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HO7RNF Cable vs US equivalent

H077RNF is used a lot a lot in the entertainment industry. The North Americans use a similar cable (Page 5) but it has a paper separator between the cores. Often seen the US cable come to the UK on tours but was curious to see if it satisfies BS7671?  

  • the biggest problems are likely to be

    1) The non-standard colours of the cores - here brown is live and blue is neutral, and earth is indicated by green and yellow stripes. White black and green are not quite the same. However, oversleevng at the ends may be enough to comply,

    2) the non standard way of expressing voltage ratings - we'd expect to see two figures, a core to ground rating and a core to higher core to core figure - e.g.300/500 or 600/1000.

    So some work would be needed to verify equivalent level of safety, though I suspect that in practice of course a serous problem is very unlikely, and arguably as  the appliance flex is not normally considered part of the fixed installation, BS7671 is not that relavant, far more serious is the change of voltage and the various phase arrangements that larger US machines expect.


  • As Mike says - likely bigger fish to fry and for temporary setups for tours then BS7909 may be more applicable to check against.

    I guess you're not suggesting using it in a fixed installation.  It's made to a US standard so you may get away with it under section 133.1 with some careful thinking and paperwork (and oversleeving...).  Not advised though and I have had some spectacular arguments on construction sites about cable selection in the past!

  • The cable would never be used in a fixed installation and would in fact have plugs and sockets already wired on the end of the cable. I get the point on the non standard colours but they hopefully would never be taking the plugs and sockets off, however the fact is they could if they wanted. It is BS7909 but there isn't anything about the paper in the cable in that or BS7671. Thanks for you help 

  • I have seen paper separators in cables in the UK and plastic sisal type string in SWA cable, it’s just packing material to help shape the cable and and to stop things sticking together, it doesn’t have insulating properties and is of no significance.

  • I doubt there could be any objection to the paper per se - a significant proportion of UK installations are fed by cables that use paper as the basic insulation (PILC - paper insulated lead covered cables) - and in this situation (as others have already said) there's no reliance on its insulating properties, so the lack of moistureproof sealing isn't likely to be an issue.  I've worked with IT equipment supplied by very large reputable manufacturers into the UK that's come with US flex on it (that was a bit of a challenge until you worked out the US colour code!)

    Actual specifications for cables did used to exist in the wiring regulations many many moons ago - but they've long since been relocated to specific cable standards. BS 7671 now only concerns itself with the choice of a suitable standard (same for cables as for all other equipment that forms the installation) - as has already been said - 133.1 while preferring a UK, EN or IEC standard, will accept a 'appropriate standard of another country'.

       - Andy.