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| Thread ID: 67539 | 2006-03-30 21:22:00 | Quick question re power leads | Miami Steve (2128) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 442174 | 2006-03-31 03:05:00 | The "heavy duty" label on Wharehouse et al cables is not a good indication. Often its just 1.0 mm csa cable, or if you are really lucky 1.5 mm csa. A "real" heavy duty cable would be at least 2.5 mm csaThe warehouse.... The warehouse where everyone gets something cheap and disposable? I'm used to working with cables that take 2 people to roll them up, and 2 people to carry them. However they are to run somewhat more than a couple of power tools sharing a 10A socket. Anything that can be thrown over shoulder as easily as a warehouse cable is NOT heavy. Heavy duty often just means it has more than a token amount of insulation, or in the case of warehouse products, may mean simply that it's red and costs more. |
personthingy (1670) | ||
| 442175 | 2006-03-31 06:25:00 | If you want a graphic illustration of what personthingy refers to, dissect a set of "200 amp" or "400 amp" car battery jumper leads that you get from the Warehouse and similar places. Big fat leads with tiny amounts of copper (about 1.5 mm copper conductors). The 200 or 400 amp would equate to their melting point current. |
godfather (25) | ||
| 442176 | 2006-03-31 06:49:00 | Another thing to remember is that your cable must be fully uncoiled in order to deliver a full 10A of current. If it is coiled up it will only be rated to about 5A max. | Johnnz (7246) | ||
| 442177 | 2006-03-31 07:05:00 | Another thing to remember is that your cable must be fully uncoiled in order to deliver a full 10A of current. If it is coiled up it will only be rated to about 5A max.Sorry..... that's wrong. Coiled or uncoiled the delivery is the same, it just that if coiled and overloaded there is a far higher chance of melting the cables insulation in the process. Melting insulation = Bad |
personthingy (1670) | ||
| 442178 | 2006-03-31 08:46:00 | The "heavy duty" label on Wharehouse et al cables is not a good indication . Often its just 1 . 0 mm csa cable, or if you are really lucky 1 . 5 mm csa . A "real" heavy duty cable would be at least 2 . 5 mm csa Understood, although we are still talking about something plugged into a 10 amp socket after all . I haven't been near the Warehouse to check its offerings but an ETL? or ESL? brand labelled for Household or light duty was 1 . 0mm . I will report back on whether the cables labelled heavy duty have more copper . |
PaulD (232) | ||
| 442179 | 2006-03-31 08:48:00 | Sorry..... that's wrong. Coiled or uncoiled the delivery is the same, it just that if coiled and overloaded there is a far higher chance of melting the cables insulation in the process. Melting insulation = Bad I may be wrong but a coiled cable will also generate a magnetic field which could cause problems. |
mikebartnz (21) | ||
| 442180 | 2006-03-31 08:56:00 | Understood, although we are still talking about something plugged into a 10 amp socket after all. True, but it's what you can get out the other end that counts. If at 30 amps its going to drop to 200 volts, its not suited as an example. A standard induction motor of 1.5 HP will draw ~ 5 amps running, but ~ 35 amps momentarily when starting (and that is an unloaded motor). Add to that the compressor load and its likely to top ~ 50 amps (momentarily). But the "momentary" load will be a lot more than "momentary" if the voltage sags significantly at the end of the extension cable, as the motor cannot then start. A stalled induction motor will draw "lots of amps" and blow the fuse/trip the breaker very quickly. None of this then has any relationship to the "10 amp" socket it is plugged into, which is actually designed for such momentary starting loads, as are the fuses/breakers. But the system is not designed to have a "series resistor" (the small conductor/long/ extension flex) in the circuit. |
godfather (25) | ||
| 442181 | 2006-03-31 09:06:00 | I may be wrong but a coiled cable will also generate a magnetic field which could cause problems. As the phase and neutral are actually a "twisted pair" in the cable layup, it will mostly be cancelled out. A small inductance may result but not of any significant value. But heat is very noticeable. In a 30m flex coiled up on a drum I once measured a temperature rise of 1° per minute with 5 amps flowing, as a test. |
godfather (25) | ||
| 442182 | 2006-03-31 09:17:00 | As the phase and neutral are actually a "twisted pair" in the cable layup, it will mostly be cancelled out. A small inductance may result but not of any significant value. But heat is very noticeable. In a 30m flex coiled up on a drum I once measured a temperature rise of 1° per minute with 5 amps flowing, as a test. I hired an electric waterblaster once and they provided the 10metre cable and they said any longer and it would damage the motor. |
mikebartnz (21) | ||
| 442183 | 2006-03-31 09:33:00 | I hired an electric waterblaster once and they provided the 10metre cable and they said any longer and it would damage the motor . Either it was an extremely thin cable, a very powerful water blaster, or most likely scenario, the hire firm exaggerated knowing full well people would mistreat the gear a little bit . Either way, this is a cable resistance / power loss issue, not an overheating of cable issue . |
personthingy (1670) | ||
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