cable cut should rcd trip?

[kernow]

Hedge trimmer cable cut clean through :innocent . TNCS - RCD protected circuit 32Amp - should the rcd not have tripped as there would have been an inbalance? Nothing tripped - no fuse blew.

 

[Andy™]

most hedge trimmers are class 2, so the blade will not be earthed. in which case, cutting though would be dead short L-N, so fuse should have blew. no fault to earth so no imbalance to trip RCD. unless someone was to touch it, or possibly if the now exposed live came into contact with ground

 

[kme]

Though the short should have blown something - maybe the fuse in the plug?

 

[Manator]

I agree with Andy, most would be class II and have no earth cable present. As for the short L to N, we would have to consider the speed and how clean the cut was, if the cut was made at such a speed that contact between L and N was made and cleared before the trip time of the breaker/fuse, I would say this is unusual, but however remote possible. I think this event would be cause for a near miss, and be reported as such to the H&S for evaluation, and testing. You are trained, and as such are fully aware of the dangers, but if this was to happen to anyone who has no idea, a very nasty accident could happen.

Incidents like this can only be safeguarded against if the HSE are aware, you do not get into trouble by reporting such events, in fact they very often send a letter of thanks for highlighting such dangers.

 

[Badger]

thats why i dislike new mowers, and hedge trimmer cables being 2 core, thats y i cut each of our garden equipment cables from machine and made one long cable with a plug and socket type connector that fits all the machines, this cable has 3 cores, l n and earth which in simple terms how ever long it takes to cut cable it WILL EARTH in that cable and trip our rcd, job done

 

[Manator]

It still needs to go to evaluation, an interesting fault, that very well be overlooked.

 

[NozSpark]

I've seen this myself before,,,

But never thought to report it to HSE:coat

 

[Badger]

what sparked me (pardon the pun) to get amn earthed cable for all outdoor garden equipment was the fact many years ago i cut thru our hedge trimmer cable by accident :Blushing and it only blew the plug fuse, bearing in mind that fuse was only 10 amps not 13, but it didnt trip our rcd or even the mcb, (fault not high enough) that was on a cable with only l and n and i was shocked (no pun intended ) that the rcd never even saw the fault so thats why i changed our cable to a earthed 3 core, its the same for all the chrimbo lighting in the garden i earth any and all the cables from the set of lights connection as close to the tree, bushes etc as i can to an earthed cable/supply, i might be over doing things but i have a healthy respect for safety and electricity in general

 

[steptoe]

well, I tend to disagree with why it should trip, or even blow the MCB/fuse,

but I'll bet the may well be a slight nick in the blade,

if the trimmer is indeed DI as most are and it cut the neutral first then there will not be an over load,

at the speed of reciprocation it more than likely would blow the flex back slightly before it would blow the (probably 13A) 1361 fuse.

 

[Evans Electric]

I must say that I have known flexes be cut without fuses blowing (specially rewirable)