Putting a 4 inch extractor fan with pull cord .... I was wondering is the fuse spur important or a normal 1.5 from the light connection would do the without it effecting any regulations ??
1..If you propose to run off bathroom lighting circuit is the said circuit RCD protected? 2..If you want to use FCU be it orf the Ring Final or Radial Final..is the circuit used RCD protected?
Well if its one of those so called 17th Edn CU's then whatever you do must comply electrically if you know what you are doing. However that aside there are other factors to consider..ie zoning etc etc. Competency is the key word, and there is no circumventing from that default requisite OP. And then there is that Part P and stuff..I dunno really.
I was wondering is the fuse spur important or a normal 1.5 from the light connection would do the without it effecting any regulations ?? A 4" 20W domestic fan will be quite happy running directly from the lighting circuit without the need for a fused spur, and it would also satisfy 'Regulations'. However, it might not satisfy the Manufacturer's Instructions, as they often specify the use of an 3A FCU. The 'Regulations' state that the Manufacturer's advice should be taken into account - this has led to some people believing that the MI's take precedence over the Regs - which of course is nonsense, since most MI's these days are written in Pidgin English by some slitty-eyed chap in Shanghai....... A 3A FCU will do nothing to protect a 20W fan from over current because its stalled current is no larger than its minute running current. The manufacturer recommends the use of an FCU, simply because he has no idea whether the fan will be connected to a lighting circuit or a power circuit. Isolation for rotating equipment is quite important in industrial settings - but not so for the average domestic, plastic fan.... Lucia.
Its amazing really. Impeller stall and stuff within the domestic environ and the supposed elevated current draw in a stalled state..
JP: in this instance it applies to low-power, shaded-pole motors with high resistance windings which are incapable of burn-out due to being dead-stalled. These motors will quite happily stay in a stalled condition - perhaps due to siezed bearings or a jammed impeller without activating the overload device..... Lucia.
Nice one Lucia..you obviously remember the asynchronous and shaded pole thing from what quite some time back. I agree with you fully on the stalled (locked) rotor with ref to the humble 4in/6in fan. There is about as much chance of the thermal operating in this state as throwing a snowball at the sun and hoping it does not melt. I hope people don't equate this also to locked brushed motors though..of course this is a different kettle of fish.
I don't really know Lucia..perhaps someone might think a WM motor in locked state might act the same as a locked shaded pole. But yes agree the OP was portraying a 4in fan and obviously I digressed a tad away from that.