17th Can someone help

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ElectekAir

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Hi All

Just looked at a job, install supply to a garage and workshop, need to upgrade supply to the hot tub so some sockets can be put outside.

The question is under the new 17th is it nessasary to replace the old 16th split load board

Any suggestions will be helpfull

Craig

 

Theorysparky

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Hiya

no you dont

as long as the new cicuits you install comply with the 17th

when you work out how you are going to do it post it here and we shall have look

we are all on the learning curve at the moment with the 17th

so healthy discussion is good :)

 

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Hi AllJust looked at a job, install supply to a garage and workshop, need to upgrade supply to the hot tub so some sockets can be put outside.

The question is under the new 17th is it necessary to replace the old 16th split load board

Any suggestions will be helpfull

Craig
Are you addin a new circuit or modifying an existing one?

If adding: have you got a spare slot on the RCD side of the split load board?? is yes you is laughing! :)

If modify: is existing circuit already RCD protected?? if yes you is laughing! :)

If NON RCD or no spare RCD protected spare ways in the CU then you probably need an RCBO. :|

(stick and extra

 

ElectekAir

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Ok here goes..

The circuit in question is for a sub board, the supply cable is however too small for the new works so the cable will be changed. There is a space on the RCD side of the old CU to put the new cable for the sub board into.

The new cable will then run from this sub board into the garage 60m away from the house and feed a new CU in the garage a seperate bulding is going to be constructed behind the garage 2m away and will be a new home office.

So then from main CU to Sub1 then from Sub1 in garage to Sub2 in office

does this make sense...

the original supply to the sub was a 4mm ( this sub supplies a hot tub and some new sockets, the sub also has a 40A 30ma RCBO )

proposing a new 16mm SWA from Main board to sub board then a 10mm SWA from sub board to Sub1 and a 6mm SWA to Sub2

But am concearned coz there will be a RCD in the main board supplying a RCD in Sub board as well As RCD in Sub1 and Sub2 (to try and conform to new regs) i feel that there will be a problem with this as 1 RCD suplying anouther is just asking for nusiance tripping...

Any sugestions

Craig

 

Flying Scotsman

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you only need the rcd once on the circuit putting two or more will cause the rcds to talk/chatter :^O (''hello rcd 1 how are you this fine morning?, Hello RCD2 i am very well thankyou hows about you? im very well too thanks for asking rcd 1, what are you up to today then? well i thought i would go shopping this fine day.! ) :^O :^O:^O:^O:^O

seriously though if more than 1 rcd is on the circuit then the chances of nuisance tripping is quite a high possiblity. So my advice is change all other borads to a main switch only and mcbs and put the suppply side from the origin ie from the c/u in the house on the rcd.

hope that makes sense ?:| :|

 

Theorysparky

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you only need the rcd once on the circuit putting two or more will cause the rcds to talk/chatter :^O (''hello rcd 1 how are you this fine morning?, Hello RCD2 i am very well thankyou hows about you? im very well too thanks for asking rcd 1, what are you up to today then? well i thought i would go shopping this fine day.! ) :^O :^O:^O:^O:^Oseriously though if more than 1 rcd is on the circuit then the chances of nuisance tripping is quite a high possiblity. So my advice is change all other borads to a main switch only and mcbs and put the suppply side from the origin ie from the c/u in the house on the rcd.

hope that makes sense ?:| :|
or to put it another way

sub 1 has the rcd all the rest are main switches

or

could it be possible (expensive i know) to have sub 2 rcd sub 1 with rcbo's

that way if the tub trips you dont lose the garage ???

 

Theorysparky

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i still say rcd main cu then sub and sub 2 main switch;)
if you do that then ,,if the tub causes a trip then you lose the rcd side of the house ???

or have i missed where you are going to have the rcd

house or sub1:)

 

seajayess

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If the supply to the sub boards is going to be in SWA all the way change the RCBO for a 40 A MCB then there is no need to RCD protect the cable, You could then fit RCD's in the relavent CU where they are placed, ie garage / office, so you will eliminate nuisense tripping at the supply dont forget you will proberbly have to provide an earth stake and make the sub boards TT hope this helps CJS

 

ElectekAir

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If the supply to the sub boards is going to be in SWA all the way change the RCBO for a 40 A MCB then there is no need to RCD protect the cable, You could then fit RCD's in the relavent CU where they are placed, ie garage / office, so you will eliminate nuisense tripping at the supply dont forget you will proberbly have to provide an earth stake and make the sub boards TT hope this helps CJS
Now i'm stupid why the spike, all the SWA will be 3core

Craig

 

seajayess

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Because you have taken the supply out side the equipotential zone so you will have to make it TT, unless it is already TT then adding another stake will be OK CJS Disconection time will be 5 seconds :D

 

steptoe

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u CANT export the earth, see other posts.....

also I think you will have to upgrade the board, if you install, change a circuit you have to make sure it wont cause a nuisance to other circuits by tripping out,

ie, if your circuit trips you have to be sure nothing else important will trip along with it,

if you only have one RCD you will have to fit a second one.

BTW, I reasonable think to totally comply we need 3 RCD boards,

cooker, kitchen sockets, and downstairs lights, +++(heat detector,fridge,wash machine,need i go on?)

so if one trips the other two(or more) dont,,,,,,,

 
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Hello all

I have got a little confused with this thread.

But the way I see it. I would put a new seperate switch fuse in to feed this supply house end direct of mains and depending on load ie if hot tub is still to be used you may need 60 amp supply. As long as it is either tns or tncs house end no rcd protection would be needed. If it is tt house end then a time delay rcd would be needed this end. As said by others sub boards garage end would need to be made tt anyhow.

batty

 

kme

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If you`ve got a split board, then it shouldn`t be TT. I`d MCB from the non-RCD side, then main switch at the subs. As noted prior - don`t export earth. Therefore the subs are TT; and must have protection; esp. as we haven`t provided at house. 30mA would be a requirement at sub1; therefore would not be necessary at sub2.

in my opinion.

KME

 
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Agreed kme

Although I recently had a standard main switch split load board on tt system. Ended up putting in new earth rod and time delay rcd in enclosure before consumer unit to protect no rcd ways. Cheap option for customer as was before 17th edition.

batty

 
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