Third party modifying a Commercial Machine

I see no harm IN PRINCIPLE in a third party modifying large or complex machines, It would be unduly restrictive to state that large or complex machines should remain in “as supplied” condition, rather than being modified to reflect changing needs.

However in this particular case it sounds as though the modifications may be of doubtful quality. I would prefer that the added small motors be controlled via a dedicated relay or contactor that incorporates overload protection. The coil supply for this could reasonably be obtained from the load side of the main contactor to ensure simultaneous operation. Depending on circumstances, fuse protection may be needed as well as the overload trip.

D32 has quite a high let through energy, if there is a dead short, then budget for buying some more SY unless your pssc is low.

It is not dangerous, but I agree its a bit slipshod.

Mike.

I think that the manufacturer should give approval, if only for any or warranty or insurance.

Jaymack 

Why wasn’t OEM equipment ordered from the machine manufacturers to be installed by them or their contractors?

Presumably the SY cable comprises insulated live conductors that are then over-sheathed with additional insulation. The steel braid is then just in place for  mechanical protection.

Z.

I'm afraid I don't understand your problem. The SY braid probably should be Earthed, but as a defect it is very unlikely to be dangerous to anyone.

I think you have the wrong idea that this product modifies the machine, it does not, it adds another product to be used with the machine. Can your CNC turn the mist coolant on and off? This is usual with the normal liquid coolant supply so the mist system should be fed from the same contactor. As an example, I have a digital readout system on my lathe. This “modifies” the lathe in that a few bolts are added to fix the scales etc, but the machine is not operationally different in any way. It also has a VSD fitted, and as a result, it has an additional constant speed oil pump, in place of the main motor driven one. As long as the machine is still compliant with the machinery regulations, and I see no reason why it does not from your description, there is no problem fitting anything you like.

Agree, and taken to the logical extreme, what about a vehicle assembly line ? Is that a single machine ? Minor modifications are made regularly to improve output or reliability or to cater for minor alterations in product.

What about food factories ? Some are very complex and regularly modified as needs change.

In this case, BS 7671 only goes as far as the supply to the Machinery (as defined in the legislation) - see Regulation 110.2 (xii).

The very real issue is that the electrical system of the machine has been altered. A BS 7671 certificate (EICR or MWC) is not appropriate for this work, as it's out of scope.

So, in terms of the Supply of Machinery (Safety) Regulations, what paperwork is available? I'm guessing that the newly installed system components already have Declarations of Conformity (or UK equivalent) … which then leaves the  evidence of Verification according to Clause 18 of BS EN 60204-1. The standard requires that testing (re-verification) is considered when a portion of the machine or associated equipment is changed or modified.

This should be documented one way or another I think.

Who is responsible? I guess it depends on what the installer and supplier were contracted (or asked) to do?
For example, if it was “We need a modification doing can you advise us?" there's a different answer to “Just come and fit one of those for us” (the latter would put most of the design responsibilities , and possibly test responsibilities, on the person requesting the work, I guess).

The question is one of how ‘serious ’ the change is. If for example it involved cutting into the wiring for an E-stop it would require far more thought than this example and that would become one where maker's buy-in would be needed, or a review of the whole safety system to compare the before and after for all sensible cases.

 Here, only an LV supply is being lifted  for some ancillary - this is almost at the level of plugging in a sump pump or an extra operator light, so low risk, but even then there should be a record of how power was tapped in, and some justification that it can in no way can it impair the normal operation. Adding a load that had potential to cause RF interference for example would be a different matter.

There ought to be a clear trail so the person who is in effect accepting the risk, knows they are and is happy with it.

Mike.

mapj1: 
 

The question is one of how ‘serious ’ the change is. If for example it involved cutting into the wiring for an E-stop it would require far more thought than this example and that would become one where maker's buy-in would be needed, or a review of the whole safety system to compare the before and after for all sensible cases.

 Here, only an LV supply is being lifted  for some ancillary - this is almost at the level of plugging in a sump pump or an extra operator light, so low risk, but even then there should be a record of how power was tapped in, and some justification that it can in no way can it impair the normal operation. Adding a load that had potential to cause RF interference for example would be a different matter.

There ought to be a clear trail so the person who is in effect accepting the risk, knows they are and is happy with it.

Mike.

 

Not only the “trail of blame”.

BS EN 60204-1 requires circuit diagrams necessary for repair. These need to be updated.

Are the original ratings of equipment, supplies and enclosures still correct - who's updating that info?

All based on the assumption of course that the connection won't impact any EMC measures or testing of the original manufacturer … who's checking that? And of course this could also relate to the SY cable. If one of the manufacturers recommended SY to be used, SY is used for EMC purposes, NOT mechanical protection … so the braid should be earthed, via a proper 360-degree gland … or YY (or a suitable flexible cable such H07 RN-F) should have been used instead.

Too many open questions in my mind from an assurance point of view.