220v. 230v, 240v, 250v?

[LastManOnline]

There are lots of ring circuits in Ireland. Maybe they want deaths and fires by reducing protection.

With respect John. It would be appreciated if you concentrate on electrically analysing the questions being raised rather than making throwaway / unfounded comments.

 

[John-SJW]

With respect John. It would be appreciated if you concentrate on electrically analysing the questions being raised rather than making throwaway / unfounded comments.

If you take the fuse out of the plug when on a ring, you will get fires, as an essential safety point has been removed. The farsighted men in 1942 who thought of the fuse in plug, and then regulated for it, were brilliant. We have the best. Why change what does not need changing.

 

[LastManOnline]

In summary, I do not think it was the intention of Bosch to imply that a 3.7kW load may be supplied via a 13A plug,

Got an update from Bosch this morning stating that it's hob will "not draw more than 3.7kw when being used".So this would imply a current of 15.5 amp in the UK and 16 amp in ROI on its 13 amp plugtop when the hob is on full load.

The figures don't look great. We are on the wrong side of the plugtop rating. However, (going to stick my neck out here a little). I would have no concern about installing one of these in my own home as my current Induction hob (which by coincidence only ever has 2 rings on at any one time) is constantly cycling in and out and in reality the average load is under 13 amps (probably a, few amps under after initial startup).

Would I install one in someone else's home?. Unlikely unless there is a separate circuit. This particular appliance seems to fall between a rock and a hard place according to our regs. Can't see an inspector being pleased to see it being plugged in.

Bosch I think we're more than a little careless in the way they wrote their instruction Manuel.
Secondly, it was clear to me that the "service personnel" (who were very pleasant to deal with) were struggling a little in answering technical questions. Not their fault.

 

[John-SJW]

Got an update from Bosch this morning stating that it's hob will "not draw more than 3.7kw when being used".

So, what is it set to, if it is settable, as it has a 13A fuse?
Is this a continuous 3.7kW, or a spike?
Something tells me they do not know enough about their own product.

Out of interest, my Smeg induction hob states 7.2 kW. It can be wired 3 or single phase. I assume the 7.2kW is for 3-phase connection. I put on an amp clamp, then put all rings on full with pans full of cold water, on the P setting. It was drawing only 21.46 amps at 247v, which is about 5.3 kW, way below the max of 7.2 kW they state.

 

[LastManOnline]

So, what is it set to, if it is settable, as it has a 13A fuse?

As mentioned in earlier posts. A 13 amp fuse will take 15 amps for a significant period

Out of interest, my Smeg induction hob states 7.2 kW. It can be wired 3 or single phase. I assume the 7.2kW is for 3-phase.

No. 7.2kw is also suitable for single phase. They have 3 phase on the continent in domestic dwellings and that's why the hobs are configured to be connected both ways

put on an amp clamp, then put all rings on full with pans full of cold water, on the P setting. It was drawing only 21.46 amps at 247v, which is about 5.3 kW, way below the max of 7.2 kW they state.

You are probably getting an average as the rings cycle in and out of full power

 

[John-SJW]

As mentioned in earlier posts. A 13 amp fuse will take 15 amps for a significant period

No. 7.2kw is also suitable for single phase. They have 3 phase on the continent in domestic dwellings and that's why the hobs are configured to be connected both ways

You are probably getting an average as the rings cycle in and out of full power

I know it can. I forget how long. Any offers from the group? I recall a 13A fuse blows at about 17A after about an hour. So for intermittent use that is fine, not for a continuous load like a space heater.


I put the large pans of cold water on each ring, then all on the highest P setting, then observed the clamp meter. No switching in and out at that point as all rings were on full belt.

 

[John-SJW]

Look at at a plug. It always says 13A, 250V. That is 3.2 kW.

 

[timhoward]

I know it can. I forget how long. Any offers from the group? I recall a 13A fuse blows at about 17A after about an hour.

If this graph is true a BS1362 13 amp fuse won't blow at all until over 20 amps and at least 2 hours.

 

[Julie.]

The characteristic curve isn't quite right or the markings are wrong, the characteristic must become asymptotic at a value no greater than 19.5A for a 13A fuse, or it wouldn't comply with the 1.5 rule going back to the 14th for close protection, and they are the same fuses now.

It could take up to 4 hours to operate of course.

 

[timhoward]

The characteristic curve isn't quite right or the markings are wrong, the characteristic must become asymptotic at a value no greater than 19.5A for a 13A fuse, or it wouldn't comply with the 1.5 rule going back to the 14th for close protection, and they are the same fuses now.

It could take up to 4 hours to operate of course.

Thanks Julie. I've never found a good graph for this question...

 

[telectrix]

Look at at a plug. It always says 13A, 250V. That is 3.2 kW.

250V is the voltage rating of the plug assembly. nothing to do with calculating the wattage. the current rating is 13A, whether the voltage is 250V , 230V, or even 110V.

 

[LastManOnline]

14.09 amps @ 220v
13.47 amps @ 230v
12.91 amps @ 240v
12.4 amps @ 250v

John was correct with his calculations (in connection with the Bosch hob) though more by accident than design. It's down to the fact the hob (a, resistive load) has a power limiter built in to it, causing the hob in effect to behave like an inductive load. So a reduced voltage in this(very unusual case) would in fact lead to the current rising until the power limiter kicks in.

This latest contribution from me has the potential to be included in the..... "that's another 60 seconds of my life I will never....." but I thought I, d share it anyway.

 

[Lucien Nunes]

But an induction hob is not a resistive load, it's a CW radio transmitter inside a feedback loop. Even without the limiting function its behaviour is arbitrary and whatever the makers want it to be. I don't know whether the default behaviour of domestic induction hobs approximates to constant power.

And surely the limiting function sets the maximum current, not power? Granted, as far as the user experience is concerned the power is being limited, but it makes no sense to throttle the current below the circuit rating when the voltage is high.

 

[LastManOnline]

But an induction hob is not a resistive load, it's a CW radio transmitter inside a feedback loop. Even without the limiting function its behaviour is arbitrary and whatever the makers want it to be. I don't know whether the default behaviour of domestic induction..........

Well, at least I got the bit about...... "That's another 60 seconds of my life......." correct?

 

[static zap]

Once you add intelligence to an appliance , you really need to know you
way around the software ,and overload protection circuits.
( and HOPE it remembers its configuration/settings faultlessly )
.. I think you can have things , Too conductive for this technology ..

 

[John-SJW]

John was correct with his calculations (in connection with the Bosch hob) though more by accident than design.

I got them right. As I just pressed the right buttons.

 

[John-SJW]

The characteristic curve isn't quite right or the markings are wrong, the characteristic must become asymptotic at a value no greater than 19.5A for a 13A fuse, or it wouldn't comply with the 1.5 rule going back to the 14th for close protection, and they are the same fuses now.

It could take up to 4 hours to operate of course.

Thanks.

Now going back to the 3.7kW Bosch hob on a 13A plug. At 220v to 250v it will draw below the 19.5A (1.5) limit of the 13A fuse. They must have taken diversity into account, as would a hob be on full belt for 2 hours? How often would the hob run over 13A even with a big Christmas dinner? If it was running over a 13A current draw, for how long on average?

So the makers have deemed that a 13A fuse can cope with a 3.7kW hob. As it is not a portable appliance I would question if it should even be on a plug - but that is another point.

 

[static zap]

a 13A fuse can cope with a 3.7kW hob.

There is a big gap between COPE , and good design !.
( Wait n see how many RCF are damaged charging cars as well in winter )
... All weak points will be discovered ... without Arc thingies !

 

[John-SJW]

There is a big gap between COPE , and good design !.
( Wait n see how many RCF are damaged charging cars as well in winter )
... All weak points will be discovered ... without Arc thingies !

Well they will have to install a proper EV charger with a dedicated 6mm cable.

13A sockets are for portable appliances which do not draw a sustained high current. To fully charge an EV with a 13A socket will Take a few days - not what the socket and plug were designed for.