Double sockets

[JohnW2]

I strongly suspect that if you increase the voltage you will eventually reach a point where heating effects are observed even with no load attached.

Of course, but it would take a mighty high voltage to get any measurable current, let alone enough to produce significant heating through the insultaion of an intact socket.

In context, it was the other way around we are talking about - and I certainly can't think of any reason on earth why a current-based temperature rise test should be in any way affected by use of a voltage less than the 'rated' one - can you?

Kind Regards, John

 

[JohnW2]

Im thinking that a lot of the BS1363 requirements are pretty daft and don't actually represent real world usage of these sockets, which is what we all really want to know about.
I think I'll stick with my rig. If I can i'll try and incorporate some sort of temperature probe to it.
I will continue to use real plugs with 13A fuses and shrouded pins connected to either 1.25mm² or 1.5mm² 3 core flex, as could feasibly be found in a real life situation.

I think that all makes total sense, for us.

I still think that a load of 26A on a double socket is hichly unlikely, espacially in a domestic property, but I'll go with it for the sake of this experiment.

Pretty unlikely, domestically, for substantial sustained periods of time, I'd certainly agree. Indeed, in the real world, even a sustained load of 13A from one 'socket outlet' for a substantial period of time (several hours) is probably very uncommon, so 2x13A for 'hours' would be extremely unlikely.

I'm not sure what voltage I'll use yet. I'll have to see if I can sort out a 13A load at ~50VAC. If not I'll stick with 230V as I can easily get an exact 13A load using a dimmer to tweak things.

Depending what's in your 'boxes of tricks', I suspect that it might be quite hard to find a suitable 13A load for a 50V supply, whereas if you stick to 230V, you obviously have the whole spectrum of domestic appliances to choose from.

I look forward very much to seeing your results.

Kind Regards, John.

 

[ban-all-sheds]

Of course, but it would take a mighty high voltage to get any measurable current, let alone enough to produce significant heating through the insultaion of an intact socket.

Just wait until it starts arcing - you'll get significant heating then.

 

[ban-all-sheds]

• 
  

http://www.theiet.org/publishing/wi.../pre14-BS7671-amd1-ring-circuits.cfm?type=pdf

 

[JohnW2]

• 
  

http://www.theiet.org/publishing/wi.../pre14-BS7671-amd1-ring-circuits.cfm?type=pdf

Thanks; it's always nice to have some facts and figures, and insights into thinking behind regulations.

I have to say that the Electrical Assocation's figures for average 'Total Domestic Electricity Demand' are really far less useful than one might think. Although the article says of these figures "...They do however give an insight to the likely half hour demands of ring circuits.", I really don't think that's true in any meaningful sense. The figures are obvioulsy averages across many households, which has no real meaning in terms of the loading on any particular household's ring circuits. The peak 'average demand', at about 18:00 for a 5-person household, is only around 1.5 KW - and that average is inevitably made up of many households with very low (even zero in some cases) demand at the time and some households with very high demands at the same time. Without other statistics in addition to the average, there's really no way one can conclude anything particularly useful about ring circuit loading in any one household.

Kind Regards, John

 

[ricicle]

The peak 'average demand', at about 18:00 for a 5-person household, is only around 1.5 KW

It's more like 2kW...

 

[JohnW2]

The peak 'average demand', at about 18:00 for a 5-person household, is only around 1.5 KW

It's more like 2kW...

It actually looks like about 1.7 KW on the graph to me, but the actual figure is irrelevant. Whether the peak average for 5-person households is 0.5, 1.5, 1.7, 2 or 5 KW, my point still remains that you cannot conclude anything useful about individual household's circuit loadings without at least some more information (e.g. regarding the between-households variability).

Kind Regards, John.

 

[Stoday]

The Peak Demand figures were produced by the Electricity Association, which ceased to exist after 2003. The load research work that the EA undertook also ceased. The only work on loadings is now done by Elexon and that for load profiling only Click for profiles. The values for the domestic load are very similar to Profile Class 1 (Domestic Unrestricted).

The demand value of PC1 is the value at the National Balance Point, a theoretrical point on the Grid. If you apply the appropriate diversity factor, you can create the value at each of the voltage and distribution system levels.

For example, the diversity to the meter in a house (on average) is 5, so the MD for a 1.1kW demand at NBP is 5.5kW.

Similarly, the diversity to the LV feeder from the distribution substation down the street is 3.12, so the extra demand on the feeder of adding a house is 3.4kW. The extra demand on the substation is 2.1kW.

To understand these numbers, you should be aware that the definition of maximum demand for distribution purposes is "twice the number of kWh measured in any half hour", i.e. the demand is averaged over an integration period of 30 minutes.

That makes sense for distribution plant with its high thermal capacity, but not for a household and especially not for an individual final circuit within a household. The MD for a household is the near instantaneous MD, only excluding transient loads of switching on incandescent lights and starting small motors.

If you've followed all this and not lost the will to live, you will now understand why a MD of 1.1kW at NBP is compatible with a household MD of 18kW.

 

[JohnW2]

....That makes sense for distribution plant with its high thermal capacity, but not for a household and especially not for an individual final circuit within a household. The MD for a household is the near instantaneous MD, only excluding transient loads of switching on incandescent lights and starting small motors.

Indeed. Figures for demand averaged over many households are of crucial importance and value to the producers and distributors of electricity but, as I said, are quite useless in terms of an individual household - where 'the demand is the demand', regardless of the value of the average across many households.
If one had some information on the between-household variation in demand (ideally standard deviation, but even range would be better than nothing) at each time point, one could at least make some probabilistic statements about individual household demand (e.g. 'the peak demand in 95% of households at time point T will be less than XX Amps').

Kind Regards, John

 

[stillp]

RF, any results from your testing yet?

 

[ban-all-sheds]

He's still busy on it in his shed.

 

[RF Lighting]

I've done a couple of tests so far but I'm working away a lot at the moment so haven't really had much time to spare on it.

I'll post my findings on here as soon as I get chance.

 

[mikhailfaradayski]

c'mon RF, shake a leg!!

I bet John and stillp are sitting on the edge of their seats.

I imagine the results of your testing might mean they can squeeze another 6 or 7 pages out of this topic.












(BTW, told you all it was very simple )

 

[JohnW2]

I bet John and stillp are sitting on the edge of their seats. I imagine the results of your testing might mean they can squeeze another 6 or 7 pages out of this topic.

well, if it's pages that you want, the last four posts (plus this one) have probably added half a page, without saying one word about the actual topic

Kind Regards, John

 

[mikhailfaradayski]

I bet John and stillp are sitting on the edge of their seats. I imagine the results of your testing might mean they can squeeze another 6 or 7 pages out of this topic.

well, if it's pages that you want,

ooooh, no, its not a question of me wanting anything, but this post might help you get to 12 pages

the last four posts (plus this one) have probably added half a page, without saying one word about the actual topic

Kind Regards, John

OOI, i wonder what the record is for longest thread is in this forum. My guess is you're at least half way there