok for this job) . If you are going to TT the system then you have to use an insulated enclosure before the Rcd.

 

[steptoe]

DNO make the decision if they will allow you to take the earth from a TNCS system outside the main building,

their answer will most likely NO , it covers their ass that way.