safety device for distribution circuit!

[bluesky]

just visited a house, 3 phase supply, there is a swimming pool in the back garden, the thing worries me is there is only a cut out fuse for the SWA distribution cable, no safety device,cable is about 20m long underground to the shed, what is the best safety device shall i persuade the owner to use, a 100A RCD?

cheers

 

[Deleted member 9648]

Will need a means of isolation and fault/overcurrent protection...whether an RCD is required for the distribution circuit would depend on the earthing system. Much more info needed....such as size of SWA,loading,earthing system,provision of RCD'S at the pool end?

 

[Dunc]

When you say 'a cut out fuse', do you mean the 100A BS1361 (or similar size fuse) that is in the suppliers service head or one of these?

LINK

Probably misunderstanding what you mean at the moment so don't want to comment too much.

 

[IQ Electrical]

just visited a house, 3 phase supply, there is a swimming pool in the back garden, the thing worries me is there is only a cut out fuse for the SWA distribution cable, no safety device,cable is about 20m long underground to the shed, what is the best safety device shall i persuade the owner to use, a 100A RCD?

cheers

I think you'll need to provide a bit more information then that.

Why does the mechanically protected SWA need rcd protection?

Is there rcd protection in the 'shed'?

What is the earthing system?

Is this supplying the pool plant?

Is the 'cut out fuse' the DNO fuse or in effect, a distribution circuit protective device?

 

[mart8235]

RCD is not required on a distribution circuit.
an earthed SWA should be used and this is all you would need.
IF the house is on a tt system then there should/could be a 100mA RCD protecting the whole installation. thats the only requirment.
it doesn't matter if its a BS 60898/3871/88..... thats your protection!! your disconection time is 5sec (if tn system) for distribution so just cjeck yor cable size ect.

 

[IQ Electrical]

RCD is not required on a distribution circuit.
an earthed SWA should be used and this is all you would need.
if the house is on a tt system then there must be a 100mA RCD protecting the whole installation. thats the only requirment.
it doesn't matter if its a BS 60898/3871/88..... thats your protection!! your disconection time is 5sec for distribution so just cjeck yor cable size ect.

Can you point me to that regulation please?

In a '17th edition' consumer unit why would you use a 100mA RCD?

 

[bluesky]

hi, yes there is a 100A switch in a steel box in the main house, 16mm2 distribution cable, 20m away in the shed there is a box which has main switch, 80 RCD and circuits for swimming pool heater, sockets and lights, it is tn-s system, i am thinking what if the SWA get disturbed sometimes such as a spade? without circuite breaker or rcd, then the power wont be off

 

[IQ Electrical]

hi, yes there is a 100A switch in a steel box in the main house, 16mm2 distribution cable, 20m away in the shed there is a box which has main switch, 80 RCD and circuits for swimming pool, sockets and lights, it is tn-s system, i am thinking what if the SWA get disturbed sometimes such as a spade? without circuite breaker or rcd, then the power wont be off

That's why you install mechanically protected cable at a suitable depth with identification tape/tiles.

 

[bluesky]

That's why you install mechanically protected cable at a suitable depth with identification tape/tiles.

hi IQ Electrical, you are right, but i see a lot of garden work going on there, i dont know the depth and how the SWA cable runs, but bit not sure if steel net can protect the cable from sharp spade...

 

[IQ Electrical]

Is this a periodic inspection?

 

[bluesky]

Is this a periodic inspection?

no, just changed a bulb in the shed...

 

[nickblake]

RCD is not required on a distribution circuit.
an earthed SWA should be used and this is all you would need.
if the house is on a tt system then there must be a 100mA RCD protecting the whole installation. thats the only requirment.
it doesn't matter if its a BS 60898/3871/88..... thats your protection!! your disconection time is 5sec for distribution so just cjeck yor cable size ect.

Im with IQ on this one you cant say that the disconnection time is 5 seconds as you dont know the size of the protective device !!! all circuits up to 32 amps have a disconnection time of 0.4 seconds ,above 32 amps is 5 seconds , and again if you have a 17th addition board installed as IQ has stated there is no need for a 100ma RCD

 

[IQ Electrical]

no, just changed a bulb in the shed...

No way!

Change the 'bulb' then and get him to call you if he ever digs through the SWA !!

 

[bluesky]

hi nickblake, do you agree with mart that SWA is enough with distribution cable, as long as there is 17th edition board in the shed?

 

[bluesky]

No way!

Change the 'bulb' then and get him to call you if he ever digs through the SWA !!

just had a quick look of the wiring in the main house, it is really not my responsibility if someone digs through the SWA...