What is the Minimum Internal Bending Radius for Cable Used in Fixed Wiring According to BS7671
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- čas přidán 26. 06. 2024
- How to workout the minimum internal bending radius of fixed wiring like PVC/PVC twin and CPC (twin and earth) SWA and MI cables (MICC or Pyro) with full demonstration using BS 7671.
Using the diameter of the cable and then correct factor from BS7671 On-Site Guide Appendix D table D5 we can workout the minimum bending radius of cable’s.
BS 7671 minimum internal radii of bend in cable for fixed wiring includes full demonstration of calculations and bends
== 🕐 Time Stamps - Cut to the action 🕕 ==
00:00 - Minimum bending radius of cables
00:46 - On Site Guide Appendix D table D5
01:41 - Diameter of the cables
02:47 - Diameter of twin and CPC cables (twin and earth cables)
03:38 - Measuring the widest part of the cable
04:50 - Calculation for twin and CPC cable (2.5mm2)
05:30 - Draw a circle
06:09 - Smooth bend
07:17 - 6 mm2 twin and CPC cable next
07:34 - Diameter of the cable
08:26 - Calculation
09:00 - Draw a circle
09:20 - Smooth bend in 6 mm2 twin and CPC cable
10:24 - Steel wire armour SWA cable
10:56 - Diameter of SWA cable
12:22 - Smooth bend in SWA cable
12:54 - Diameter of mineral insulated cable (MICC or Pyro cable)
14:22 - Smooth bend in MI cable
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Hi brilliant video currently doing my 2356-02 and not been shown this thanks keep the good videos coming 👍😀
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@Kyng Ronin Yea, I've been watching on instaflixxer for months myself :D
@Kyng Ronin yup, I have been using InstaFlixxer for since november myself :D
@Kyng Ronin yea, have been watching on InstaFlixxer for months myself :)
Thanks for advice on what to annotate in the onsite guide 👍
Just in a middle of my 7671 training and this video is absolutely brilliant ❤️
Thanks guys 🤜🤛
Beautifully Explained 🙏
Perfect, perfect video. Well done really. Thanks a lot.
Oh happy memories of my 4years at Watford college.
But much easier to use a 4 way JB as they are about 30mm . For the 6mm2 TW&E a ceiling rose cover is about 60mm I am of course talking about the real world no one has the time to faff about with a ruler and a compass , this is more to do with wiring diagrams and drawings, but available skills to have. And should be learnt .
Brilliant video I love watching these it refreshes my brain
Fantastic As always Gaz
Clearest explanation of a skill not known by many electricians.
Biggest facts I’ve ever heard
Excellent clear and to the point video, thanks
Massive thanks 👍🏻
Cheers Gaz. Great Vid, Onsite guide updated :-)
Sorted 🦾
Great content as always
Thanks Gaz
great video
Perfect clarification to me from you thanks a lot for clearing💥💥💥 my doubts
😀👍🏻
Nice Explanations. very useful and thank u for sharing your knowledge
👍
Hi. Can I have soft copy of Electrical Standards Books.
good video
Hi. Thanks for watching GSH Electrical 👍
Great video. So is there anything with regards the bending of the individual cores of twin and earth, eg behind a socket or switch? Thanks
Nice1. So, considering TWE for example, when the oversheath is cut back and conductors are dressed for termination, can we just bend and loop them around a tiny radius as much as we like? I hope so! (Within reason of course:)
Nice video, very clearly presented.
I'm a bit surprised the OSG is saying minimum 6x diameter for all sizes of SWA. If you look at most manufacturers data it says 8 x for sizes greater than a certain conductor size, say 16sq.mm. If you are working out large SWA's going around cable tray for example, a factor of 8 x would be my advice when designing cable tray size.
Hi. Thanks for the quality comment the question in the exam my learners sit needs them to state a factor of 6 for SWA. I would always recommend manufactures date is used on the design of an installation thanks for watching GSH Electrical 👍
Thanks for another great video Gaz. Bad news...I've just been fettling some 50 year old 2L2.5 MICC. I probably bent the cable a little more than I should have (although not more than the radii mentioned in your video) when I was doing the fettling, but now I've pulled the cable straightish again, I seem to have a short across the live, neutral and earth on the cable in question. Is this a common problem and is there anything that I can do to try to rescue the cable?
Is there any difference in the beginning radius of t&e if it's being bent on the minor axis instead of the major?
Sir please a example for higher dia multiple cable.
Do these bending radii apply to bends due to internal or external bends round corners, such as the corner of a room or exiting a hole in a rafter? As the bend is on the narrowest diameter does this also effect the radii factor?
Good stuff...I wonder how many 25mm meter tails are over bent?...probably every single one.
Out of curiosity....when you have bent the radius....how much straight cable must there be before the next bend. Example...Meter tails entering a CU from the bottom...which have to be installed into the top of the main switch...which usually ends up a "U" turn...downwards...that's 2 x radii (30 to 40mm) in a very tight (not enough) space in a CU.
Hi. If the bending radii conforms you can make as many bends as you like... hands up I am guilty of one or two tight bends in meter tails over the years. Thanks for watching GSH Electrical
Hi, very clear.
I wonder if there is any difference if I bend it on its flat area (instead of bending side area of the cable as you shown on the video)? Thanks.
Hi, rule of thumb smooth bend 👍. Thanks for commenting and watching. Gaz
That doesn't seem to answer the question, unless you are saying: No difference, just use the same smooth radius if you bend it the other way, which would seem logical. Although I can see bending the other way, it's much more likely you would get a sharp bend rather than a smooth radius.
I can see how this rule applies on cable runs, but what about in confined spaces such as inside a socket, where it's obviously difficult to achieve and cables often get bent double?
Can you or anyone explain how much resistance increases with the bends ? I assume that is the primary reason for these min radius rules. I ran a 10 ga extension cable from my garage into my basement to get a 20 A circuit without those infernal GFI's. My evehicle pulls 12 amps continuously and I noticed the gentle bend where the cable came down from the outlet I was suprised to find it a little hot at the bend. So now I limit the amps to 11. Why would electricity care about these bends? Can other things significantly increase resistance ? - tension, a clamp?
Aside from 522.8.3, is there in 7671 that stipulates bending radii?. GN1 Selection & Erection page 80 is the nearest thing I can find?
PNX Electrical page 144 in the On-Site Guide
@@GSHElectrical aha, but nothing in the big blue? I get most of the OSG is just duplication from BBB, so surprised I can't find it in big blue.
Hii, Can you use that to bend around more than the 90 degrees?? I'm interested to know as its for automotive application
Hi. Yes you can. Thanks for commenting and watching GSH Electrical
GSH Electrical ah thanks for replying 😊 that's going to help me out a lot.
"MI worked once." Is that on one bend in the entire length or the that particular bend you are working on?
Hi. The bend you’re working on 👍. Thanks Gaz
what is bend reduis of 300mm
Am I looking at this wrong, all these formula's bring them to 90 degree bends?
0:09 did my guy just rap....
🤔🤫😂
I dont think there is a single house basher in the Uk that even considers this . Rewires would be next to impossible
lol' 'housebasher' 😆 Deffo one of these wired my brand new 'Persimmon' house. Shite quality. Had to install new CU myself and remake loads of terminations. Rubbish....
How many times on sites do you see sparkys drawing circles lol
Never but you should pick it up on an EICR through knowledge. These videos are for learners training in the electrical industry. Massive thanks for commenting and watching. Gaz 🦾
True enough mate. I always watch your videos, helps keep stuff fresh in the mind. Hard to remember everything from years ago.
Sent a few quid to your daughters fund other week. Hope it helps
Thanks for posting the videos, enjoy watching them
Some of 'em are probably better at drawing circles than installing cables....
sorry but if I was to do that for every house re-wire, each indevidual cable run would take me about 30 to 35 minutes maybe more.
Who would actually use this formula/ If it was a designer, would the installer really spend time makeing sure the radius was correct?
Dont think so!!!!.
not so much relevant on site but good practice to learn this in any case. Surface mounted/clipped direct cables look awful without the correct radius. Also, whats the rush?