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Splitting A Incoming Supply???


mattmoonman

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mattmoonman

Hello gentlemen....My first post....So Be gentle!!!

Firstly if there are any old threads that could help me with the below issues, if someone could point me in the right direction that would be great or if I

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10 answers to this question

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The Godfather
Hello gentlemen....My first post....So Be gentle!!!

Firstly, welcome:

Secondly, we don't have it any other way here.

Don & His Boys

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SPECIAL LOCATION
Hello gentlemen....My first post....So Be gentle!!!

Firstly if there are any old threads that could help me with the below issues, if someone could point me in the right direction that would be great or if I

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green-hornet

Regulations for electric and gas mains seperation is 150mm.

Although when routing within the home a seperation of 50mm is for some reason acceptable.

100mA rcd's are normally used on TT installations.

Or where discrimination is required.Where type S could be used.

Swa supply cable would not require any rcd protection and could be used to supply a sub main.

We would need more information to give you any detailed advise, as we can only guess at what type of installation you are asking about.

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mattmoonman

Right firstly is not a TT system it a TN-C-S system and secondly the Type S 80A RCD 100mA, is i through a way of discriminating between the downstream RCD in the Annex CU. Can you get a S Type 30mA RCD???

The granny annex is physically joined to the existing property and is single story .The routing of the 16mm cable would be through the existing built and then dropping down into the annex.

80A fused Switched and then use 16mm SWA to annex ...No RCD sound like a good option. I was looking at going outside and around the house to the Annex with SWA at one point Using a Henley block to a 100 DP Isolator (switch gear) I just didn

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green-hornet

You are right s type is me talking out of my posteria as it refers only to the mcb and not rcd.

For any discrimination you would have to use a higher mA than downsteam, it is easier to get the 80mA than the 100mA in my experiance.

Where discrimination is required I always try to get the 80mA rcd or use swa, depending on if rcd protection is required.

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SPECIAL LOCATION

TN-C-S submain, why RCDing?...

If not buried in fabric of building, it wouldn't need RCD protection.

just overload protection if greater than 3m length.

joined building.. no probs associated with the ole "exporting" issue!;):|

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mattmoonman

Thanks for all your comments guys... And for your info the submain will be buried in the building and so can not be surface run..

Cheers Moonman

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Robin Spark

So if SWA is to be buried in fabric of building then use SWA ( 16mm 3 core) then no hassle with rcd's, split tails at main cutout with henleys and use appropriatell fused switch fuse enclosure ie something like wylex do.

Ps dont think taking supply off existing CU is best idea

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Evans Electric
You are right s type is me talking out of my posteria as it refers only to the mcb and not rcd.

For any discrimination you would have to use a higher mA than downsteam, it is easier to get the 80mA than the 100mA in my experiance.

Where discrimination is required I always try to get the 80mA rcd or use swa, depending on if rcd protection is required.

Have you noticed , even when The Hornet is talking out of his ass , somehow it still makes sense, wish I could do that. All I can manage is a rasping noise or high pitched squeak !!! :coat

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You are right s type is me talking out of my posteria as it refers only to the mcb and not rcd.

For any discrimination you would have to use a higher mA than downsteam, it is easier to get the 80mA than the 100mA in my experience.

Where discrimination is required I always try to get the 80mA rcd or use swa, depending on if rcd protection is required.

Never seen a 80ma rcd are you sure you are not meaning 80 amp

also a 100ma rcd could trip faster than a 30ma it all depends on the fault current if the fault current is above 100ma both rcd will see this and could trip,so a S type is the only way to go.

as already said if the submain cable is surface run no rcd is required

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