Mixed Voltages in Industrial Junction Box.

I think your first sentence is good enough to condemn it.
If some customer or your boss wants chapter and verse, make sure you research it on their time!
Del

The only standard that governs mixed voltages in the same raceway. Is that the insulation on the wires must be rated for the highest voltage. So if one of the lower voltage conductors has insulation not rated for 460vac. Then there is reason for you to condemn it.

Is it 460 V ac or Basic Impulse Level (BIL) ? As far as I know BIL for 460 V system is 600 V as per standard in US.

Junction box or control panel/distribution board?

Photo?

Its an old junction box just over 800mm x 800mm made of mild steel plate and is absolutely packed. The machine it is fixed to is being refurbished and the owner is keen to rebuild the JB as it is. My own thoughts are that its madness and will be featured in an accident report. There is a gap between what we both believe to be a safe installation.

Sadly all of the cables are rated sufficient for the voltages contained within the panel. My recommendation is to condemn it. I just can't believe there is no standard to cover it - even things like shrouding and labelling.

Sounds like a control panel.

If the wiring is in a dilapidated state then you can condemn the wiring and have it rewired. If on top of the dilapidation the enclosure is so jam packed with (most likely) add-ons that it was never intended to accommodate then you may have a case for installing an additional outboard junction box to allow structured wiring practices to be reinstated.

If it is really jam packed it may well be thermally overloaded as well which gives you another avenue for a replacement or augmentation justification.

Do you have the original drawings?

Its absolutely a junction box. There are 7 vertical rails of Klippon type teminals of varying types. It has a lid on and needs tools to get into it.

The safety culture we follow today the younger guys know if it hasn't got a shroud on it chances are its safe. Similarly they also know that you don't mix up voltages and a random 460V 2 phases next to 110VDC with a battery on the end of it.

It meets all of the cable voltages and creepage.

The older ones know to expect rubbish so are pleasantly surprised when we see a new modern panel.

Still no standards though?

Here's one reference.

This one around page 30

A penny pinching owner, more concerned with saving a few $ rather than safety and ease of servicing?

Who'd have thought it?

If you really want to do it, show him the cost of adding a second box to allow it to be tided up a bit and point out the maintenance savings of having it clearly labelled and spread out.

Point out it will probably take less time to improve the layout.
If he still wants to just rebuild it... let him get on with it!

Del

We're getting into the realm of acceptable installation practices and risk mitigation...

Too many beers now to continue blithering.

To be continued....

If this was an issue in a Canadian jurisdiction, the content of rule 12-3030 would be used to fail this installation... perhaps the BS that Mr. Slack always mentions has a similar requirement.

12-3030 Conductors in boxes, cabinets, or fittings

(1) Conductors that are connected to different power or distribution transformers or other different sources of voltage shall not be installed in the same box, cabinet, or fitting unless

(a) a barrier of sheet steel not less than 1.3 mm thick or a flame-retardant non-metallic insulating material not less than 1.6 mm in thickness is used to divide the space into separate compartments for the conductors of each system;

(b) the conductors are used for the supply and/or control of remote devices and are insulated for at least the same voltage as that of the circuit having the highest voltage and none of the conductors of the circuits of lower voltages is directly connected to a lighting branch circuit; or

(c) the conductors are used for the supply of a double-throw switch in an emergency lighting system.

(2) Where a barrier is used, it shall be fastened rigidly to the box, cabinet, or fitting, or a device assuring positive separation of the conductors shall be used.

Like the Canadian code Mr Slacks publication contains a similar section regarding segregation of voltages. Unfortunately the UK regs also have part 1 110.2 which specifically excludes various installations - part v being mobile and fixed offshore installations.

Hopefully this issue will get no further than a winge here and will not result in a health and safety enquiry.

If the junction box is used for intrinsically safe wiring used for hazardous areas, then ANSI/ISA-RP12.06.01-2003, Recommended Practice for Wiring Methods for Hazardous (Classified) Areas, Part 1: Intrinsic Safety, requires separation distances and separation barriers.

504.30 Separation of Intrinsically Safe Conductors.

(A) From Non intrinsically Safe Circuit Conductors.

(1) Open wiring. Conductors and cables of intrinsically safe circuits not in raceways or cable trays shall be separated at least 50 mm (2 in.) and secured from conductors and cables of any non intrinsically safe circuits.

(2) In raceways, cable trays, and cables. Conductors of intrinsically safe circuits shall not be placed in any raceway, cable tray, or cable with conductors of any non intrinsically safe circuit.

Exception No. 1: Where conductors of intrinsically safe circuits are separated fromconductors of nonintrinsically safe circuits by a distance of at least 50 mm (2 in.) and secured, or by a grounded metal partition or an approved insulating partition.

(3) Within enclosures.

(a) Conductors of intrinsically safe circuits shall be separated at least 50 mm (2 in.) from conductors of any nonintrinsically safe circuits or as specified in 504.30(A)(2).

I'm sure the standards over the pond reflect similar restrictions, but I don't have those documents.

If you adhere to the local code, you should not regenerate the same condition you found. Any electrical update to the machine should be upgraded to the most recent code. I would not perform any upgrade without doing so!