I suppose that depends upon what you mean by "adequate protection from the elements". Protection from water ought to be achievable, but what about temperature?It's certainly not an issue provided you can allow adequate protection from the elements. You'll find normal MCBs, RCBOs etc in external cabinets for streetlighting feeder pillars for example.
What about the 'top end' of the temp ratings? Even in the UK, air temperature can get up to 30°C, or a bit higher, so I find it hard to believe that the inside of a cabinet exposed to direct sunlight could never get above 40°C.You're best getting a little heater (say a Pentagon 20W) plus thermostat set to 5°C. Anything lower carries a risk of condensation and corrosion.
Fair enough - so, as I asked aptsys, does that mean that you feel it would be acceptable to 'ignore' the manufacturer's stated maximum operating ambient temperature (on the grounds that you didn't think it would be exceeded by much and/or for very long)? (all MK devices that one is likely to find in a CU appear to have max ambient temp ratings of 40°C).The "outside" industries such as the railways and communications don't worry too much about the upper limit as it's not usually that hot, and certainly not for long.
Yep, this is the normal wayYou're best getting a little heater (say a Pentagon 20W) plus thermostat set to 5°C. Anything lower carries a risk of condensation and corrosion.
Fair enough. However, I can't really see how the ambient temperature inside a UK house could ever be anything like 40° - the operating temp within a CU (and components therein) of the is obviously a different matter. As for outdoors, objects left in 'full midday sun' (like my metal garden furniture!) can get far too hot to touch, so a lot above 40°, but I don't know what the temp inside a cabinet might reach.Probably more likely to exceed 40deg indoors, it's not likely at all. Presumably it can be 40deg ambient temperature outside the cabinet and a fully loaded board with all breakers carrying their full load (with the heat that generates), and that is never going to happen in a normal domestic setting.
agree re comms industry, virgin media weren't too worried about the odd scorcher, in one place our internet used to go off for a few hours on any hot and sunny day. Eventually when an engineer came they said it's if the cabinet is in a warm position with direct sun, it just overheats and shuts down for a while. But it's too expensive to relocate.The "outside" industries such as the railways and communications don't worry too much about the upper limit as it's not usually that hot, and certainly not for long. It may approach the limits but the likes of cabinet manufacturers and assemblers don't seem overly concerned by the threat of an odd scorcher.
That's very possible, but we just don't know the reason. As I've said, it really wouldn't concern me very much, but in comparable situations, people have thrown at me "specs are specs" (and/or "regs are regs", in the days when BS7671 required compliance with MIs)!The MCB limits might be more about tripping too early in hot temperatures. If they don't comply with the curve then that temperature won't be allowed in the spec.
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