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I think it's a basic question for people who know circuits.

I am trying to extend a cable of circuit board however I am not sure which wire to join with other wire.

The orange cable (with blue, white and brown wires) is the original cable which was connected to the circuit board and white cable (with black, red and green wires) is the cable I want to connect to extend the original cable.

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Here is the circuit diagram of board if it helps.

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UPDATED: Here is the image of board before disconnecting original orange wire.

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  • \$\begingroup\$ The circuit does not match either cable colour set, so how can you say the orange cable is original? And, if the orange cable was original, which terminals was the orange cable connected to? You did keep that info before disconnecting ?? \$\endgroup\$ – Solar Mike Aug 12 '17 at 9:57
  • \$\begingroup\$ Also, the wiring diagram shows a four-core cable connection to the motor. Both your cables are three core and not suitable. \$\endgroup\$ – Transistor Aug 12 '17 at 10:24
  • \$\begingroup\$ @SolarMike The blue wire is the wire coming out from the motor and connected to the circuit board. yes i took a picture of circuit board before disconnecting. (see updated question above) \$\endgroup\$ – YOU Aug 12 '17 at 10:34
  • \$\begingroup\$ @Transistor There are only 3 wires coming out of orange wire and connected to board. See updated question above. \$\endgroup\$ – YOU Aug 12 '17 at 10:35
  • \$\begingroup\$ My crystal ball is in the repair shop \$\endgroup\$ – Chu Aug 12 '17 at 11:08
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From an electrical point of view what matters is adequate copper to carry the current and adequate insulation to prevent short-circuits and electric shock. From that point of view any adequately rated cable could be used provided that they are connected through correctly.

The problem is that insulation colours generally have an implied meaning. e.g. Brown = live, blue = neutral and green/yellow for earth. If you were to extend the pump motor wiring with your white cable you or someone else may, in the future, assume that the green/yellow is an earth whereas it is live. This is a good enough reason not to use it.

I recommend you find a three-core + earth cable. Connect the earth to the motor chassis and the earth terminal in the controller. The other three should maintain the correct relationship to the original wiring.

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Figure 1. Capacitor start induction motor wiring. Source: DIY.SE.

The diagram of Figure 1 may help you understand what you are actually wiring. The motor has two windings - one powered from L and N and the other wired L - capacitor - N. The diagram also shows how to change the direction of rotation - which you don't want! The diagram does not include the earth connection which you should include.

If you're going to do some non-standard wiring then label both ends clearly and permanently.

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DIY cable labels. Source: How to make DIY bread-clips to organise your cables and power cords.

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  • \$\begingroup\$ Thank you for your detailed answer. It is a submersible motor under 200FT in the ground and i think the people who setup it placed the ground wire down there. I just want to extend the wire of board so i can place the box in basement. The white wire i am using is far thicker than original orange wire. Can i still use white wire if i could not find same orange wire? \$\endgroup\$ – YOU Aug 12 '17 at 11:16
  • \$\begingroup\$ Heavier wire is fine. Label everything up at both ends. See the update. \$\endgroup\$ – Transistor Aug 12 '17 at 11:29
  • \$\begingroup\$ Will use. What are the symptoms if it is not good? Wire will get hot? \$\endgroup\$ – YOU Aug 12 '17 at 12:17
  • \$\begingroup\$ You're kind of changing the question as we go here and that's not fair to your readers. At 200 ft voltage drop becomes an issue. We haven't got a motor current, cable cross-sectional area (\$ mm^2 \$ or AWG), etc., so we can't give a better answer. \$\endgroup\$ – Transistor Aug 12 '17 at 12:22
  • \$\begingroup\$ I am not replacing orange wire which means the wire down 200FT will be same. i am just adding a heavier wire to orange wire so i can place box anywhere i want. Is this dangerous? \$\endgroup\$ – YOU Aug 12 '17 at 12:27
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IMO do NOT use that white cable to extend the orange one - as the white conductor is not earth (possibly signal or phase) and the white cable has green - which on those very old cables was earth or ground.

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  • \$\begingroup\$ So what should i do? Maybe the brown and green are earth wires? \$\endgroup\$ – YOU Aug 12 '17 at 10:40
  • \$\begingroup\$ The white cable had red as live, black as neutral and green as earth. The newer cables brown is live, blue is neutral and green/yellow is earth. Either your country has a different code for the colours or the orange cable has a specific purpose and the wires are colour coded for that. I suggest you source the correct cable. \$\endgroup\$ – Solar Mike Aug 12 '17 at 10:44
  • \$\begingroup\$ Finding wire with same colors is quite hard. All 3 wires aren't same? \$\endgroup\$ – YOU Aug 12 '17 at 11:04

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