Discuss VIR Cables Current Carrying Capactiy in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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graham123

Anyone know of any information out their on the current caring capacity of old VIR cables, looks like they are between 16mm-25mm, so any info on the older imperial sizes would be useful

Thanks

graham
 
i'll hazard a guess at 19/.044, which equates to approx. 20mm². to be on safe side treat as 16mm², or interpolate between 16 and 25. assuming state of cables is fit for continued use.
 
The bigger submains appear in good condition from what we can visually see. the small stuff is in a bad way.
19/0.44 cables are on 63a mcbs
 
The bigger submains appear in good condition from what we can visually see. the small stuff is in a bad way.
19/0.44 cables are on 63a mcbs
looks about right to me. 80A is about the max. if in free air .

0.03 19/.044 80A 105A 125A 115A 125A 135A 90A 110A 115A ... VD. 2.4/ 2.1
 
I've got a few old regs books with ratings tables for this cable at home, if I remember when I get home I'll post up some pictures.

Do you know what type and age of cable it is?
 
Anyone know of any information out their on the current caring capacity of old VIR cables, looks like they are between 16mm-25mm, so any info on the older imperial sizes would be useful

Thanks

graham
file:///C:/Users/Pete/Desktop/Petes%20resources/Electrical%202/cable_sizes.pdf
 
I found this extract in my files, may be of some help...?


The 1955 13th edition IEE Regs is the last one in which I can find a reference to rubber insulated cables (ie Vulcanised general purpose Rubber compound Insulation to BS.7, as distinct from butyl rubber).
Table 13 of those Regs gives ratings for flat twin, and 3-4 core cables, installed "in conduit, troughing or casing" as well as in "free air" - including rubber insulated cables with tough-rubber sheathing or lead sheathing, and pvc or polythene insulated cables with pvc sheathing.

conductor size …. single phase current …. ECC if lead sheath+T&E …. ECC size if pvc
1/.044 (0.0015 sq in) …. 5 amps …. no ECC listed for this …. 1/.044 (0.0015 sq in)
3/.029 (0.002 sq in) …. 10 amps …. 1/.036 (0.001 sq in) …. 1/.044 (0.0015 sq in)
3/.036 (0.003 sq in) …. 15 amps …. 1/.044 (0.0015 sq in) …. 1/.044 (0.0015 sq in)
7/.029 (0.0045 sq in) . 20 amps …. 1/.044 (0.0145 sq in) …. 3/.036 (0.003 sq in)
7/.036 (0.007 sq in) …. 28 amps …. 1/.044 (0.0145 sq in) …. 7/029 (0.0045 sq in)
7/.044 (0.01 sq in) …. 36 amps …. 1/.052 (0.002 sq in) …. 7/.036 (0.007 sq in)

then getting up to more industrial sizes
7/.052 (0.0145 sq in) …. 43 amps …. 1/.064 (0.003 sq in) …. 7/.044 (0.01 sq in)
7/.064 (0.0225 sq in) …. 53 amps …. 1/.072 (0.004 sq in) …. 7/.052 (0.0145 sq in)

How many people remember working with lead sheathed twin cables, going into metal junction boxes with a snap-on metal lid and screw down clamps to secure and earth the cable sheaths?

The cable sizes are the actual diameter of the individual strands in each cable - in inches - (so 3/.029 was 3 strands of 0.029 inch diameter cable), so cable sizes could be readily checked with an imperial micrometer.
I guess my mic is not the only one with a burned up anvil where a cable was carelessly checked live and the rest of the mic touched to earth (my shoes or the flooring must have been good insulators in those days! )
 

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