Cable size and diversity

[JohnW2]

Like induction hobs, I believe?

Indeed so - I never suggested otherwise.

 

[morqthana]

A lot of my colleagues, gasmen, refuse to allow the concessions allowed in the REGS,

I imagine they also refuse to take any notice of what non-gasmen say about what should or should not be done wrt gas installation work.

They should be treated the same when pontificating about areas outside their expertise.

 

[FiremanT]

I imagine they also refuse to take any notice of what non-gasmen say about what should or should not be done wrt gas installation work.

They should be treated the same when pontificating about areas outside their expertise.

And that excuses them from charging pnters for work that is not neccessary?

I take it from yur commnt that you have a problem with a Gasman asking about electrics, or maybe you have a problem wih me asking for confirmation that I do or do not need a new CU plus 3 seperate radials to a kitchen, and that i should just take his quote as a neccessary evil?

 

[fixitflav]

That would be true for a purely reactive load, but such a load would presumably not consume any power!

Good point, and plugwash's comment.

Am I right thinking the induction hob works by creating eddy currents in the pan, hence resistive heating? It would be interesting to know how the current varies with voltage

 

[JohnW2]

Good point, and plugwash's comment.

Am I right thinking the induction hob works by creating eddy currents in the pan, hence resistive heating?

That is certainly my understanding - overall, an induction hob (downstream of the controlling electronics) will therefore presumably look largely as a resistive load.

It would be interesting to know how the current varies with voltage

Although, as above, the hob 'in itself' will probably appear as a largely resistive load, the voltage/current relationship in terms of the mains power supply will, as discussed, presumably depend crucially, and almost totally, on what the electronics chooses to do (not the least in terms of 'current limiting') ?

 

[FiremanT]

To be honest, that all got a bit techie - abob=ve me, I will admit

I have spoken to anther qualifed sparks, a colleague.

He insists that there is no DF on an induction hob, and it will need 10mm. He showed me someinternet searches to support that, but am struggling to find them now.

A frustrating factor is the inabiity to find installation instructions prior to purchase - gas stuff is freely available. Is there any such free sites for Bosch kitchen stuff?

I did find a Bosch help sheet. it says a 65mm gap is required between a drawer and the hob. Does this mean a physical gap above the drawer front - I dont see how that could be asthetically acheivable?

(it also says minimum 30mm worktop, but shows 20mm in the diagram!)

 

[trojanhawrs]

@FiremanT My mum's got a 7.4kw induction hob running off a 13amp plug top (not right but it's not popped yet). Run a cable suitable for a 32amp breaker and you'll be absolutely fine - it is worth checking the manufacturer's instructions though in case they specify lower overload protection for the oven - being an element though it shouldn't need it.

 

[morqthana]

And that excuses them from charging pnters for work that is not neccessary?

How do gasmen come to be charging customers for electrical work?

I take it from yur commnt that you have a problem with a Gasman asking about electrics, or maybe you have a problem wih me asking for confirmation that I do or do not need a new CU plus 3 seperate radials to a kitchen, and that i should just take his quote as a neccessary evil?

What bizarre suggestions.

My comment was to say that people should take as much notice of gasmen pontificating about how electrical work should be done as gasmen would take of electricians, or joiners, or etc pontificating about how gas work should be done.

 

[morqthana]

That is certainly my understanding - overall, an induction hob (downstream of the controlling electronics) will therefore presumably look largely as a resistive load.

Although, as above, the hob 'in itself' will probably appear as a largely resistive load, the voltage/current relationship in terms of the mains power supply will, as discussed, presumably depend crucially, and almost totally, on what the electronics chooses to do (not the least in terms of 'current limiting') ?

Isn't the name "induction hob" a bit of a give-away that it uses inductors, and therefore isn't a resistive device?

 

[morqthana]

He insists that there is no DF on an induction hob, and it will need 10mm. He showed me someinternet searches to support that, but am struggling to find them now.

The latter surprises me not.

No matter what technology a hob uses to heat the food, the food responds to the heat in the same way. When my steak hits the hot griddle pan it has no way of knowing if the pan was heated by induction, halogen, or an old fashioned ring. Or even gas. So if they all do the same thing, they must all do it to the same extent.

If diversity is OK for halogen or traditional hobs because they cycle on and off, don't run flat out all the time, then it's OK for induction hobs for exactly the same reasons.

 

[JohnW2]

Isn't the name "induction hob" a bit of a give-away that it uses inductors, and therefore isn't a resistive device?

That rather depends on what you mean.

As has been said, the 'heating process' itself will represent a very largely resistive load, the heat being generated by eddy currents flowing in the pan - it's the electronics driving it which may present the supply with something that doesn't behave much like a passive resistive load.

The same would be true of any other sort of ('traditional') hob (or any other heat-producing appliance). If the 'heating element' is connected directly to the power source, it will represent, and behave as, an almost totally 'passive resistive load'. However, if the element is fed from the source via an SMPSU, then 'anything is possible' in terms of its behaviour - for example, in the context we are discussing, it might result in increasing current being drawn at decreased supply voltages (so as to maintain power constant) - i.e. the opposite of what would happen with a passive resistive load.

 

[JohnW2]

If diversity is OK for halogen or traditional hobs because they cycle on and off, don't run flat out all the time, then it's OK for induction hobs for exactly the same reasons.

Quite so. One can't defy the Laws of Physics. The concept of diversity could only be less applicable to induction hobs than to 'traditional' ones if they were less efficient in heating the contents of the pans - which is probably the opposite of the truth.

In fact, if I understand correctly, not only does the standard concept of diversity apply equally to induction hobs, but I think it is often, in some senses, actually hard-wired into induction hobs, particularly those designed to be 'plugged in' (in that total current consumption is limited to, say, 13A, even if the current would have been greater than that at times with purely thermostatic control?

 

[FiremanT]

How do gasmen come to be charging customers for electrical work?




What bizarre suggestions.

My comment was to say that people should take as much notice of gasmen pontificating about how electrical work should be done as gasmen would take of electricians, or joiners, or etc pontificating about how gas work should be done.

I assume , though, that you are referencing me?

I have not “pontificated” , I have asked for clarification.

Ot does it seem like pontification to suggest that wildly varying responses and claims indicate that some individuals have got it wrong?

Or is it the case that any answer or view is legitimate as long as it is from a member of the same trade?

 

[FiremanT]

@FiremanT My mum's got a 7.4kw induction hob running off a 13amp plug top (not right but it's not popped yet). Run a cable suitable for a 32amp breaker and you'll be absolutely fine - it is worth checking the manufacturer's instructions though in case they specify lower overload protection for the oven - being an element though it shouldn't need it.

I would love to check against the instructions- but it seems difficult to get INSTALLATION instructions before selecting an appliance. In fact, I know what we want, model wise, but cannot get the details ahead of purchase.

 

[EFLImpudence]

I have spoken to anther qualifed sparks, a colleague.

Another?

He insists that there is no DF on an induction hob, and it will need 10mm.

Clearly nonsense on both parts.

Are they not more efficient than traditional hobs?
Doesn't that mean they use LESS power? So why would they need MORE?

Even IF there were no DF on an induction hob, why would 10mm² be required?