I have a copy of pages 136 & 137 of the 13th edition regs (defo from 1966, so I think it's 13th ed). These pages have the tabulated ratings for imperial cables (table 3). Above the table in bold print it says: "The ratings tabulated apply where the cable is provided with coarse excess-current protection. For close excess-current protection see rating factor below" In the rating factors below the table it says: "The ratings tabulated may be multiplied by 1.33 where close excess-current protection can be assured (see item 2(b) on page 127)" Does anyone out in Screwfixforumland have a copy of 13th edition and can either reproduce the text of item 2(b) from page 127 in this thread or post a scan on a photo host site? I want to know what is meant by close and coarse excess-current protection. My current interpretation is that course is 3036 rewirable and close is 1361 fuses or MCBs. This would certainly make sense as the 1.33 multiplication factor applied to table 3 would be the same as the 0.75 factor applied to 16th ed'n ratings for 3036 rewirables. My ultimate goal here is to understand imperial cable ratings better as I come across a fair bit of it during CU changes.
If my memory serves me correctly, long time ago the 13th. Course protection I believe referred to rewirable fuses & close protection referred to cartridge fuses, if im wrong someone will soon tell me.
Got a copy of the 14th edition, could email page 127/128 if you let me know your email address, got p...ed off with trying to put it on photobucket