switch fuse for meter tails

[jstephens251]

Hi everyone,

i have a job where the tails from the meter box are protected by a 1361 type 2 fuse then onto a dp main switch then about 5 mts to consumer unit. tails need moving to a more suitable position and probably have to be extended. I've seen quite a few posts which say anything over 3 mts
require a switch fuse? where is this in the regs?
what would be best practice here, dp switch into 80a kmf then onto consumer unit?

cheers

 

[IQ Electrical]

Hi everyone,

i have a job where the tails from the meter box are protected by a 1361 type 2 fuse then onto a dp main switch then about 5 mts to consumer unit. tails need moving to a more suitable position and probably have to be extended. I've seen quite a few posts which say anything over 3 mts
require a switch fuse? where is this in the regs?
what would be best practice here, dp switch into 80a kmf then onto consumer unit?

cheers

It's not a BS7671 requirement, it's a DNO requirement and as such, can vary around the country, we've had from 2.5M right up to 4M quoted at various locations.

Double pole 80A switch-fuse will cover most eventualities.

 

[Dic Penderyn]

[FONT=&quot]The DNO can certainly restrict on the length of the meter tails, sometimes as little as 1m or 2m metres at the origin of the supply. [/FONT]
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[FONT=&quot]However, when the Distribution Board, switchboard or Consumer Unit are positioned away from the origin of the supply and the tails are over the maximum length given by the DNO. An extra link switch or circuit breaker can be installed which will act has a main switch. As required by 537.1.4 this main switch (link switch) will be best positioned as near to the origin of supply as practicable.
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[FONT=&quot]Remember that the DNO do not permit you to install this switch on their meter board.[/FONT]
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[FONT=&quot]Considering regulations 433.3.1(iii) and 434.3(iv) with regards to the omission of [/FONT][FONT=&quot]Protection against overload current and fault current. The DNO might ask you to meet the following:[/FONT][FONT=&quot][/FONT]
· [FONT=&quot]restrictions on the type and length of the meter tails,[/FONT]
· [FONT=&quot]the minimum cross-sectional area for the meter tails, and[/FONT]
· [FONT=&quot]the minimum cross-sectional area for the earthing conductor.[/FONT]
· [FONT=&quot] [/FONT]
[FONT=&quot]In some cases the DNO install mains breakers after the meter as a means of isolation for the consumer. Therefore would it not seem pointless to install another switch or breaker next to the one installed by the DNO without considering the above or inquiring about using the cut-out as your [/FONT][FONT=&quot]Protection against overload current and fault current?[/FONT]

 

[jstephens251]

thanks for replys a call to the DNO probably the best move then. This installation was only rewired in October and the electrician has only installed a 100a dp main switch which is what made me think if more was needed with the length of tails probably going over 5 mts

cheers