I made the calculations and have some questions. the sheets you sent helped me a lot in understanding the calculations. RE: Underground cables in Concrete Encased PVC ducts Adam1980 (Electrical) If the 3 cables in one duct of the upper row –first or last will be loaded with 175 A the ampacity of the rest of cables will drop to 161.5 A. The first way result was 166 A and the second-considering also equally loaded cables-163.5 A. There are slight differences between results. This way is difficult to transfer in Excel. This is not a relation but a procedure in order to find the final temperature distribution and iterate the way until reach the maximum permissible. If we intend to load differently one or more cables then we have to follow ch.2.2.3.1 Unequally loaded cables. This way uses global formulae simplifying the calculation. We calculated the ampacity for 27 single core cables equally loaded following IEC 6 ch.2.2.7.3 External thermal resistance of the duct (or pipe) T4”’ connected with 2.2.3.2 Equally loaded identical cables. RE: Underground cables in Concrete Encased PVC ducts 7anoter4 (Electrical) 26 Oct 13 09:21 in PVC duct) to see what is the ampacity and compare with the one given by the manufacturer for laid direclty in ground.įinally, you said that you are using information from ABB for the 9 cables arrangement but is it valid to use the factors from IEC 502 when considering 3 x 3 configurations, the factors are for horizontal arrangement only! correct? I am doing calcualtions only for one cable (3x1 300 mm.sq. I believe i have all data i need to calculate the ampacity using the equations in 287-1-1 and 287-2-1 but i am not getting a logical result. for a rough estimation is this valid?įor the duct in question it is a 3 x 3 configuration vertically and horizontally there is 50 mm spacing between the ducts (165 mm center to center)and 75 mm from the concrete encasing border to the duct order also vertically and horizontally. Posts that fail to meet above requirements will be removed.So if the rating for cable in ducts is 166 A and for directly buried is 184 A the factor in between is around 0,9 (assuming all other conditions are the same). r/AskElectricians /r/askanelectrician /r/diy /r/homeowners /r/electrical. Suggesting the burning scrap wire to remove the insulation will result in a ban. NO DIY, SELF-HELP POSTS, OR QUESTIONS FROM NON PROFESSIONALS. Incorrect, unsafe, or hazardous information will result in a ban. This includes company names of contractors. Back it up with a code reference.ĭO NOT post any personal information. Rules Generalĭon't be a dick, and adhere to the reddiquette If you are looking for DIY or general help please visit /r/askelectricians Pre-Apprentices start here before posting Help your fellow Redditors crack the electrical code. Talk shop, show off pictures of your work, and ask code related questions. Reddit's International Electrical Worker CommunityĪka The Great Reddit Council of Electricians In this photo, have a piece of paper with your username and date written on it. To get verified, send a photo to the mods that has your certificate/seal/card. Users with have verified their qualifications with the Mods Then message the mods with the country you are from. To add your country's flag to your flair, you must select a title from the drop down menu.
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