/Lounge Blogs/Current Flow/Q7. E or G - Bolted or Clip-in? What is this type of fuse and where can I find this out in the Regs?
27, Mar, 2020

Q7. E or G - Bolted or Clip-in? What is this type of fuse and where can I find this out in the Regs? Dave Austin and Gary Gundry investigate a b**tard of a question!

Bolted or Clipped fuses, Type E or G or something else? If you get a question like this in your exam or even in day to day work, it's a question that you can only answer if you either just know it or can find it in the Regs - but it's not as easy as it should be!

Video transcript:

Here we go again then with another exam question.  A BS 88-2 fuse can be either bolted or clip-in.  Which system type covers bolted fuses?  And, we've got four options of few system types.


So, on the surface, this looks relatively simple.  But, what we can say is, if you don't know anything you're going to struggle with this one.  You are, indeed, Dave.  If you take a look at the index, for instance, which is one of our ‘go to’ places and take a look under fuses and look down the list; although there's a few sort of teasing bits that look they might take you in the right places there's no mention of bolted or clipped in fuses in the index.  So, as a start point, it's a waste of time that.  Yes, you could get embroiled in the index and waste valuable time.


So, this is a question then you really need to know where it is, and we're going to show you right now.  I think most will know that a BS 88-2 fuse is a HBC, a high rating/breaking capacity for, sort of, industrial type applications.  You say that ‘industrial’.  Anybody that’s worked in industrial will know that instinctively but domestic; probably not because they’re probably going to familiar with circuit-breakers and that. So, there's another place in 7671 that covers fuses and I'm going to take you to two places that do that.  But I'd like to just take a quick step back really just to refresh ourselves with ‘what are these devices’? Now we've got 4 answers, and I'm going to tell you and show you there's only two of those so two are red herrings.  So, it would be a complete guess if you didn't know where it is.


So, this is bolted, and so that’s where the bolts go, and this is clip in.  So, if you're familiar with those and you've used them on various applications you will know where they are, and they are E and G. But, you're still no further because I'm not being very helpful. But, we’re 50% down the road.  If we know this, we just know this, because we learned it, at least we know now there’s half those answers. Now, I'm going to show you right now where E and G is mentioned in 7671; sneakily very well hidden.  And, what we're going to do is ... chuckle ... it is, it’s tucked away somewhere really well.  So, what you need to do is go to Table 41.2, which covers fuses, cartridge fuses, rewireable fuses ... and we're looking for general purpose motor 88; doesn't have to be motor circuits, because it could be anything else 88-2.  Fuse system E, is bolted, and G is clip-in.


Excellent. Okay, now it's going to be one of those questions you think ‘I've seen it’, ‘I'm going to remember this’, ‘this is really helpful’, alright, but I'm not going to remember that.  It also appears in Appendix 3 that covers all the time current characteristics of various devices.  So, you’ve got the cartridge fuses, you got your semi-enclosed, which is your rewireables, and obviously your BS 88-2 - so fuse system E, bolted again.  So, that's quite handy one, and clip-in there.  It would so convenient if they had called them B and C.


So, given that it is an open book exam and all the answers are here finding the answer knowing a few of the key tables can often get you get you there.  So, let's just go back and look at the question  ...


Surprise visit from Karen – bringing drinks! 


So, the answer is Fuse system E.


So, we've sort of helped a bit.  But it does prove this is one you need to know.  You would need to know one of these. Umm, an admission here, Dave!  I wouldn't be able to tell you ‘off the top of my head’ which one it is, right, I know it’s a bit of a shocker for you because I do know an awful lot about this stuff in the regs, but I would know where look - just to be absolutely certain.


Well, okay coming at it from my point of view, which is usually a bit more simplistic than yours, I do notice that bolted has got an ‘e’ in it.


I think that's a really useful tip, right. You’ll never forget now, will you?  Nope, little things like that can always. The day Dave taught Gary something! 


We hope you found that useful, and I should stress that the questions we’re addressing in this series aren't official exam questions taken from any paper - but they’re very typical of the sort of thing that you will find on questions from any of the examining bodies for the 18th edition.  If there's a question or a subject that you'd like us to address in these sessions then please do drop me a line at Dave.Austin@learninglounge.com.


For more questions, visit our website www.learninglounge.com/18  – and there’s even more questions when you subscribe to one of our courses!


Other exam questions are available in this series and they’re free to view at www.learninglounge.com/social/blog




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