Acceptable wiring methods for machine tool

[CanaDon]

Is is acceptable to run YY cable through box sections (square or rectangular tubing) that form the structure of a machine tool? This is for power and control, all 48VDC or less.

Would it be good practice to route the cables through flexible non metallic conduit where it penetrates or passes through a box section or structure?

If anyone can direct me to any applicable core requirements or sections of the machinery directive that apply to this I would appreciate it.

Thanks in advance.

 

[Darkwood]

Hard to give advice without pic of machine or spec on it, every circumstance may be different and warrant a different approach but if you are not weakening, obstructing (for maintenance), running cable in environment where its exposed to been damaged or trapped etc etc then cant see a problem but deffo more info too even give a credible answer.

 

[silva.foxx]

Personally I prefer to use a cable management method, such as using the fit-for-purpose flexicon or tray, as opposed to lashing-in a cable. I've seen lashing-in quite often, where contractors run cables along pipes and framework or threading through conveyors! Then...when a change is required...these cables have to be taken back, cut and jointed or some other remedial work.

 

[CanaDon]

I cannot post a photo of the machine but I can give you a little better description.

Machine is 15m long and 3m wide, PLC/Power distribution at one end. THere are about 40 cables from the PLC that need to be routed inside the machine but cable routing is limited. One obvious route is a 100x200mm box section that runs from the PLC to an area in which I can run a cable tray.

I prefer to run flexicon from the PLC through a 2m long box section to the cabletray but I have been told that this is just a waste of money, I believe it is good trade practice.

Some of the cables running through the flexicon are 100amp dc, together with ProfiNet, canopen, Ethernet and 24VDC control.

Any thoughts?

 

[Darkwood]

Even with your extra info its still a hard call to make as a pic would say a thousand words where as we would be going around in circles asking questions and getting nowhere fast, but given our advice you may be able to put a good argument for a cable tray or trunking by assessing maintenance and possible repairs the machine would need if something went wrong and as silva pointed out say alterations or part of the machine requires to be sent off site last thing you want is to be unwiring everything.

 

[mheyes]

I just want to start my reply by saying this is a very grey area. I agree the ONLY option you have is to put a cable management system in. Be aware that you must keep you AC power well away from your comm's. I would also wire your safety circuits in SWA it makes it very hard to bypass.

It’s not just the machinery directive you also have en62061,en ISO 13849-1

Remember it’s your backside if something goes wrong and as I always say to my boss “it might cost money now but will save money later”

 

[netblindpaul]

^SWA as recognised by most under BS7671, is not suitable for use on machinery.

 

[mheyes]

The only reason we use SWA on safety circuit’s is that a maintenance engineer decided to re route a cable passed a rotating shear blade. The original cable was a 19 core SY that the blade took great pleasure in chopping through. This single event sparked an investigation that lasted month’s as we have put 9 of these machines into the clients site. We had to replace all the safety circuits that where wired in SY with SWA and where slapped with a massive bill for lost production.

Since then we now install an ASI safety system so if maintenance engineers want to do mod’s they can splice into the main line without disturbing any of the original wiring.

 

[silva.foxx]

The only reason we use SWA on safety circuit’s is that a maintenance engineer decided to re route a cable passed a rotating shear blade. The original cable was a 19 core SY that the blade took great pleasure in chopping through. This single event sparked an investigation... replace all the safety circuits that where wired in {flexible} SY with {rigid} SWA...

I assume it wasn't the client's Maintenance Engineer.
Surely, any decent spark would route it through some form of additional protection; metallic conduit springs to mind! In positions of high mechanical damge risk extra protection is a must.


Going back to the OP question... I have seen numerous machines, typically MeadWestvaco basket packers, what have utilised box section as a cable carrier. These have signs attached stating 'Do not drill. Cables enclosed'.

I've witnessed a guy drill a machine frame and damage the cable enclosed, this was on a bottle filler. No hint that it was used as a CMS. Very fortunate that the motor wasn't running else that cable would have been live!

qwertyuiop

 

[Wazzajnr]

I used to work for a machine builders up until about 18 months ago and the box sections are always used for routing cables.
3 things to note,

1)the machines were designed with rectangular cut-outs at regular intervals on the machine to facilitate wiring/maintenance
2)entry into the box section was made by drilling and tapping 32mm (or 50mm if box was big enoough) and then a short reach bush screwed in with threadlock
3)a seperate box was used for power and comms/analogue cable run to avoid interference.

The company has been making machines for 30+ years and to my knowledge, nothing has ever come back because of running in the box sections. at the end of the day, it is hardly any different to running in trunking or steel conduit

Hope this helps

 

[silva.foxx]

I used to work for a machine builders ... and the box sections are always used for routing cables.

The company has been making machines for 30+ years and to my knowledge, nothing has ever come back because of running in the box sections. at the end of the day, it is hardly any different to running in trunking or steel conduit.

There you are...the textbook answer. Cos it's been done for thirty years with no issues then it's a time tested proven method.

 

[Wazzajnr]

Silva,

That wasn't what i was trying to say to be fair. I was merely pointing out that it is an accepted practice in machine building and personally, i see no reason why it shouldn't be providing the cables are protected why should it make any difference if it's by conduit, trunking or the fabric of the machine??
Is it so different than burrying cables in the fabric of a building???

 

[silva.foxx]

I'm agreeing with you, in principal... as long as its clear that cables are enclosed, accessible and secure (and safe from chafing and sharp edges)... but what occurs when the cables need to pass from the box section, were they still protected?

What I've seen last week was singles (76 cores in one case) passing from one trunking to another via a length of liquidtite flexi-con inserted 3" into the end of each trunking. Do you think this is acceptable?

 

[Wazzajnr]

Sorry Silva, i thought you were being sarcastic.
We never EVER used singles through the box section, only CY/SY/belden etc and in most cases, it would exit the box section and straight into the kit it was feeding or straight into the plinth underneath the panel.

These perhaps aren't the best 2 examples of what i mean but maybe give you an idea

 

[silva.foxx]

Sorry Silva, i thought you were being sarcastic.

Sar-car-stick... me? Not in my nature...unless you know me.
Thanks for the photies!

 

[Wazzajnr]

You never know with some of these forums, I've just been lambasted for dragging up an old post oooppppssss!!!

 

[Engineer54]

I used to work for a machine builders up until about 18 months ago and the box sections are always used for routing cables.
3 things to note,

1)the machines were designed with rectangular cut-outs at regular intervals on the machine to facilitate wiring/maintenance
2)entry into the box section was made by drilling and tapping 32mm (or 50mm if box was big enoough) and then a short reach bush screwed in with threadlock
3)a seperate box was used for power and comms/analogue cable run to avoid interference.

The company has been making machines for 30+ years and to my knowledge, nothing has ever come back because of running in the box sections. at the end of the day, it is hardly any different to running in trunking or steel conduit

Hope this helps

Virtually every machine build i've seen of any size, has been built to use the fabric of the machine for it's wiring and air piping systems etc. A good many also use them for flush mounted switches and push button locations... Basic standard practice i would have thought. Only ever seen singles run in box sections etc in very old machines, and i guess many of them are still around today giving sterling service. They don't make em like they used too, those old machines were built to last and last they did!! lol!!! Think they call it ''Over Engineering'' today...lol!!!

 

[gnuuser]

actually i recommend trunking the cables in raceway or conduit.
(had to completely rewire a carton erector after someone welded safety rails on a frame section carrying cabling)
lots more smoke than they expected and stink quite a bit.:lol:
they were un-aware that cabling was run in the framework

 

[Engineer54]

actually i recommend trunking the cables in raceway or conduit.
(had to completely rewire a carton erector after someone welded safety rails on a frame section carrying cabling)
lots more smoke than they expected and stink quite a bit.:lol:
they were un-aware that cabling was run in the framework

That's fine if there is enough space/room on the machine to incorporate a conduit or trunking system. Most manufactures will use the framework to route cabling, air, hydraulics etc, around the machine. Generally you wouldn't use the fabric of the machine to house the incoming supply cable, though i've seen that done a few times too....