DIN/IEC - Cable Sizing

[NickParker]

Hello,

The cable datasheet mentions it is manufactured according to DIN standard. It also mentions IEC standard in the same datasheet. Can I use IEC derating factors for these cables as my company only have IEC standards.

 

[krisys]

To be precise, you should get the cable de-rating table from the cable manufacturer/supplier. The IEC table is more broad based.

 

[7anoter4]

According to ABB Switchgear Manual-11th revised edition/2006 VOL.13 chapter 13.2 Cables and wires PVC cable DIN-VDE 0271 it is now DIN-VDE 0276-603/627 and XLPE 0272 it is now 0276-603 also.
The rated current is shown in above standard. However the conversion factor for number of systems[f2] and ground thermal specific resistance, soil temperature and load factor[f1] is in VDE 0276-1000.
IEC 60502-1 does not recommend any current carrying capacity of low voltage cables but IEC 60364-5-52 does.
Let’s take an example of 3*240 mm^2 copper cable XLPE insulated PVC sheathed.
Conditions:90oC conductor temperature, load factor 1[100%] soil resistance 1 K.m/W soil temperature 20oC,number of cable, directly buried[ no conduits].
IEC 60364-5-52 does not make any difference between cable directly buried in soil or in conduit [So does BS 7671].VDE consider 85% for conduits.
The result:
DIN-VDE 428 A
IEC 414 A
It is interesting BS7671 following the same way as IEC the current carrying capacity it is only 382A.
NEC 2014 440 A-but for 0.9 K.m/W[90 oC.cm/W].

 

[NickParker]

Hi 7anoter,

Thanks!

[/IEC 60364-5-52 does not make any difference between cable directly buried in soil or in conduit quote]

Tables B.52.18 and B.52.19 mentions the derating factor for cables buried directly in ground and cables laid in ducts/conduits respectively.

 

[7anoter4]

You are right. The table Table A.52-19 (52-E3) – Reduction factors for more than one circuit, cables laid in ducts in the ground- it presents reduction factors. However, the current-carrying capacities in amperes for methods of installation D [Table A.52-2 (52-C1) to A.52-5 (52-C4)] are for both[directly buried and laid in ducts].
See Table 52-3 (52H) – Examples of methods of installation providing instructions for obtaining current-carrying capacity item no. 70 up to 73.

 

[NickParker]

Hi 7anoter,

I got you. Thank you!