Joined: 25 July 2008
A layout drawing for a large heating appliance was sent to me recently for comment, as I'll be defining the wiring layout soon.
The controls include a user dual channel timer, user display, boiler control PCB, system control PLC, relays, fuses.
The wiring scheme includes 230V LV controls, 24V SELV controls, thermocouple and thermistor wiring.
My design colleagues have decreed that ALL the controls will be mounted on the front, hinged door of the appliance (opened with a tool), while all their pipes, pumps, valves et all reside permanently fixed in the appliances main chassis.
This results in approximately 54 conductors of all the wiring types mentioned above, having to be flexible aroud the hinge. A huge, heavy unsightly and difficult to build unmbilical. There is no scope for any 'nice' large diameter flexible conduit or such thing, there's no room for bulkhead fitting, etc.
Personally, I can't accept this as good design and have protested so. My decree is that only the user timer and user control should be on the door because they are designed to be.
I have to make a formal defence in a meeting this Weds 27/6.
Our core standard to meet is BS-EN 60335 (2012) which would allow such a design with loads of sleeving, earth wiring and other mitigation.
Any good arguments that support my 'bad practise' suit would be greatly appreciated!
Thanks in advance.
Joined: 16 July 2011
hmmmm 54 conductors of 1mm2 tri rated cable isn't a big bunch and as this will be fed i guess from a 13A fused spur none of the cables really need to be bigger than 0.75 or maybe even 0.5.
Bad Pratcise doen't mean it wont comply, sounds like you may be on a loser, it depends how much you value your job
Joined: 04 April 2006
You could have a bit of a compromise here, I have seen machine builds with controls on the sides of the enclosure to minimise door wiring.
However you mention valves and pumps, whats going to be the damage if a leak sprays over the 240V side of things.
Where there have been fluids, I have normally seen those in a separate enclosure adjacent enclosure, apart from pneumatics.
Have you also considered an enclosure within an enclosure to protect from jets of fluid.