There are a few options.

You can stay with the larger wire size right through to the protective device as even small IEC 60947-2 breakers, down to 0.A for example will normally take at least a 25mm sq conductor.  Quite possibly 35mm sq.

If you are larger than that, have you considered a bus bar system, or the distribution blocks, think Henley blocks but for machine panels, the big panel guys make them, I think Weidmuller do, ad you have mentioned their terminals.  Weidmuller WPD range for example.

Also you mention a PDU6/10 which I'm not 100% familiar with as I am a WDU user, a WDU terminal is suitable for 0.5 to 10mm sq stranded, so you could connect your 10mm one side and your 1.5mm the other off to your downstream protective device to ensure that the 1.5 cannot be overloaded, and as long as your installation methods are sound, then you could negate upstream fault protection as long as the wire run is of an acceptable length.

Weidmuller documentation for the PDU 6/10 specifies a flexible wire size with ferrule, of 1.5 to 10mm sq, which would be your "tri rated" and a "bootlace ferrule" which you should be using for compliance with the LVD or MD as appropriate and EN 60204-1 if you are using the harmonised standards route to claiming your presumption of conformity.

So you could easily step down from 10 to 1.5 in a single terminal, a PDU 16 goes down to 2.5mm sq.  A WDU 50 will go down to 6mm with ferrule a WDU95 goes down to a 16mm sq with ferrule.

So I think that you have a few options there, with the manufacturer you are using.


Just remember almost certainly, if the drive panels are for machinery of some sort, then the requirements of EN 60204-1 will apply not BS 7671, you may also need to refer to some of the requirements of EN 61439-1 for certain aspects of the equipment if you design and manufacture any of your own product and this forms part of the panel.

If you stick with "off the shelf" product, then you can almost certainly steer clear of the requirements of EN 61439-1, just remember that your integration documents must be suitable and sufficient.

EN 60204-1 is harmonised to both the MD & the LVD.

Please note that there are other terminal manufacturers, it just so happened that the OP mentioned Weidmuller, and I am familiar with their products.

In my earlier post I have 0.A, I meant 0.5A!

Oops, sorry.

Thank you Paul for an extremely helpful reply.  It's good to know that I was thinking along the right lines in applying EN 60204. I'm now looking at the WDU terminal and have obtained a copy of EN 61439-1.


John.

Hi John,

Don't forget though, that you also need to do any safety systems in accordance with the ISO 13849 or 62061 series, and e-stops in accordance with ISO 13850 if your going to go down the route of standards.

Also if the panels are for machinery, then it's the MD rather than the LVD you need to be looking at.

There is little in 61439-1 that applies, unless, you are for example designing and building your own copper busbars and supports from first principles & raw materials, only really where 60204-1 calls it up.

Oh and a lot of hoisting equipment is 60204-32 rather than -1.

Plus all the others!!! 

Robert,

Yes that is true of BS 7671, however, machinery controls are excluded by virtue of 110.2, xi.

He machinery electrical standard has something similar, but both, allow a short distance reduction in cross sectional area to be protected against overload at the downstream end of the wiring, as long as the short term fault current is protected against upstream end.

Machinery wiring standards also require that the maximum fault energy at connected devices is controlled & limited by the upstream circuit protection, especially for compliance with the requirements for elimination of common cause failures in safety systems.

Robert,

I will agree with you that calculations are required, but disagree that it is anything to do with BS 7671 with this being a machinery control systems.

110.2, xi excludes machinery control panels which are covered by EN 60204-1, from the scope of BS 7671.

Therefore bring this standard into the discussion is irrelevant.

For anything covered by the Supply of Machinery Safety Regulations, BS 7671 is irrelevant as it is not a harmonised standard.