OP
Engineer54
Re: 95 mm 4 core cable, 30 m run, in ducting under buildings backed up by 200 amp fus
I've side stepped nothing!! You have still not grasped the fact were talking about a single circuit, no grouping factors apply whether touching or not touching, ...end of!! Any initial derating as such, would have already been applied by the installation method, not by any grouping factor!! Now is that clear enough for you??
Only a bloody fool would design and run any circuit, parallel or otherwise at it's absolute maximum, your now making up scenarios to suite a non-existent argument!!
Tony's right, this is getting really boring now!!
I think we're all talking at cross purposes.
You've just neatly explained why 2 cables with the same combined CSA as a single larger cable are capable of carrying greater current without overheating compared with the single larger cable, which AFAIK nobody is arguing against.
The question as I see it is whether those 2 cables run in parallel would be capable of taking greater current without overheating if they were run spaced apart or touching.
Engineer sidestepped that question before, but essentially unless you're arguing that there would be no difference, then by definition you're agreeing that a derating factor should be applied when the cables are touching vs when they aren't regardless of whether they are a parallel circuit or not.
I get that if you're not planning the cables to carry anything like their absolute maximum current ratings, as Engineer states he wouldn't, then in reality this isn't going to make a noticeable difference, but that doesn't mean that it's right to state that no derating should be applied for touching cables when you're looking at the absolute maximum loading the cables can take.
I've side stepped nothing!! You have still not grasped the fact were talking about a single circuit, no grouping factors apply whether touching or not touching, ...end of!! Any initial derating as such, would have already been applied by the installation method, not by any grouping factor!! Now is that clear enough for you??
Only a bloody fool would design and run any circuit, parallel or otherwise at it's absolute maximum, your now making up scenarios to suite a non-existent argument!!
Tony's right, this is getting really boring now!!