Is this acceptable

[ubrian]

An electrician had to install a new electrical supply to air conditioning condensors
and internal cassette
2 no 30 A supplies
1 no 10 A supply to internal unit

Instead of running these from the incoming mains board they did the following

They installed a new consumer unit along side an existing consumer unit
This ex consumer unit was some 15 m away from incoming mains and supplied by a 6 mm twin and earth cable
The new consumer unit was connected into ex consumer unit with 16 mm tails

The installation operated ok until recently

The neutral tail became loose and started arcing

I believe the 16 mm tails were connected to the same terminal as the 6 mm twin and earth

Was this installation within the regulations
Would this installation be considered "good practice"
The original works were carried out in 2006

 

[ubrian]

The ex consumer unit was fused at 32 A

 

[ubrian]

The ex consumer unit was feeding a 7litre water heater and a double socket and three fluorescent lights

The cable to the condensor units was 16 mm

The 32 A fuse had never tripped over the four year period

 

[Deleted member 9648]

An electrician had to install a new electrical supply to air conditioning condensors
and internal cassette
2 no 30 A supplies
1 no 10 A supply to internal unit

Instead of running these from the incoming mains board they did the following

They installed a new consumer unit along side an existing consumer unit
This ex consumer unit was some 15 m away from incoming mains and supplied by a 6 mm twin and earth cableIn that case the max load on this CU would be around 30-40 a
The new consumer unit was connected into ex consumer unit with 16 mm tails

The installation operated ok until recently

The neutral tail became loose and started arcing

I believe the 16 mm tails were connected to the same terminal as the 6 mm twin and earth

Was this installation within the regulations
Would this installation be considered "good practice"
The original works were carried out in 2006...No and no...clearly the existing arrangements would not be adequate for the additional load,this is a fundamental requirement of additions to an existing installation

.........

 

[Deleted member 9648]

The ex consumer unit was fused at 32 A

That would be acceptable for the 6.0mm T/E supply cable

 

[Deleted member 9648]

The ex consumer unit was feeding a 7litre water heater and a double socket and three fluorescent lights

The cable to the condensor units was 16 mm

The 32 A fuse had never tripped over the four year period

If the 32a protective device has not tripped over a 4 year period that would suggest that the DB was not overloaded as suggested in the OP....what is the running load on the A/C units?............
That said based on the info in the OP it still sounds like the existing CU is not up to running the additional loads.

 

[ubrian]

The running load for the cassette units would be about 6 A each
and 3 A for the internal unit