Which Reg in the Yellow book

[tony mc]

Reg 433.1.204
Is in relation to Accessories to BS 1363 supplied through a Ring Final circuit etc and Appendix 15 gives Ring and Radial circuit arrangements.

The minimum CSA is 2.5 mm (1.5 MI ) unless a FCU is used and it can be reduced!

Just been asked to find the Reg which states 1.5mm CSA cable cant be used as a radial which has a 16A mcb on the circuit with 3 doulbe socket outlets connected.

Think I am looking too hard!

Thanks

 

[Deleted member 26818]

There isn't one.
Table 52.3 give the minimum CSA for power circuits, which is 1.5mm if copper.

 

[tony mc]

Thanks Spin I will have a look at that

 

[Spoon]

Doesn't it depend on what installation method you are using and what load characteristics?

 

[tony mc]

Cant find a Thanks Icon

 

[tony mc]

Thanks Spoon I looked at Appendix 15 but this is a cct direct from the CU on a 16A mcb I will have a look at table 52.3

 

[Midwest]

OP it depends on the design of the circuit, load & method of installation. The use of an FCU on a RFC to supply further sockets etc (appendix 15), relies on the fact that the maximum fuse (manufactured) for load side of the FCU is 13amp. Table 4D5 (insulated & sheathed flat cable) has various ccc for 1.5mm dependant on method on installation.

6242y 1.5mm could be fed via a 16mcb at CU, dependant on type of load, method of installation and consideration of volt drop. Personally, in these circumstances I would consider 2.5mm as a minimum, as demonstrated in Appendix 15.

 

[Deleted member 26818]

When designing circuits, you must ensure the CCC of conductors is greater than the rating of any OverCurrent Protective Devices.
With an RFC this is achieved because the two legs of the ring are in effect parallel conductors. It is the combined CCC of the two legs which is greater than the rating of the OCPD.
With a standard RFC protected by a 30/32A OCPD, all conductors and accessories must be rated at a minimum of 20A. Spurs are allowed using 20A conductors if they feed a single accessory, as the accessory is also rated at 20A.
Where a spur is intended to supply two or more accessories, then either overcurrent protection must be provided such as by use of an FCU, or conductors with a CCC greater than the OCPD should be used.
So an unfused spur using 2.5mm conductors feeding two or more accessories is not permitted, whereas it may be permitted if the conductors are 4mm.
Where an FCU is used, then the conductors can be less than 20A, as long as they have a minimum CSA of 1.5mm and have a CCC greater than the fuse in the FCU.

 

[Pete999]

OP it depends on the design of the circuit, load & method of installation. The use of an FCU on a RFC to supply further sockets etc (appendix 15), relies on the fact that the maximum fuse (manufactured) for load side of the FCU is 13amp. Table 4D5 (insulated & sheathed flat cable) has various ccc for 1.5mm dependant on method on installation.

6242y 1.5mm could be fed via a 16mcb at CU, dependant on type of load, method of installation and consideration of volt drop. Personally, in these circumstances I would consider 2.5mm as a minimum, as demonstrated in Appendix 15.

What he said ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 

[tony mc]

Thanks for all you replys.

Thanks for taking the time to repond just jogged the grey matter which needed a good kick!

Regards
Tony

 

[westward10]

Rarely seen 1.5 MICC on ring finals anymore, and I could be wrong saying this but I am certain it is correct, it does not apply if four core cables are used, whether 4L1 or 4H1. This was a common method once upon a time and is a good spot on an EICR.