Main Switch And Rcd Wrong Way Round

[maffematics]

Hi All

I carried out a domestic condition report today on a very small cattery and was wanting to know if the main switch and RCD were the wrong way round or even if it matters

It is a domestic property with a wooden shed in the garden being used as an cattery. The incoming supply is an TNCS system which supplies a 40A RCD using 25mm Tails and a 16mm earth which then supply a 10mm 3 core armoured cable which goes to the cattery into a 4x4 enclosure where the earth cable stops and the live conductors go into the metal clad consumer unit connecting to into the 100 main switch. An earth rod as been installed bringing an 16mm earth cable into the consumer unit as the main earth.

Would it be better to have the 100A main switch on the TNCS supply and the RCD on the TT supply or doesn't it make any difference

Thanks in advance

Matt

 

[ProDave]

Your description leaves out a lot of detail, like how is the rest of the house fed? does the feed to the cattery come off the same RCD as the rest of the house (I would hope not being only rated at 40A)? 

If it's just an rcd henley blocked into the tails to feed the SWA to the cattery then I would not be happy as there's no OCPD for the SWA (apart form the suppliers probably 100A fuse)

Are you sure it's not a 40A / 30ma rcbo?

If it is the same rcd that feeds the whole house then it's an even lot more wrong, not least because a 40A rated RCD is inadequate.

A bit more detail please?

 

[Andy™]

clearly way out of your depth with this...

so the cable is only protected by a 40A RCD? in which case, surely the fact its got no OCPD should be of concern

and as you should already know, if you have a TT system, then you cannot have a metal enclosure unless the is an RCD fitted before the enclosure, or other suitable precautions are taken... so a very good reason for the RCD being where it is...

 

[MajorOak]

You should send some images in of the installation. 

 

[maffematics]

hi a bit more detail

Suppliers fuse is 80A and the meter tails are Henley blocked the above stated RCD is a 30mA RCBO feeding the swa the armouring is earthed via tncs supply but is not entering the metal consumer unit hope this make it a bit more clear

Thanks for your input

Matt

 

[OnOff]

hi a bit more detail

Suppliers fuse is 80A and the meter tails are Henley blocked the above stated RCD is a 30mA RCBO feeding the swa the armouring is earthed via tncs supply but is not entering the metal consumer unit hope this make it a bit more clear

Thanks for your input

Matt

Erm.........an RCD is NOT an RCBO. 

 

[maffematics]

I stated in my first post that an RCD was protecting the SWA but it is a RCBO That is protecting the SWA

 

[Andy™]

so you ask a question without supplying all the details, and getting the basics wrong... so it looks like i was probably correct with my reasoning for it, along with the person who installed it that way. so do you now need to get back and give them a satisfactory report after giving this setup a C1?

 

[apprentice87]

If you do not know the basic requirements for earthing arrangements off the top of your head for the various types of earthing systems, you should not be doing EICR's...

john...

 

[Sidewinder]

Is it a 2 pole RCBO?

If not then you will have other issues on a TT.

Does it need to be 30mA?

Does it need an RCD?

More questions to come, and as has been said, pictures would be useful.