Leading on to… 433.20/202 where an allowance is made for the fusing factor of a 3036 fuse. If the fusing factor of a 1362 is at 1.9 it is fairly comparable so surely we must apply a comparable derating factor? This is where the wheels come off my bus if the answer is more than just… It doesnt protect against overload. Unfortunately this proves how difficult it is to tell the difference between counterfeit and genuine BS1362 fuses. The ASTA, BSI or Nemko approved symbols do not prove authenticity. Is there another factor at play here which I am missing? Or do I just have the wrong fusing factor!

If too large a current flows through a lead it may overheat or catch fire, making the main purpose of a domestic plug fuse to prevent fires due to large currents. NOTE 2: Protection in accordance with this regulation may not provide protection in all cases, for example, where sustained At the beginning, 100% of the heat generated in the live conductors is available to heat the cable. At 21 deg C, only 98% of the heat is available because the loss is 1/50 of the amount at the steady state. At 22 deg C, only 96% is available and so on. So looking at 1 deg C increments, it takes in fact 45 min to get to 69 deg C and you never quite get to 70 deg C. Please forgive me for having forgotten the calculus which I learned 45 years ago.Surprisingly the fuse does contain the sand filling required, most counterfeit fuses do not have any filling. The sand is required to control the breaking operation of the fuse. Without this filling material, the air within the fuse expands as the fuse wire melts and arcs, causing the fuse to explode, as demonstrated in our previous article on fake fuses. BS 1362 also specifies the fusing current as 1.9 times the rated current (I f = 1.9 I n). If the current exceeds the fusing current, the fuse must blow within 30 minutes. So a 13A fuse must blow within 30 minutes when carrying a current that exceeds 24.7A. I've been cogitating on the fusing factor of 1362 fuses (specifically 13A fuses) and how this correlates with the protection of a 1.5mm2 flexible cable. As ever I am hoping you can shine a light!

In the spirit of learning from my betters I will lay myself open to ridicule! I'm faintly terrified at having my life changed though! ? iii) the current (I2) causing effective operation of the protective device does not exceed 1.45 times the lowest of The fusein a plugis a deliberate weak link in a circuit which will 'blow' if an electrical appliance or extension lead draws too much current due to either an overload or a fault. The operating characteristics of a device protecting a conductor against overload shall satisfy the following conditions:Well a 13 A fuse will carry 13A all day, and may not blow in any sensible time even at 20-25A, depending on manufacturing tolerances and environmental temperatures. Simon's response correlates with what my understanding is telling me - which seems at odds with the pretty confident guidance/statements in the Beama guide. I find it quite common to see 13A 1362 fuses inline on 32A cooker circuits protecting 1.5mm2 flexes to ovens. Is this deemed acceptable even though the oven isn't strictly speaking a fixed load (fan motor etc.)? The manufacturing standard of these fuses is particularly poor. The fuse wire is simply trapped between the end cap and body. A genuine BS1362 fuse has the internal wire connected to an eyelet inside the centre of the cap.

Look at these curves and look at the ‘all blow’ right hand curve, vs the left hand ‘never blow’ limit for 13 and 3A fuses. The rated current or current setting of the protective device (In) does not exceed the lowest of the current carrying (Iz) of any of the conductors of the circuit, and

a-one and a-two and a-three.” for cranking time, And relax and cool for 15 -20 seconds before retry so average current is perhaps 20-30A. Breaking the fuse open confirms that these fuses are counterfeit. There is no sand filling. The quartz sand inside a genuine BS1362 is designed to control the rupture of the fuse wire within the ceramic body. The length of the fuse measures 24.91mm. A BS1362 fuse should have a length of 25.4mm with a tolerance of +0.8/-0.4mm.

This confusion (at least, in my mind!) seems to arise at least partially because 433.1.202 has been included completely unnecessarily, tempting one to think that BS3036 fuses are the only devices that require 'special attention/thought'. In reality, it is but just one example of a device with a 'fusing factor' which is not 1.45 (hence I 2 is not 1.45I n) , such that they could also have included (as another 'special case'), say, your BS1362 with a fusing factor of 1.9 (or whatever) ... or, better, not have this reg at all, and just let people work out I 2 for themselves.. The outcome of all this is to not worry about these minor domestic overload problems, as one can see from the normal use one sees, they rarely cause any trouble at all. Loose connections are the cause of problems, not overload of cables.It is a setting where a circuit experiences a current that is higher than the normal operating current.