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When i open the plastic casing of electric switch and socket normally used in household like (250 V AC 16 A Switch , 250 V AC 13 A Socket) then i found different shaped copper bar. copper rod, copper sheet. Shape of these items are not uniform so area is different. So for a certain voltage and current how can i calculate the proper thickness as well as the copper grade. For a cable diameter is uniform and in web there are lots of information how to calculate the diameter of wire but for these copper items i did not found any good reference where i can study.

Thanks in advance and sorry for this stupid question

  • \$\begingroup\$ My educated guess is that the shape of the diameter does not really matter, so you should be able to use the diameters given for copper cables and compare them to the cross-sectional area of the connections in the socket. The more important issue may be the materials would be brass more often than copper I think. \$\endgroup\$ – 0x6d64 Oct 4 '16 at 19:46
  • \$\begingroup\$ Remember that there is a cost associated with processing the metal into the required shapes, and it may be that using an over-sized piece of copper is cheaper than cutting it to the minimum size permissible for the current. \$\endgroup\$ – Andrew Morton Oct 4 '16 at 19:47
  • \$\begingroup\$ May I ask a question... why do you need it? If you can explain your target probably we will be able to give you more precise advice. And question actually is not a stupid one. I guess there're a number of patents filed in the area of your interest. \$\endgroup\$ – Anonymous Oct 4 '16 at 19:50
  • \$\begingroup\$ According to your concept i need to consider the lowest thickness/ area to calculate the current rating of brass items, is it ?? @0x6d64 \$\endgroup\$ – rumman Oct 4 '16 at 20:15
  • \$\begingroup\$ I am going to work with these products that's why i need to know in details.@ Anonymous \$\endgroup\$ – rumman Oct 4 '16 at 20:18

I have never designed a switch or socket, but given the task my starting point would be to look up the appropriate national or international standard for switches and sockets. In Europe this is EN 60669-2-6.

An important factor will be the permissible temperature rise of the internal parts when the switch or socket is used at its maximum current. This will be given in an national standard. From the temperature rise you can work out the maximum resistance of each part. This is quite difficult because you don't know the thermal conductivity of the part in degree C per Watt. There are CAD programs that can simulate this, or you could work it out by experiment.

From the maximum allowed resistance, and the length of the part, you can then work out the cross sectional area of the copper or brass used to make the part. You would also need to take into account the resistance of each weld or rivet used to hold the parts together. Finally you would test the plug or socket in the way described in the standard and adjust your cross sectional areas accordingly.


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