I was more than half-expecting such a comment
It would seem that many people are not aware of this potential exemption from the requirement for overload protection and/or choose not to invoke it. However, even for those who are 'aware', it comes down to an individual judgement as to what loads are "unlikely" to result in an overload current.
As you are aware, even in relation to purely resistive loads (usually heating elements) some people will argue that, in some circumstances (which I would probably regard as 'unlikely'!) an overload current could result. It is certainly less easy to argue that an overload current in unlikley when any motors (often fans) are involved, which applies to many things - e.g. fans i n general, hair driers, power tools and many cooking appliances.
It will be interesting to hear what the situation is in Australia, and whether theree is a corresponding exemption from the need for overload protection when the load is considered "unlikely" to result in an overload current.
Kind Regards, John
I seem to have stirred up quite a "discussion".
Re: -
"It will be interesting to hear what the situation is in Australia, and whether theree is a corresponding exemption from the need for overload protection when the load is considered "unlikely" to result in an overload current."
I cannot find a definitive answer in AS/NZS 3000, which is a "hard to read" document, available only in "paper" format, at the cost of about AUD$250 per edition - and is "copyright".
While I have only "scanned" the later comments, I must point out that any CU Circuit Breaker or Fuse is there
solely to protect the "cabling/wiring" of the building concerned - and to prevent any fault causing overheating and (possibly) fire from such overloaded "wiring".
It is not there to protect any "equipment", nor any flexible "cords" therewith associated.
If a "piece of equipment"
fails in such a way as to draw "excessive current", that "piece of equipment" has already
failed.
It may have internal "overload protection" to limit the current drawn from the circuit concerned but, if not, the current may increase until it is limited only by the resistance of the conductors concerned, until the CU "protection device" operates - or
the internal (short circuit) fault becomes an "open-circuit", due to the absence of sufficient conductive (carbonised) material.
This is the "norm" in Europe (16 A), North America (15 A or 20 A) and Australia (20 A).
In the UK, a "ring" circuit could provide 32 A. However, the fuse in the UK Plug, limits the "overcurrent" (beyond that point) to 13 A - or to some lesser value.
Flexible "cords" operate in "free air" and are (or should be) visible.
With a "catastrophic overload" (short circuit), they would be required to carry the "overload" current for only a brief time, until the "overcurrent circuit protection" operated.
The worst case would be if a "device" developed a fault where the "overload current" gradually increased until it became a short-circuit.
During the period of "gradual increase" the "cord" may be overloaded and become "appreciably warm".
Fortunately, standards are such that a "cord"
rated at (say) 7 A (on a circuit protected by a 20 A circuit breaker) will
not "spontaneously combust"
if subjected to a 3-times "long duration" overload.
However, the insulation may become "soft", due to the additional heat produced in the conductors.
) the answer I gave - that, although you and I had been discussion 'overloads', bernard introduced a situation of a 'fault', and that fault protection is still required even when one can argue that overload protection could be omitted.