mcb and cable

[geezer]

1.5 t&e , whats the highest rating cb it can take in normal wiring conditions no insulation?

 

[jondiy]

I think the cable can take about 18 amps, but you will have to check. In that case a 16 amp mcb would do it, but personally I'd put it on a 10 amp as its primarily used for heavier lighting loads (or as a spur load cable).

Depends what purpose you are using it for.

 

[RF Lighting]

Personally I wouldn't connect 1.5mm2 to an MCB rated above 10 amps. Others may argue otherwise. With no derating factors 1.5mm2 is rated at 19.5 amps, but this is an absoloute maximum and must be derated for other factors such as ambient temperature, if it is connected to a rewireable fuse, any grouping factors, if it is run in trunking or conduit etc.

I would wait to see what the consensus is from some of the other guys in this forum.

 

[Spark123]

I don't think you'll get very far with the 1.5mm² on a 16A load/breaker before volt drop/efli become an issue, personally I don't think I'd consider using it on a circuit over 10A either.

 

[PompeySparks]

I totally agree RF Lighting

Any circuits over 10A I would wire in at least 2.5mm. BS7671 gives 1.5mm buried in plaster 14A! Admittedly, you could JUST get away with a 16A breaker if the circuit is all in trunking (alone) or clipped direct but Spark123 has highlighted the possible problems with this!

Good advice guys!

 

[Pensdown]

1.5 t&e , whats the highest rating cb it can take in normal wiring conditions no insulation?

Just out of interest, did you have a specific requirement?

 

[Steve]

Just out of interest, did you have a specific requirement?

10.8kw shower circuit.







these pesky DIYers

 

[RF Lighting]

 

[Spark123]

Just out of interest, did you have a specific requirement?

10.8kw shower circuit.







these pesky DIYers

Does this include underfloor heating?

 

[Steve]

Just out of interest, did you have a specific requirement?

10.8kw shower circuit.







these pesky DIYers

Does this include underfloor heating?

dont be silly, that needs 2.5mm² cable at least!

 

[geezer]

Just out of interest, did you have a specific requirement?

:

yes 2 existing 6amp cb circuits , put new lights on these circuits , chandeliers and a good increase in the wattage, so was thunking if the circuits might require a higher cb to help with the load , but i think that the two circuits are coping, likewise i would not go any higher than a 10amp cb after taking diversity in to account. thanks for the input from all!

 

[kai]

1.5.sq.mm. cable can safely take 13amps loading, as it can safely be used to feed socket outlets from fused spurs fed of a 13amp fuse-connection unit.
See the onsite guide - it states that 1.5.sq.mm. cable is an allowable size on a 13amp fused spur off a ring final circuit.

 

[Spark123]

Please remember you still need to take efli and volt drop into consideration when doing this, for a 10A type B MCB the max efli is 3.84ohms measured at 10degC for a 70 degC cable.
Volt drop is given for 1.5mm² flat twin+earth cable by (29 x design current x length)/1000, max 9.6v.

 

[RF Lighting]

1.5.sq.mm. cable can safely take 13amps loading, as it can safely be used to feed socket outlets from fused spurs fed of a 13amp fuse-connection unit.
See the onsite guide - it states that 1.5.sq.mm. cable is an allowable size on a 13amp fused spur off a ring final circuit.

I would personally use 2.5mm2 in this situation, For the difference in price etc. it is daft to use a smaller cable. What happens in the future when an extra socket is required and someone tries to install it themselves? Rewire it in 2.5mm2? Or just slap another socket on the end and hope it will 'be rite'?

Rob