Products > Test Equipment
Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter )
IanB:
--- Quote from: joeqsmith on April 29, 2023, 03:23:58 pm ---It's not something I would normally care about but with member Someone asking, I provided ASCC measurements for my home at a few locations which included my office. Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II. Maybe you do and can make a few measurements in your own home that we can use as a comparison.
--- End quote ---
To clarify, did you make these measurements by putting a load on the circuit and measuring the drop in voltage?
I think there would be an interesting difference here between countries. In the USA I commonly observe a voltage drop when loads are applied, for example the lights dim when a clothes iron or laser printer cycles on and off, or even when a neighbor's aircon unit starts up. I think everyone is probably familiar with this.
In the UK, I have observed no such effects. The electrical supply is often very stiff, such that the the first time I was in the USA and observed lights dimming I was quite surprised. Some reasons for this might include that in Britain the distribution transformer is commonly a large pad mounted unit that supplies a whole block of houses, therefore it will have a consequently low output impedance. Secondly, the distribution cabling under the street is correspondingly large, since it has to carry enough current for all the houses connected to it. Thirdly, in most houses the power circuits are rated to carry 32 A, even though individual outlets are limited to 13 A. Any UK electricians here can probably give an estimate of the typical short circuit current available in such an installation.
Fungus:
--- Quote from: IanB on April 29, 2023, 04:49:41 pm ---In the UK, I have observed no such effects.
--- End quote ---
In the UK they use a ring main system so there's probably less impedance to the sockets than your average USA installation.
https://en.wikipedia.org/wiki/Ring_circuit
joeqsmith:
--- Quote from: IanB on April 29, 2023, 04:49:41 pm ---
--- Quote from: joeqsmith on April 29, 2023, 03:23:58 pm ---It's not something I would normally care about but with member Someone asking, I provided ASCC measurements for my home at a few locations which included my office. Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II. Maybe you do and can make a few measurements in your own home that we can use as a comparison.
--- End quote ---
To clarify, did you make these measurements by putting a load on the circuit and measuring the drop in voltage?
--- End quote ---
Yes. I'm not sure how else these instruments would work. With mine, I can program the load. I provided that detail in the post.
--- Quote from: IanB on April 29, 2023, 04:49:41 pm ---I think there would be an interesting difference here between countries. In the USA I commonly observe a voltage drop when loads are applied, for example the lights dim when a clothes iron or laser printer cycles on and off, or even when a neighbor's aircon unit starts up. I think everyone is probably familiar with this.
--- End quote ---
I am not sure how many homes are fed from a transformer here. It's not the entire block. Maybe five homes. Mains are underground and transformers are on slabs.
Transformers are tiny as you would expect. There is a main feed line for these transformers. I believe then each home is fed as a star.
I have not seen (light bulbs do provide a simple, sensitive detector) any transients from the neighbors. In the house, the A/C, sump, clothes drier, oven and stove would be the largest loads but I don't see any effects from them. Even back when we were using incandescents. The problem here is that the grid is not stable.
--- Quote from: IanB on April 29, 2023, 04:49:41 pm ---In the UK, I have observed no such effects. The electrical supply is often very stiff, such that the the first time I was in the USA and observed lights dimming I was quite surprised. Some reasons for this might include that in Britain the distribution transformer is commonly a large pad mounted unit that supplies a whole block of houses, therefore it will have a consequently low output impedance. Secondly, the distribution cabling under the street is correspondingly large, since it has to carry enough current for all the houses connected to it. Thirdly, in most houses the power circuits are rated to carry 32 A, even though individual outlets are limited to 13 A. Any UK electricians here can probably give an estimate of the typical short circuit current available in such an installation.
--- End quote ---
I assume its all considered magical opinion and unicorns unless measured. :-DD While nothing to do with my kV DT830 demonstration, I wouldn't mine seeing what the people who are concerned, measure themselves, in their own homes.
AVGresponding:
--- Quote from: Fungus on April 29, 2023, 05:08:04 pm ---
--- Quote from: IanB on April 29, 2023, 04:49:41 pm ---In the UK, I have observed no such effects.
--- End quote ---
In the UK they use a ring main system so there's probably less impedance to the sockets than your average USA installation.
https://en.wikipedia.org/wiki/Ring_circuit
--- End quote ---
It's becoming increasingly common to use radials instead of rings. It's annoying for me because it's a lot harder to get two 4mm2 T+E into a back-box than two 2.5mm2, especially given the ever decreasing space available as they shrink containment down to save money >:(
Even worse when you have to pull it into conduit! :rant:
IanB:
--- Quote from: joeqsmith on April 29, 2023, 05:40:58 pm ---I assume its all considered magical opinion and unicorns unless measured. :-DD While nothing to do with my kV DT830 demonstration, I wouldn't mine seeing what the people who are concerned, measure themselves, in their own homes.
--- End quote ---
Fair enough. Which is why I would curious if any UK based electricians here could indicate what kind of prospective fault current would be measured at a typical UK 13 A wall socket? (It would be a range, obviously, but typical/min/max would be interesting.)
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