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Dad, What's a Circuit?

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Well son that a long story.


In my dictionary a circuit is: roughly a circular route, a track for motor racing in the U.K., a regular journey around a district by a judge to hear cases, a system of conductors and components forming a complete electrical path. It comes from the Latin word "circuitus." (No doubt related to the Latin word "circulus," which means circle.


I can see why ebee's friend considers two lighting circuits connected to just one M.C.B.to be two circuits connected together. Two individual circuits connected in parallel in fact.


When we are taught about electrical circuits at school we are told that the circuit starts at the source, which could be a battery terminal , continues to a load, which could be a light bulb, through the load, and then returns back the the battery's second terminal. Or the same arrangement could be made using a transformer's secondary winding.


But B.S. 7671 defines a circuit as: "An assembly of electrical equipment supplied from the same origin and protected by the same overcurrent protective device(s)."


So, a 1.0 mm2 T&E cable supplying lighting connected to a 6 Amp M.C.B. is a circuit. In B.S. 7671 land if a second 1.0 mm2  T&E lighting cable is added to the same M.C.B. there is still only one circuit even though one lighting circuit may supply upstairs in a house, and the other downstairs. Or perhaps originally the two originated from two separate M.C.B.s.


So in B.S. 7671 land, 1 circuit plus 1 circuit = 1 circuit. How could it be any different?


I personally, still though, prefer to call that situation two circuits connected in parallel.


Z.

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    I am NOT trying to muddy the waters Z, I am pointing out the statement in BS7671 definitions of a CIRCUIT is, a collection of wiring which starts and ends at the CPD. However, this definition is not that of a true electrical circuit, which is a network of connections between a number (many in electronic items) including sources of power (possibly batteries) which may be almost beyond comprehension in the CPU of your computer. How the electricity actually works is, in reality, unknown, the velocity of charge carriers matches nothing physical to the velocity of propagation and therefore must be faulty, despite hand waving of the "Group versus phase velocity" and other nonsense. The only information we have comes from equations and data that cannot be verified, the very low figure of a few m/sec or less come from a string of assumptions as long as your arm, and the relativistic velocity calculation is not supported by the accelerating potential, the answer is, therefore, we don't know how electricity works. Inside your computer chip signals travel and cause actions at about half the speed of light, that cannot be electrons (insufficient accelerating potential) therefore must be something else, or quite possibly our understanding of electrons is completely incorrect, which is quite possible. However, this is not the place to discuss this further although I would be happy to do so elsewhere.


    What I am saying is that your idea of an electrical circuit is excessively simplified for Engineering as a whole, if it helps you then fine, I don't mind, but please don't try to tell everyone else this is as far as it goes, it is not by a million miles, the reality is infinitely more complex. Consider this, your brain and nervous system appear to operate by electricity and therefore are electrical circuits. Is your brain part of a complex system or a group of individual circuits (by your definition) which presumably means that they can be isolated and adjusted. Do you think that is the view of a neurosurgeon? Everyone who has tried has found that such results in massive damage to function.
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  • 0
    I am NOT trying to muddy the waters Z, I am pointing out the statement in BS7671 definitions of a CIRCUIT is, a collection of wiring which starts and ends at the CPD. However, this definition is not that of a true electrical circuit, which is a network of connections between a number (many in electronic items) including sources of power (possibly batteries) which may be almost beyond comprehension in the CPU of your computer. How the electricity actually works is, in reality, unknown, the velocity of charge carriers matches nothing physical to the velocity of propagation and therefore must be faulty, despite hand waving of the "Group versus phase velocity" and other nonsense. The only information we have comes from equations and data that cannot be verified, the very low figure of a few m/sec or less come from a string of assumptions as long as your arm, and the relativistic velocity calculation is not supported by the accelerating potential, the answer is, therefore, we don't know how electricity works. Inside your computer chip signals travel and cause actions at about half the speed of light, that cannot be electrons (insufficient accelerating potential) therefore must be something else, or quite possibly our understanding of electrons is completely incorrect, which is quite possible. However, this is not the place to discuss this further although I would be happy to do so elsewhere.


    What I am saying is that your idea of an electrical circuit is excessively simplified for Engineering as a whole, if it helps you then fine, I don't mind, but please don't try to tell everyone else this is as far as it goes, it is not by a million miles, the reality is infinitely more complex. Consider this, your brain and nervous system appear to operate by electricity and therefore are electrical circuits. Is your brain part of a complex system or a group of individual circuits (by your definition) which presumably means that they can be isolated and adjusted. Do you think that is the view of a neurosurgeon? Everyone who has tried has found that such results in massive damage to function.
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