Usually best to fit the cooker connection unit to the side of the cooker. (e.g behind a cupboard)
cooker & hob connection
- Thread starter propertydev83
- Start date
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All circuits have (or should have) protection from an MCB, RCBO or fuse in the CU, some items may be connected via an additional FCU, and everything plugged into a socket with a standard BS1363 "13A" plug will be protected by a fuse in that plug - so, in those senses, every load should have at least some 'external' protection (even if only that in the CU).
As for internal protection, that will only exist when the manufacturer of the appliance or equipment feels the inner workings of the appliance/equipment require a degree of protection greater than (i.e.'lower rated than') that which will normally be provided by the protection of the circuit to which it is connected - or, where appropriate, the fuse in a plug or FCU. In the cases of some appliances (e.g. cookers), it may be felt that the circuit's protection will give adequate protection to the 'works' of the appliance. However, this is one reason why a manufacturer may sometimes specify a maximum fuse/MCB rating for the circuit supplying the item - if they feel that a higher rating than that might not give adequate protection to their appliance. However, as being discussed here, many people feel that they really should include their own, adequate, internal fusing if that is the case, rather than rely on the circuit's protection.
In the opinion of the manufacturer, yes - but, as you will have seen, electricians may well feel that such fusing down would really be unnecessary - but, as also discussed, if you don't do that then manufacturers may try to argue that their warranty had thereby been invalidated. If they don't state a maximum size of MCB/fuse, then this obviously is not an issue. It can sometimes be difficult to work out whether instructions are specifying a 'required' size of MCB or merely indicating the (minimum) supply that would be adequate to power the appliance.
Kind Regards, John
That all makes sense. Thanks again John, and all others.
Just a matter of finding the right oven and hob for the right prices now. Gotta keep searching.
Just a matter of finding the right oven and hob for the right prices now. Gotta keep searching.
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I was busy and posted in haste which is why I didn't make myself clear.
A big part of safety testing of electrical appliances, including lighting, is applying faults to ensure that an appliances fails safely.
Amongst other things motor rotors are locked, ventilation slots are blocked, components are short or open circuited. Forseeable misuse is anticipated like running water heaters empty, covering heaters with blankets etc etc.
During the fault testing, the appliance, essentially, must not catch fire or present a risk of electric shock (there are specific temperature limits and tests performed to verify this).
Another criterion is that during or after the test, fuses or MCBs in the fixed wiring must not open. This is checked by monitoring the supply current during testing. If the supply current rises too high, the product fails and the manufacturer must correct the problem by either fitting internal over-current devices or by some other modification.
In other words, the manufacturer can not rely on overcurrent protection devices in fixed wiring to ensure that his product remains safe when a fault in his appliance occurs.
Hope this is a little more clear.
A big part of safety testing of electrical appliances, including lighting, is applying faults to ensure that an appliances fails safely.
Amongst other things motor rotors are locked, ventilation slots are blocked, components are short or open circuited. Forseeable misuse is anticipated like running water heaters empty, covering heaters with blankets etc etc.
During the fault testing, the appliance, essentially, must not catch fire or present a risk of electric shock (there are specific temperature limits and tests performed to verify this).
Another criterion is that during or after the test, fuses or MCBs in the fixed wiring must not open. This is checked by monitoring the supply current during testing. If the supply current rises too high, the product fails and the manufacturer must correct the problem by either fitting internal over-current devices or by some other modification.
In other words, the manufacturer can not rely on overcurrent protection devices in fixed wiring to ensure that his product remains safe when a fault in his appliance occurs.
Hope this is a little more clear.
On the surface it does seem fair to say that a manufacturer stating that their unfused appliance should only be used on a circuit with a maximum MCB rating are just using that as a reason to invalidate some warranties. If such a product has a fault, and was being used with an MCB higher than the specified maximum rating, the MCB being used would certainly NOT be to blame? But they can argue their instructions were not followed?
That all makes sense. However, apart from the jammed motor rotor, or secondary consequences of heat damaging components or electrical insulation, the scenarios you mention would not normally be expected to have any 'electrical' consequences (i.e. an 'overload' situation).
This is obviously the bit we are are discussing. Is it not possible for the manufacturer to argue that their product remains safe, even in the absence of internal fusing, if they insist that the circuit feeding the appliance is protected by a sufficiently low-rated OPD? ... or does the test require that the appliance remains safe even if the supply is 'unlimited' and not protected by an OPD?
Kind Regards, John
There is obviously no way that having a high MCB rating can cause a fault to arise in an appliance - unless/until a fault has already arisen, there is obviously no way that an appliance can 'know' anything about the rating of the MCB. Hence, any manufacturer who claims that using a MCB with a rating above the maximum they specify has caused a fault is obviously talking nonsense - but many of the general public would not have the knowledge or inclination to argue if the manufacturer was trying to use that excuse for not honouring a warranty claim. Having a 'too-high-rated' MCB (in the absence of internal fusing in the appliance) might, of course, increase the consequences of a fault (notably those due to heat and/or fire), and hence might affect the warranty claim (particularly as regards amount paid up), but doesn't alter the fact that a (probably warranty-covered) fault arose in the first place.
Kind Regards, John
According to the standards we test to, it is not acceptable for a manufacturer to require the installation of external protective devices to ensure the safety of their product. That is to say, the appliance should remain safe if the supply is unlimited. I presume the rationale is that the appliance must remain safe regardless of the rating of the circuit it is connected to.
That all makes sense - but it seems to make even more nonsense of the fact that they very often do state external OPD requirements. If their products are required to be safe without any external protection, do they therefore do this only to provide a (pretty lame) excuse for disputing warranty claims?
Kind Regards, John
This was exactly my train of thought. Their claim is illogical, but I can certainly seeing companies trying it with the average consumer.
Product required to have its own internal safety precautions, even if there is totally unlimited supply > Manufacturer complies with requirements > Manufacturer states to customers that supply must be "limited" for the safety of the product?! Yeah okay...
Indeed. However, as I said, I fear than many (most?) consumers probably lack the knowledge, inclination or resources to challenge a claim that failure to follow the instructions (as regards 'external protection') has invalidated a warranty claim!
If I wanted to give a little benefit of the doubt to the manufacturers, I suppose I might consider that 'safe' is being used in different senses. Compliance with the requirement that the appliance is 'safe' (does not produce a hazard under fault conditions) does not necessarily preclude the possibility that, once a fault has developed (obviously no fault of the external protection), the extent of the consequent damage to machine may be reduced if the stated external protection were in place. Hence, whilst a manufacture could not sensibly claim that the absence of external protection had caused the fault, they might be able to argue that it had resulted in greater damage to the appliance - so might use that to limit how much they would pay out.
Kind Regards, John
Extractor fans apart, I would say that the requirements are usual compatible with what an electrician would expect - although there will be exceptions which may be written by those with insufficient knowledge.
This should not be the case but one recent example discovered that the manufacturer's instructions had been written by the marketing department.
There is then the unclear distinction between instructions and information.
As for ovens, as I have stated before, there will be stated minimum supply for proper operation or maximum fusing requirements presumably because of the cable supplied, but with no overload this is not really necessary although without test equipment may be prudent.
There are inconsistencies in manufacturer's instructions/information which seem to enable fitters from the sales outlet to frequently state that they cannot connect the appliance.
Should a manufacturer state that, for example, an electric shower must have a 40A OPD, RCD and 6mm² cable, are these instructions or information and does this preclude it being supplied with other acceptable arrangements which may already be in place?
This should not be the case but one recent example discovered that the manufacturer's instructions had been written by the marketing department.
There is then the unclear distinction between instructions and information.
As for ovens, as I have stated before, there will be stated minimum supply for proper operation or maximum fusing requirements presumably because of the cable supplied, but with no overload this is not really necessary although without test equipment may be prudent.
There are inconsistencies in manufacturer's instructions/information which seem to enable fitters from the sales outlet to frequently state that they cannot connect the appliance.
Should a manufacturer state that, for example, an electric shower must have a 40A OPD, RCD and 6mm² cable, are these instructions or information and does this preclude it being supplied with other acceptable arrangements which may already be in place?
I would have thought that if the manufacturer uses the word "must", at least in their eyes it is intended as 'instruction'. Where it is a sensible or rational instruction is a different matter. It would obviously be particularly ridiculous if, with your example, they claimed that there had been a failure to comply with their instructions if there were a 40A OPD and an RCD, but the cable was larger than 6mm² !!
Kind Regards, John
yes, my point - and also with larger cable may be a higher rated MCB.
Also, as I have said before, is it in a shower manufacturers remit to demand an RCD.
I know it is a good idea and you would not want it to be without but is it the manufacturers responsibility when it is nothing to do with their product.
Also, as I have said before, is it in a shower manufacturers remit to demand an RCD.
I know it is a good idea and you would not want it to be without but is it the manufacturers responsibility when it is nothing to do with their product.
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