Perforated Cable Trays Vs Rodents

I can't see how cable tray can be rodent proof. Surely you will need to enclose the cables and seal the enclosure properly if you have rodent concerns.

Gary

I guess if you're enclosing the cables so the perforated tray form one side of the enclosure and are worried about mice getting through the holes ... mice can get through extraordinarily small gaps - the usually saying is that a gap the size of the width of a pencil is enough - although I think that's referring to the smaller dimension of a long/thin rectangular gap rather than say a circular one. Still warm dry sheltered places are very attractive to rodents and they can be very persistent, so I might be tempted by something a more solid (trunking say).

   - Andy.

We can say that if the perforation size is 2.5x1cm and the cover is solid, the installation is not safe from rodent attacks, as long as the cables are not armoured?

Trunking systems aren't always impervious to rodents ... mice can get through holes as little as 6 mm in diameter, which would certainly achieve the minimum for surfaces  of IP2X/IPXXB (except, of course the top surface which would have to be IP4X/IPXXD).

I'd certainly expect mice and small to medium rats to be able to get into a 2.5*1cm aperture and set up home on the other side, but not squirrels, large rats, or rabbits.
All of these species have continuously growing teeth that they like to knaw down when they get uncomfortably long, and that is often making holes in random bits of wood or or stripping any soft skin cables. and even on SWA they can expose the armour, and if they nest and then also use the area as a loo, the exposed metal then corrodes surprisingly fast.

regards,

Mike.

(Ps luckily for us kangaroo damage is not a problem in the UK.)

Depending on the situation, there may also be the consideration that if it's nearly rodent proof, you'd have created an armour-plating for a warm, predator-proof nest, when exposed cabling would be less attractive and could be inspected for damage easily (i.e. regularly).

Neither of which is an argument to do nothing, of course. Just that boxing in may not always be the answer.

IP XXD or B are is also certainly not mouse proof - both permit finger or thin screwdriver access, so long as the finger or spike does not touch anything that can come live - so can touch things like cables or other covers that are single insulation.

The hole can be any size or shape that does not admit a 34.8mm diameter ball for IP XXD - so a 34.7mm slot a metre long would do, or for IPXXB  a 50mm disk so perhaps a 49mm wide slot. 

Arguably minitrunking with the lid off and insulated singles exposed to view meets IPXXB or even D ...
and is really a bit poor for the top of anything. The wording of the regs suggests near equivalence  between IP4x and IPXXD, and really there is not. The IP (number) requirements are far tighter. 

Mike

Actually, I agree it's better to choose fully enclosed solid bottom, sides and cover  trunkng, however, the installation is in place where high ambient temperature (55C) is expected and being exposed to direct sunlight, so I was thinking of perforated cable tray so as to keep a room for heat dissipation through natural ventilation although the cables will not carry any significant current. but the control cables are somehow sensitive as there max operating temperature is 70C.

We have seen ladder / 'strut-work with stamped perforated mesh steel used as an all-sides wrap-around, providing ventilation and some choice over hole size to suit your choice of rodent, plus you can still see the condition of what's inside. Sounds like an expensive solution for control cables though.

If you've got direct sunlight, particularly in a warm location with rodents (so trunking, therefore, is likely to not stay as shiny steel for long), could you also have an issue with solar gain?

Is there a reason why the cable can't be armoured?

15K temperature headroom sounds a bit like the wrong cable though.

It's the availability of armoured shielded control cables.

However, I will consider either XLPE insulated shielded control cables inside enclosed trunking or XLPE armoured inside covered perforated cable tray, whichever available. Thank you.