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Posted By Topic: Combined Meter/MSB

chau428
Apr 08 2018 19:45

Have a new domestic build coming up and the garage is closest to the road. House is external to the garage. I\'m not doing the builders temp, but the Temp builders supply will be a combined meter and MSB during the build with earth stake inspected. Owner looking at transfering this into the garage (and will leave enough cable to transfer the temp supply into the garage and make it permanent) without the need to break any meter seals but will change the MEC to buried thus will need another inspection. Looking at whether it is better to leave the configuration as a combined meter/MSB located inside the garage and run a submain to the house or have the Meter only in the garage and have the MsB inside the house.

If the Garage does become a combined Meter/MSB, can I run a 16mm Single core neutral screen with a separate 6mm Earth (as specified in Table 5.1) inside conduit buired underground to the distribution board inside the house? Or will I need to run 16mm 2C+e (as a single sheath cable) to the DB? Couldn\'t find anything in the std which prohibits me in running a separte earth with basic insulation as a submain earth.

I know that there is also the general rule of thumb of 2 degrees of separation for discrimation, thus if the Mains fuse is 63A, then my submain fuse to the house will be 40A which is most likely not enough for the house.

Argh....

   

AlecK
Apr 08 2018 19:49

luckily for you - and lots of others who haven\'t even thought about it - discrimination is not absolutely required at these current revels.
   

pluto
Apr 08 2018 20:08

Why not usde a buried 25 mm2 copper cable as a horizontal earth electrode in the consumer mains trench, it will not get damged during building operations.

I would recommend a main switchboard in the garage to fed a submain to the nternal distribution switchboard and the electric vehicle charging point in the garage.

Depending of supply sourcve for the hot water system thay may require another core in the submain cable.
   

chau428
Apr 08 2018 20:44

Thanks for the thoughts, Yes, it will be an electric 3kw HWC so will need to run another cable in the submain into a double pole isolator in the DB. Thanks for advice re discrimination. I know its a should rather than a shall at this current level. Cheers