What should trip RCD or MCB

[Sparks74]

Hi

Guys i am wondering whether you could clear something up for me,in the event of a line neutral short circuit on a lawn mower cable should the rcd or mcb for that circuit trip?
Basically got a dead short on a very poor attempt on repair on a severed lawnmower cable,the mcb tripped at the DB but rcd didn't & also the plug top fuse didn't blow either.checked the test button on the rcd & that is funtioning fine also put martindale on socket & that was also fine.

Is this normal or do i need to do any further investigation?

any advise would be greatly appriciated

Cheers

J

 

[sparks_114]

That is correct. RCD doesn't usually deal with overload or short circuit whereas an MCB does. RCD is only concerned with out of balance current, ie what comes out in the line conductor must come back in the neutral. Hope this helps

 

[mike2790]

Firstly, i wouldnt attempt to repair a flex, your best off re-flexing the lawn mower with an entire new length of cable. An MCB tends to be more sensitive than a standard plug top fuse and its a good thing that it has tripped. Rcd's work on earth leakage, so unless current has leaked to earth it wont trip. Everything sounds normal to me apart from the repair job

 

[Deleted member 26818]

If you intend repairing the cable, purchase a cable connectorrather than some chocolates and some tape.
Make sure that it's the right way round, exposed pins on the machine side of the cable.

 

[Sparks74]

Yeah the repair job was rather lame,been meaning to do it for ages but......anyway was gonna to do a through crimp on the line & neutral,do you guys think that'll be sufficent?
My main concern was that the rcd didn't trip but as you guys all seem to be saying as it was a line neutral dead short then it shouldn't have i feel at ease...well sort of anyway!lol

 

[mike2790]

Yeah the repair job was rather lame,been meaning to do it for ages but......anyway was gonna to do a through crimp on the line & neutral,do you guys think that'll be sufficent?
My main concern was that the rcd didn't trip but as you guys all seem to be saying as it was a line neutral dead short then it shouldn't have i feel at ease...well sort of anyway!lol

personally i wouldnt say it would be sufficient. the best way to assess whether or not it will be sufficient is to think of PAT testing, for example, after the repair would you be able to stick a nice green sticker on it or a dirty red one? i know your not PAT testing it but if you use that way of thinking it will give you an idea of what is acceptable and whats not. like i say, you should re-flex it or go with spinlondon's idea.

 

[telectrix]

hang on . is it 2 core cable? if so, as said previous, RCD will not see a fault unless leakage to earth. if you must crimp connect, stagger the joins and use heatr shrink, bu best to re-cable. or buy a petrol mower

 

[VoltzElectrical]

Yeah the repair job was rather lame,been meaning to do it for ages but......anyway was gonna to do a through crimp on the line & neutral,do you guys think that'll be sufficent?
My main concern was that the rcd didn't trip but as you guys all seem to be saying as it was a line neutral dead short then it shouldn't have i feel at ease...well sort of anyway!lol

no. as spin london has said, you need to make off the good bits of the flex into suitable connectors. YOU MUST NOT THROUGH CRIMP! Don't skimp, do it properly. and SAFELY!