neutralwiring
A normal plug point has the wiring structure of the normal cct diagram I've drawn below. I'm thinking about plugging a device into the outlet in a permanent way and keep the switch closed and control it using a switch at a separate place. My problem is will there be any electrical sparks or anything if I connect the live and neutral to the supply line at once?
According to 2011 National Electrical Code article 300.3(B), No. For verbiage, see this answer. For one explanation why, see this answer.
Another reason not to do it, is because you could end up overloading the grounded (neutral) conductor. Depending on if the two circuits are on the same branch circuit, different branch circuits on the same leg, or different branch circuits on different legs, you'll run into different situations. However, in two out of three of these situations, it is very easy to overload the grounded (neutral) conductor.
Let's examine what happens in a 120/240V single split-phase system, in a few different configurations. The circuit breakers in these examples is a combination circuit breaker, with 15 ampere thermal overcurrent protection and magnetic short-circuit protection.
With a single branch circuit supplying a 15 ampere load, we see that there will be 15 amperes on the grounded (neutral) conductor. This is fine, since the grounded (neutral), and ungrounded (hot) conductors are both sized to carry 15 amperes.
In this situation, we'll see 30 amperes on the grounded (neutral). However, since we're also drawing 30 amperes through a single breaker with 15 ampere overcurrent protection, the breaker will open.
This is the dangerous situation, since the breakers will not trip. Each circuit will draw 15 amperes on the ungrounded (hot) conductor, but the grounded (neutral) conductor will see 30 amperes. Since the conductor is only rated for 15 amperes, the conductor is in danger of overheating and starting a fire.
If the two loads are on different legs. You'll find that while each ungrounded (hot) conductor sees 15 amperes, the grounded (neutral) carries 0 amperes.
what I have done was directly connect the 3, to A (needless to say colours matched with colours). then use another 3 additional short strings of wires (from the connectors A which accepts the inputs) to connect A and B.
it's been weeks and both working fine.
Best Answer
Your circuit diagram looks perfectly safe.
A two pole isolator is often used where the need is to make a circuit safe to work on, not simply to turn off the power.
Earth should not be switched, your diagram looks correct.
Disclaimers As always, check the law and codes in your country. You might need to have a professional certify it safe. There will be rules about the type of wire, termination, labelling etc. The body of the 2-pole switch should also be earthed, and the earth cable should run in the conduit between them, not taking a short cut. The power should run through the switch, not there-and-back. You are probably not allowed to fasten the cord of a portable device to the wall in any way, or run it under a carpet or floor. You're probably not allowed to mount a hand tool in a permanent way. I can't tell you that your system is safe, but the electrical concept is not dangerous.