A Son's Love
Clean Jokes
An old man lived alone in Ireland. He wanted to dig his potato garden, but it was very hard work.His only son, who would have helped him, was in prison for bank robbery. The old man wrote a letter to his son and mentioned his predicament.Shortly, he received this reply,"For HEAVEN'S SAKE Dad, don't dig up that garden, that's where I buried the Money!"At 4 A.M. the next morning, a dozen policemen showed up and dug up the entire garden, without finding any money.Confused, the old man wrote another note to his son telling him what happened, and asking him what to do next.His son's reply was: "Now plant your potatoes, Dad. It's the best I could do from here."
Popularity: 1%
Posted in Life.
By Ver
– January 27, 2012
I was able to get hold of the latest editons of the Philippine Electrical Code. To further provide service, a wiki has been created to have the latest Philippine Electrical Code annotated.
Please visit us at Philippine Electrical Code Annotated.
Popularity: 4%
Posted in Design, PEC, Standards.
Tagged with Standards.
By Ver
– June 21, 2011
Note: A conductor size expressed in mm² shall be IEC standard and sizes in AWG or kcmil shall be IEEE standard.
I. Introduction
Conductors may be either solid or stranded. Solid conductors may be used for sizes up to 12 AWG [1] or 16 mm² [2]. Solid copper conductors having nominal cross-sectional areas of 25 mm² and above are for particular types of cable, e.g. mineral insulated, and not for general purposes [2]. Solid conductors larger than these would be stiff and difficult to install, therefore stranded construction is normally used for these larger conductors.
II. Conductor stranding (IEEE 525)
The number of strands and size of each strand for a given size is dependent on the use of the conductor. Common stranding classes are summarized in IEEE 525 [1] Table C.1. The number of strands per conductor is standardized and is summarized in IEEE 525 [1] Table C.2. Class B stranding is normally used for substation installations.
IEEE 525 Table C.1 - Conductor stranding
| Class |
Use |
| B |
Power cables |
| C |
Power cables, where more flexible stranding than Class B is desired |
| D |
Power cables where extra flexible stranding is desired |
| G |
All cables for portable use |
| H |
All cables where extreme flexibility is required, such as for use on take-up reels, etc. |
| I |
Apparatus cables and motor leads |
| K |
Cords and cables composed of 30 AWG copper wires. |
| M |
Cords and cables composed of 34 AWG copper wires. |
IEEE 525 Table C.2—Stranding construction
| Class |
14-2 AWG |
1-4/0 AWG |
250–500 MCM |
| B |
7 |
19 |
37 |
| C |
19 |
37 |
61 |
| D |
37 |
61 |
91 |
| G |
49 |
133 |
259 |
| H |
133 |
259 |
427 |
III. Conductor stranding (IEC 60288)
IEC conductors have been divided into four classes, 1, 2, 5 and 6. Those in classes 1 and 2 are intended for use in cables for fixed installations. Classes 5 and 6 are intended for use in flexible cables and cords but may also be used for fixed installations.
IEC 60288 Conductor classes
| Class |
Description |
| 1 |
solid conductors |
| 2 |
stranded conductors |
| 5 |
flexible conductors |
| 6 |
flexible conductors which are more flexible than class 5 |
References:
[1] IEEE Std 525™-2007 IEEE Guide for the Design and Installation of Cable Systems in Substations
[2] IEC 60228:2004 Conductors of insulated cables
Popularity: 1%
Posted in Design, IEC, IEEE, Standards.
Tagged with conductors, Design, Standards.
By Ver
– January 19, 2012
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