Not a BS 7671 requirement as far as I know for plugs/sockets - that sort of thing will generally be left to the specific equipment standards (BS 1363 etc.)

There is a similar sort of thing for switching of protective conductors in BS 7671 (543.3.3.101) - PE can't be opened first or closed last - but that's not really directly applicable to equipment that's covered by other standards.

You don't necessarily have to have a longer pin to ensure 1st make/last break though - the same effect could be achieved with equal length pins by recessing the L&N contacts a little deeper into the socket than the PE contact  - an approach I think the Italian national standard uses for their 3-pin (not Schuko) plugs/sockets.

   - Andy.

And just to be sure, would you agree that the use of 60309 connectors is not a requirement for indoor installations, but is for outdoor installations?

It all depends. There are a lot of factors to consider - IP rating is one (but you can get some BS 1363 outdoor sockets with better IP ratings than many 60309 ones) - physical robustness is another (lighter weight connectors may well not last long in rough commercial or industrial settings) but the biggest is probably current rating - for 32A, 63A etc there's little other choice. There's also a (slightly odd) requirement that high earth leakage devices (>10mA) may be connected using BS EN 60309 plugs/sockets where the same would be prohibited using other types of plugs/sockets (see 543.7).

    - Andy.

Without knowing the type of equipment, ir's difficult to properly advise, because other standards may well apply. For example, if the equipment is part of Machinery as defined in the Supply of Machinery (Safety) Regulations then BS 7671 does not apply at all to these interconnections, but BS EN IEC 60204-1 does.

If it is within the scope of BS 7671, then BS 7671 requires electrical equipment to comply with the latest British or Harmonized standard ... or the installer has to ensure "at least as safe" as, at a minimum, relevant provisions in BS 7671 (See Section 511) ... in the case of plugs, socket-outlets, and couplers (e.g. to BS EN IEC 60320), that are referenced in the general requirements (Parts 1 to 6) of BS 7671, most , if not all, have a longer protective conductor pin, and therefore it could be argued that you'd have a bit of a job covering 'at least as safe' without looking at the complete risk assessment of withdrawing or uncoupling the particular connectors you are looking at. However, if you have to operate an isolator before you have access to remove the plug, for example, that might be considered equivalent safety.

If you are using say 38999 series III for mains (or higher ;-) ), as is actually quite common on NATO military kit, please realise that  these connectors are not designed to be used for making and breaking on load ( - actually a similar caveat applies to IEC 'kettle leads' but the earth pin is early make..)  for equipment solidly connected because it is part of an mechanical assembly like a vehicle fitment, you are not relying on the cable for the sole earth connection anyway. The connector keying is normally chosen so that the use of a particular connector is unique, as there is no generic agreement about pin out. What standard are you building to ? If commercial you may be better with something like the Binders that are aimed at mains.

Mke.

thank you for your replies.

This is industrial equipment located in a mobile vehicle (supply source is external and connected via 400V 63A 5pin 60309 inlets). Within the vehicle are a number of 19” racking ‘assemblies’ which contain the control and power switchgear to heat various pipelines located outside the vehicle via other socket outlets which are also relevant to this thread but my question is specifically in relation to the 19” rack control gear assemblies located inside the vehicle which require interconnecting via plug/socket combinations. The customer is testing engine emissions. 

so to answer your question, I’m not sure if there is a specific standard for this ‘test rig’. I would have thought the majority of it falls under BS7671 (and particularly section 717 ‘mobile vehicles). For control gear assemblies 61439 standard is relevant but this doesn’t state anything on the earth pin length. Most of the equipment I deal with falls under machinery 60204-1  and there are some control valves and pumps on this rig but I wouldn’t class it as machinery. I looked at 60519 ‘electroheating’ which BS7671 mentions but having a brief look through it it generally just redirects you to 60204-1 of other harmonised standards - there’s no quality guidance in my opinion, just redirects! I don’t know it well though so again I probably need to look harder. 

I have another question on these interconnecting cables… it is a multi core cable containing the power circuits to 17 heating elements (230V, most onerous is 13Amps). I want to check if all 17 circuits need their own protective earth core or whether I am ok to use 1 core as a common cpc for all 17 circuits? Put another way could I use 1 x 35 core 1.5mm2 with  34 cores being live neutral for 17 elements and just 1 x 1.5mm2 for the common cpc.

thanks 

Yes, a common c.p.c. is permitted by BS 7671 in general (if that is the applicable standard) - it just needs to be sized to suit the most onerous fault condition - see reg 543.1.2. Keep in mind earth leakage currents (sorry, protective conductor currents) though - as if they might get above 10mA then duplicating c.p.c.s might be back on the agenda (and some kinds of heating elements - esp mineral insulated ones - are well known to be leaky, let alone IT equipment).

  - Andy.

Udtwmc said:

there are some control valves and pumps on this rig but I wouldn’t class it as machinery.

Interestingly, commercial laundry and dishwashing equipment is classed as Machinery, and so is HVAC. A dishwasher really mainly only contains heaters and pumps (the moving spray arms are driven by water pressure and can be stopped by hand without injury usually.

However, if this is a test rig for engine emissions, perhaps BS EN 61010-1 is the most appropriate standard to use (although it wouldn't preclude the use of that with BS EN 60204-1? It doesn't matter how big the 'machinery' or 'test equipment' is, provided you've adopted the standard).

IN any case, I don't think you'd find much different to BS 7671 in terms of plugs and socket-outlets, or connectors/couplers, except that there are not the provisions of Regulation 511 in those other standards (hence no messing around with extra paperwork statements if you want to use SY, CY and YY cables, for example), only the requirements of the relevant legislation to consider (i.e. keep on file manufacturer's specifications and DofCs as appropriate).