This is bad practice, right? |
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rosssss224
Registered User Joined: 25 July 2012 Status: Offline Points: 447 |
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Posted: 14 August 2017 at 4:20pm |
A genny has 32A sockets. Then...
32A ceeform to 13amp plug 'adapter'. Plug amps into 13amp sockets. Amps require a lot less than 13A to operate however in theory 32A amps could be drawn through equipment only rated to 13A. So this is not safe? Am I correct? How bad practice is this (if it is)
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rosssss224
Registered User Joined: 25 July 2012 Status: Offline Points: 447 |
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Or are you protected by the fuses in the 13A sockets?
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kedwardsleisure
Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4938 |
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depends what the wiring's like from the 32a outlet to the 13A sockets. Needs to be 4mm ideally. Most 13A wall sockets in fixed installations are protected by a 30 or 32A breaker or fuse either via radial or ring. Before the regulations went to hell in a hand bag you could only supply 6 single or 3 double sockets from 32A but now the sky's the limit
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Kevin
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rosssss224
Registered User Joined: 25 July 2012 Status: Offline Points: 447 |
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Yeah that is very true - not much different to plugging into a standard supply in a house
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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Standard Uk practice is a "2.5mm T&E ring", so effectively a 5mm L/N CSA conductor to each Socket outlet, all fused off a 32A MCB, with some form of 30mA RCD protection as well. Either 32A RCBO or seperate MCB with semi global RCD. I will ignore the reduced diameter of the earth....
BS7909 would lean you towards 6mm H07, rather than 4mm, but on a short length, if manufacturers spec says it can handle 32A, then you may be able to squeeze 4mm and pass regs. Either way, would have to be H07 because it has to be 450/750V insulation rating. Don't forget the joy (or fudge if you prefer) is that UK BS1363 plugs will have fuses in them. So when you jump from 6mm copper in supply, to 1.5mm in lead to amp, you have a fuse that protects the downstream thinner copper leadset. That is fundamental to the idea of a "32A ring", supplying consumer equipment. Consider the state of it over in Mainland Europe, typically a 16A Shuko (unfused plug), fed off a radial 16A MCB, in 2.5mm CSA (some will use 1.5mm CSA!). When you hop from wall to appliance in 0.75mm CSA flex, it is still fused at 16A MCB. Not pretty. Consider your bedside table lamp in your Euro hotel; in your sleep you knock over your glass of water, and create a smouldering fault, well below 16A to trip the MCB, but your 0.75 h05 PVC smoulders its HSHH (i.e. not LSOH) plastic right up your nostrils. In the UK, the RCD would trip very quickly, and the plug top fuse (for under 1KW - 5A) would also trip before the MCB, and, critically, before the cable melts, and the smoke kills you.
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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Also assumes the GenSet has 32A MCB as a minimum, and, by definition of a Generator being outdoors, you will need RCD, especially as it is a final circuit, so all ways round 32A MCB + RCD or 32A RCBO.
If the genset is really something smaller, it may have a 20A MCB, so 4mm is OK. However, when you next hire a bigger generator with a real 32A, the 4mm might not cut it, so just use 6mm in any 32A connector for future safety and compatibility. Equally for installations 2.5 T&E is a minimum, any sort of derating factors (ambient temp, run in/on insulation, bundling, etc) may uprate that to 4mm or 6mm or bigger, and still fuse it at 32A.
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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I do this:
6mm Ho7 from genset to distro. Distro is one of these: Rubber Box 1409 Then 16A Cee, 2.5mm H07 to 4 way BS1363 socket blocks. For 13A BS1363 to amplifiers, whatever comes with appliance. If it is h05 (pvc) then fine, as long as you note it on your BS7909 sign off sheet.... If you can't afford to buy one, then hire one, around £20-30 a week. 32A RCD incomer, with 4x16A MCB outs. I would prefer a 32A MCB incomer, with 16A RCBO per out, but more expensive, but better discrimination (i.e. only the circuit with the RCD failing fault pops, rather than my one, which, in the event of a RCD tripping event the entire box goes off)
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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