T.p.n isolators for extract fan

[just add water sparks]

Briefly went to help a guy /Sparks first fix a job(i was agency) and he seemed to have an idea of wiring an additional spur in conjunction with a triple pole isolator for a bathroom fan.I have normally never used a spur and just used a triple pole isolator which in turn was fed from a 6amp m.c.b via various connection points.When i queried this the sparks ( young and green) he remarked that one of his supervisors said that the fans should be fused at 3amp/5amp as manufacturers warranty would be not be valid if a fault happened.I said i could see his point ,but thought it was a bit overkill and have never done this on other jobs. About 40 other jobs i have seen must been wrong then lol!!!! anyway agency workers are low lifes i think in his mind and not allowed opinions.lol

 

[just add water sparks]

understand completely Guitarist, i am refering to post no.9 .When using a 1361 fuse in a FCU to protect the fan.As post no.9 refers to a 60898 mcb tripping sooner ???????? would have thought 3amp 1361 should have blown first but not sure where i can confirm this,telectrix prob. right ??? confused

 

[MarkieSparkie]

interesting post telectrix , so it begs to answer the previous posts of someone being prosecuted that did not put in a 3amp fuse.Fan caused a fire as it was not fused at 3amp!!! as you say discrimination (or new 17th term selectivity i think!)wise the 60898 would trip first,so a 3amp would have made no difference?.Just for legal clarity could you give me the page no./ time characteristics on bs 7671 for the 60898 and also for the 1362 fuse if thats what i believe the crux of the issue is about.Thanks

BS EN 60898 BGB Page 301
BS 1362 not in BGB see link Note. curves shown are 1A and 13A, you will need to interpolate for 3A - http://www.farnell.com/datasheets/10867.pdf

 

[Guitarist]

From what I can gather in this situation..

6A MCB will trip within 0.1 secs at 30A
3A BS1362 fuse will blow at a max of 8x its rated current in 0.1 secs (24A)........ 3A fuse safer

6A MCB will trip within 100 secs at 14A
3A BS1362 fuse will blow at 6.3A max.................3A fuse safer


I would conclude that across the board, the 3A fuse is indeed the better OCPD in this instance.

Please feel free to correct me in this. I am very interested to see if I have interpreted the graphs incorrectly.

 

[Des 56]

Anyone ever have a fuse or a mcb actually disconnect a domestic fan ?

My own feeling is neither will go,the fan windings will cough up the proverbial before either of them get their act together

With my reasoning in mind,the cheap and nasty fans will no doubt be safer than the quality jobs,so good protection can be achieved by purchasing down market gear :biggrin5:

 

[Strima]

On a well maintained fan I can't see too many problems when the fan packs up, the problem occurs when there's 30 years of crap in there that tends to catch fire. Seen countless fans that look like the vacuum cleaners been emptied into them, such a delight to clean.