Induction hob cable

[ban-all-sheds]

Then you are stuffed, as a cable that does not exceed the terminal size has to be used.

Can you please let us know how many times, and by how many separate people, you have to be told that you are wrong before you accept that you are and stop making daft pronouncements, so that we can get on with the job of reaching that threshold and putting an end to your nonsense.

 

[ban-all-sheds]

Bad analogy. It has been brought to your attention by others that a ring has two 27A cables, giving 54A with a 32A mcb.

Might not. Might have two cables rated at only 20A.

Also, will you please do the calculations and show (probably with the aid of diagrams) under what circumstances you can simply multiply the rating of the cable by two and declare that to be the rating of the entire ring.

Also, no appliance can be connected to the ring with a fuse larger than 13A.

And what if you have two 13A loads connected, and the circuit cable is only rated at 20A?

What if you have three such loads connected?

You can plug in a 3kW heater to every socket but the 32A mcb cuts out. Diversity is used on a ring.

Diversity is used wherever the loading is variable, and a simplistic "add up everything possible" approach is unrealistic. So that would include cooking appliances where thermostatic cycling means that adding up all of the components in the appliance is unrealistic.

A proper installation has high power appliances on their own circuits & mcb, etc.

A proper installation is properly designed.

 

[ban-all-sheds]

You are stuffed it you want to fit a cable larger than what the appliance terminals can take for sure. So you fit a cable that the terminals can accommodate.

But what if that size is "too small" because you do your sizing without any diversity?

 

[ban-all-sheds]

But you need fuses and mcb's about an installation to ensure cables are protected and do not get too hot being a fire risk.

Protected from what? Overloads or faults?

I would use the diversity factor with caution in high-rise flats. Someone on this thread said the diversity factor dictates that a 2.5mm cables can be the final flex cable to a 7.4kW induction hob. This when the diversity formula has to be treated with caution.

Someone on this thread said the diversity factor dictates that a 2.5mm cables can be the final flex cable to a 17A load?

With 2.5mm² in free air, you could have a multiplier in your diversity calculation as high as 0.9 instead of 0.3. Please explain why 0.3 has to be treated with caution.

 

[hard-work]

What you seem to be missing is the fact that the 2.5mm² cable would have to be adequately protected by an appropriate MCB.

If a 6mm cable from the CU a 40A mcb then a fuse to protect the 2.5mm cable rated at 25A. So tat is whne they go for cable all the way that can handle more than 40A, so as not to fit fuses in the hob line. It is simpler and cheaper usually and quicker of course.

 

[JohnW2]

If a 6mm cable from the CU a 40A mcb then a fuse to protect the 2.5mm cable rated at 25A. So tat is whne they go for cable all the way that can handle more than 40A, so as not to fit fuses in the hob line. It is simpler and cheaper usually and quicker of course.

The sensible thing to do in that situation is to change the MCB to a 25A one, since a cable run partly in 6mm² and partly in 2.5mm² cannot carry more than 27A (after diversity, where appropriate) at most.

If you want to make this discussion even more complicated (and probably even more contrary to your views), there is an argument that some cooking appliances (simple, 'old fashioned' ones with just resistive elements and no fan) are not capable of creating an 'overload', so that no 'overload protection' is required at all. In such a case, one would only need 'fault protection' (protection against short circuits etc.) and, depending on the length of the cable and other factors, 2.5mm² cable might be given adequate fault protection by a 40A, or even higher rated, MCB.

Kind Regards, John

 

[ban-all-sheds]

If a 6mm cable from the CU a 40A mcb then a fuse to protect the 2.5mm cable rated at 25A.

Will you please explain why you think that fuse is needed. What kind of overcurrent events do you think it will prevent?

 

[aptsys]

partly in 2.5mm² cannot carry more than 27A (after diversity, where appropriate) at most.

What happens if you put 28A down some 2.5mm² cable?

 

[stillp]

What happens if you put 28A down some 2.5mm² cable?

For how long, and what installation method?

 

[hard-work]

JohnW2, interesting about the old elements. I was thinking about a long length of cable to a hob which has a drop because of the length and which already has a 40A mcb. At the hob a fuse could be fitted to protect the 2.5mm.

 

[JohnW2]

JohnW2, interesting about the old elements. I was thinking about a long length of cable to a hob which habe drop because of the length and which already has a 40A mcb. At the hob a fuse could be fitted to protect the 2.5mm.

As I said, if the load consists of just resistive elements (which, to all intents and purposes cannot produce an overload) you would actually not need any overload protection for the cables (either the 6mm² or 2.5²mm) at all. All you would need is fault protection and, particularly given the fact that most of the cable run in 6mm², reducing to loop impedance of the circuit) I would think that a 40A MCB would very probably prove to be more than adequate to provide fault protection for the 2.5mm² cable.

Kind Regards, John

 

[ban-all-sheds]

Hard-work - can we take it from your silence that you have not the slightest intention of even trying to explain why you said some of the things you have about cable sizes, current capacities, overcurrent protection etc?

Would you like to give us a hint as to whether you would prefer us to think that's just because you can't be rsed, or it's because you don't have a clue what you are talking about?

 

[ban-all-sheds]

At the hob a fuse could be fitted to protect the 2.5mm.

So you'd fit it at the end of the run of 2.5mm, not at the start? How would that protect the cable?

And how, practically speaking, would you install a fuse there?