What maximum amperage for cables

[clez50]

This question has probably been asked several time but things change. The house I'm living in now was built in the 1960's and has a ring main using 4mm Flat Twin and Earth. A lot of properties I've noticed have been wired with 2.5mm FTE and both connected through originally a 30amp fuse or more lately a 32amp mcb. My question is what's the maximum amperage that each size of cable can carry?

 

[IAmSparkytus!]

All depends on length of runs and how they’ve been installed

 

[mainline]

This question has probably been asked several time but things change. The house I'm living in now was built in the 1960's and has a ring main using 4mm Flat Twin and Earth. A lot of properties I've noticed have been wired with 2.5mm FTE and both connected through originally a 30amp fuse or more lately a 32amp mcb. My question is what's the maximum amperage that each size of cable can carry?

Is this cable stranded or solid ?

 

[MDJ]

Is this cable stranded or solid ?

I would say Solid

 

[brianmoooore]

If the wiring dates from the '60s, I doubt if millimetres comes into its size.
Is the metal comprising the wires copper or silver coloured?

 

[clez50]

Is this cable stranded or solid ?

Hi the 4mm is stranded.

 

[clez50]

If the wiring dates from the '60s, I doubt if millimetres comes into its size.
Is the metal comprising the wires copper or silver coloured?

Copper

 

[Taylortwocities]

and has a ring main using 4mm Flat Twin and Earth

Are you sure it is a RING? It's more likely to be a radial circuit.

 

[clez50]

Are you sure it is a RING? It's more likely to be a radial circuit.

No mate, definitely a ring circuit.

 

[oracle]

Installation method?

 

[DefyG]

It may have been designed that way to meet volt drop, R1+R2 values etc based on using a 30A OCD?
4mm will under right circumstances allow greater ccc than 30A but that’s not a reason to exceed the current OCD.

 

[davesparks]

The house I'm living in now was built in the 1960's and has a ring main using 4mm Flat Twin and Earth.

How old is this cable, could you post up a picture of it?
At that age it may be imperial sized cable which was physically bigger and the equivalent of modern 2.5mm is physically the same size as modern 4mm

 

[brianmoooore]

How old is this cable, could you post up a picture of it?
At that age it may be imperial sized cable which was physically bigger and the equivalent of modern 2.5mm is physically the same size as modern 4mm

He says it's copper coloured, so that suggests metric, in which case it wasn't made in the sixties.

 

[Taylortwocities]

No mate, definitely a ring circuit.

So there are two conductors in the top of the MCB?

 

[westward10]

From that period could easily be copper clad aluminium as the used sizes were 1.5 solid and 4.0 stranded or nearest imperial equivalent.

 

[davesparks]

He says it's copper coloured, so that suggests metric, in which case it wasn't made in the sixties.

Suggests yes, but doesn't prove it, not all imperial cables were tinned.