It is likely that the 16mm flat twin & cpc is capable of carrying the load current, however this cannot be confirmed unless the installed conditions are known.
If this cable is buried in a wall etc. at any point then it needs RCD protection, this then would put the whole house on a single RCD which falls foul of 314...
There is no reason that the garage CU cannot feed the house as long as this is done correctly and in accordance with regs.
The 6mm wire in the CU instead of a bus bar is a no no that is just dangerous really, 6mm 6491 is rated at best 47A, this is protected by what size overcurrent protective device, 60, 80, 100?
That is the DNO fuse.
Also, the consumer unit, unless designed & built by the contractor, will be a TTA or PTTA, I know that there are many that believe this situation is a pain, but, that is what we have to live with.
The garage consumer unit as installed does not comply with BSEN60439, unless it was manufacturer supplied with the 6mm sq linking wire, which if it is a small garage unit of 1 possibly 2 ways it could have been, however, in this case, I very much doubt it will have been designed to be located at the origin of the installation and carry such potentially high sub main currents, e.g. a whole house.
If the 6mm has been added by the installer then I would be amazed if the unit would meed the test described in 530.3.4.
Possibly an easy way to tell, is to check the wiring material used, if it's 6491 (to BS6004, or 7211) then it will almost certainly not have been fitted by the CU maker they would have used a Tri rated material to BS6231
IMHO
As it stands it falls foul of:
530.3.4
For an installation with a 230 V single-phase supply rated up to 100 A that is under the control of ordinary persons, switchgear and controlgear assemblies shall either comply with BS EN 60439-3 and Regulation 432.1 or be a consumer unit incorporating components and protective devices specified by the manufacturer complying with BS EN 60439-3, including the conditional short-circuit test described in Annex ZA of BS EN 60439-3.
432.1 Protection against both overload current and fault current
Except as permitted by Regulation 434.5.1, a device providing protection against both overload and fault current shall be capable of breaking, and for a circuit-breaker making, any overcurrent up to and including the maximum prospective fault current at the point where the device is installed.
434.5.1
Except where the following paragraph applies, the rated short-circuit breaking capacity of each
device shall be not less than the maximum prospective fault current at the point at which the device is installed.
A lower breaking capacity is permitted if another protective device or devices having the necessary rated short- circuit breaking capacity is installed on the supply side. In this situation, the characteristics of the devices shall be co-ordinated so that the energy let-through of these devices does not exceed that which can be withstood, without damage, by the device(s) on the load side.
NOTE: Technical data for the selection of protective devices can be requested from the manufacturer.
530.3.4 because I don't believe it is a TTA or PTTA and would not meet the requirements of the standard as it stands.
432.1 is included because it is referenced by 530.3.4
434.5.1 is included because it is referenced.
I also believe that it falls foul of:
523.1
The current, including any harmonic current, to be carried by any conductor for sustained periods during normal operation shall be such that the appropriate temperature limit specified in Table 52.1 is not exceeded. The value of current shall be selected in accordance with Regulation 523.2, or determined in accordance with Regulation 523.3
Because I believe the garage CU is not a standard device.
Also, it falls foul of:
511.1
Every item of equipment shall comply with the relevant requirements of the applicable British or Harmonized Standard, appropriate to the intended use of the equipment. The edition of the standard shall be the current edition, with those amendments pertaining at a date to be agreed by the parties to the contract concerned (see Appendix 1).
Alternatively, if equipment complying with a foreign national standard based on an IEC Standard is to be used, the designer or other person responsible for specifying the installation shall verify that any differences between that standard and the corresponding British or Harmonized Standard will not result in a lesser degree of safety than that afforded by compliance with the British or Harmonized Standard.
511.2
Where equipment to be used is not covered by a British or Harmonized Standard or is used outside the scope of its standard, the designer or other person responsible for specifying the installation shall confirm that the equipment provides at least the same degree of safety as that afforded by compliance with the Regulations.
Also anyone building a CU for use in an installation under BS7671 needs to comply with:
113 EQUIPMENT
113.1
The Regulations apply to items of electrical equipment only so far as selection and application of the equipment in the installation are concerned. The Regulations do not deal with requirements for the construction of assemblies of electrical equipment, which are required to comply with appropriate standards.
HTH!
If this cable is buried in a wall etc. at any point then it needs RCD protection, this then would put the whole house on a single RCD which falls foul of 314...
There is no reason that the garage CU cannot feed the house as long as this is done correctly and in accordance with regs.
The 6mm wire in the CU instead of a bus bar is a no no that is just dangerous really, 6mm 6491 is rated at best 47A, this is protected by what size overcurrent protective device, 60, 80, 100?
That is the DNO fuse.
Also, the consumer unit, unless designed & built by the contractor, will be a TTA or PTTA, I know that there are many that believe this situation is a pain, but, that is what we have to live with.
The garage consumer unit as installed does not comply with BSEN60439, unless it was manufacturer supplied with the 6mm sq linking wire, which if it is a small garage unit of 1 possibly 2 ways it could have been, however, in this case, I very much doubt it will have been designed to be located at the origin of the installation and carry such potentially high sub main currents, e.g. a whole house.
If the 6mm has been added by the installer then I would be amazed if the unit would meed the test described in 530.3.4.
Possibly an easy way to tell, is to check the wiring material used, if it's 6491 (to BS6004, or 7211) then it will almost certainly not have been fitted by the CU maker they would have used a Tri rated material to BS6231
IMHO
As it stands it falls foul of:
530.3.4
For an installation with a 230 V single-phase supply rated up to 100 A that is under the control of ordinary persons, switchgear and controlgear assemblies shall either comply with BS EN 60439-3 and Regulation 432.1 or be a consumer unit incorporating components and protective devices specified by the manufacturer complying with BS EN 60439-3, including the conditional short-circuit test described in Annex ZA of BS EN 60439-3.
432.1 Protection against both overload current and fault current
Except as permitted by Regulation 434.5.1, a device providing protection against both overload and fault current shall be capable of breaking, and for a circuit-breaker making, any overcurrent up to and including the maximum prospective fault current at the point where the device is installed.
434.5.1
Except where the following paragraph applies, the rated short-circuit breaking capacity of each
device shall be not less than the maximum prospective fault current at the point at which the device is installed.
A lower breaking capacity is permitted if another protective device or devices having the necessary rated short- circuit breaking capacity is installed on the supply side. In this situation, the characteristics of the devices shall be co-ordinated so that the energy let-through of these devices does not exceed that which can be withstood, without damage, by the device(s) on the load side.
NOTE: Technical data for the selection of protective devices can be requested from the manufacturer.
530.3.4 because I don't believe it is a TTA or PTTA and would not meet the requirements of the standard as it stands.
432.1 is included because it is referenced by 530.3.4
434.5.1 is included because it is referenced.
I also believe that it falls foul of:
523.1
The current, including any harmonic current, to be carried by any conductor for sustained periods during normal operation shall be such that the appropriate temperature limit specified in Table 52.1 is not exceeded. The value of current shall be selected in accordance with Regulation 523.2, or determined in accordance with Regulation 523.3
Because I believe the garage CU is not a standard device.
Also, it falls foul of:
511.1
Every item of equipment shall comply with the relevant requirements of the applicable British or Harmonized Standard, appropriate to the intended use of the equipment. The edition of the standard shall be the current edition, with those amendments pertaining at a date to be agreed by the parties to the contract concerned (see Appendix 1).
Alternatively, if equipment complying with a foreign national standard based on an IEC Standard is to be used, the designer or other person responsible for specifying the installation shall verify that any differences between that standard and the corresponding British or Harmonized Standard will not result in a lesser degree of safety than that afforded by compliance with the British or Harmonized Standard.
511.2
Where equipment to be used is not covered by a British or Harmonized Standard or is used outside the scope of its standard, the designer or other person responsible for specifying the installation shall confirm that the equipment provides at least the same degree of safety as that afforded by compliance with the Regulations.
Also anyone building a CU for use in an installation under BS7671 needs to comply with:
113 EQUIPMENT
113.1
The Regulations apply to items of electrical equipment only so far as selection and application of the equipment in the installation are concerned. The Regulations do not deal with requirements for the construction of assemblies of electrical equipment, which are required to comply with appropriate standards.
HTH!
