Discrimation...

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DonkeyDong

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Heres one for a Friday night... :D

How do you guys deal with discrimation of RCDs with the 17th?

Previously Type S/Time delayed were quite popular, but you dont hear a mention of them now...

So for an example you might find in a domestic, you have a garage or out building which is fed from the house CU/DB. The circuit to the garage is RCD'ed due to cable depth/type (thanks 17th Ed). This runs to the shed which has a mini CU/DB with RCD - how do you achieve discrimation ?

Do you either not fit an RCD in the shed, or fit a Type S in the house (bearing in mind you can't get Type S RCBO's for domestic boards)

D.

 

steptoe

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Heres one for a Friday night... :D How do you guys deal with discrimation of RCDs with the 17th?

Previously Type S/Time delayed were quite popular, but you dont hear a mention of them now...

So for an example you might find in a domestic, you have a garage or out building which is fed from the house CU/DB. The circuit to the garage is RCD'ed due to cable depth/type (thanks 17th Ed). This runs to the shed which has a mini CU/DB with RCD - how do you achieve discrimation ?

Do you either not fit an RCD in the shed, or fit a Type S in the house (bearing in mind you can't get Type S RCBO's for domestic boards)

D.
apart from the fact that cant doesnt really exist apart from in the vocabulary of people that really mean to say they cant be bothered,

I think you should try different wholesalers.

 

Admin1

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I'd go along with KME on this one.

 

Mr Sworld

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Heres one for a Friday night... :D How do you guys deal with discrimation of RCDs with the 17th?

Previously Type S/Time delayed were quite popular, but you dont hear a mention of them now...
Time delay RCD's are still very common in industrial situations as well as 100mA, 300mA and 500mA RCD's.

 

DonkeyDong

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Forgive my ignorance.. :(

Can you please give me links to, or part numbers of Crabtree 30ma Type S RCBOs? Or MK or Wylex? I have looked and cant find them??

D.

 

DonkeyDong

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Steptoe and mr sword - have either of you managed to find me the part numbers for a crabtree, or mk, or wylex type s 30ma rcbo yet?

I could do with tracking them down.

Many thanks,

D.

 

steptoe

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Steptoe and mr sword - have either of you managed to find me the part numbers for a crabtree, or mk, or wylex type s 30ma rcbo yet? I could do with tracking them down.

Many thanks,

D.
sorry buddy, too much like actually doing something, I simply go to wholesalers and tell them what I want by next week, not always the correct sort but if it fits Im generally happy enough, I use hager quite a lot on 3ph and seems ok.

but your prob right about not easy to find, f uck ing UK regs to blame methinks.

 
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Heres one for a Friday night... :D Previously Type S/Time delayed were quite popular, but you dont hear a mention of them now....
No longer required for TT systems hence not so available

.

So for an example you might find in a domestic, you have a garage or out building which is fed from the house CU/DB. The circuit to the garage is RCD'ed due to cable depth/type (thanks 17th Ed). This runs to the shed which has a mini CU/DB with RCD - how do you achieve discrimation ?.
Move circuit to non-rcd side of board and fit standalone RCD or RCBO, or change CU

 
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You can't fit a time delayed RCD as you propose and still stay within the 17th regs.The only way you could have any discrimination is to have a smaller rcd tripping current at the load end. Steptoe will now get on his soap box and shout that the regs are a guide. Listen to him if you wish but only a 30mA rcd at the feed will suffice.

 

steptoe

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You can't fit a time delayed RCD as you propose and still stay within the 17th regs.The only way you could have any discrimination is to have a smaller rcd tripping current at the load end. Steptoe will now get on his soap box and shout that the regs are a guide. Listen to him if you wish but only a 30mA rcd at the feed will suffice.
NO I wont, TBH its got a lot to do with the situation, and believe it or not in most domestic I will usually always stick to the regs, NA NA NA NAAA NA. :p

your prob very right about discrimination in 17th, suppose thats why we have to use high integrity boards and RCBOs so much now, :(

 
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