I hate RCDs

[milkman]

Is it common for RCDs to just die completely? I was learning to put up with the fact that they trip because; er, oh its Monday, or because a squirrel looked at it in a funny way* and now this has died outright.
Is this the future? crappy RCDs that won't let you do any work in between walking back and forth to reset them or now having to toss them and spend time taking them apart?
Rant over.
Rant-backs welcomed or even words of calm and wisdom if you have any.


*I can believe these as more valid reasons than anything the world of physics has to offer

 

[cambournepete]

What was wrong with the good old-fashioned fuse that you could replace with a dirty great nail eh?

 

[Ateallthepies]

I don't come across many RCD's that simply don't work. I do find some that don't trip within the specified limits and some that trip too soon as per their spec for which you need an RCD tester with ramp function.

Never felt inclined to take one apart either :shock:

Installed and working correctly they are great bit's of kit but when they play up they are a royal pain in the harris especially when retro-fitted to an installation that has some previously unknown faults :wink:

Steve.

 

[RogerS]

There have been several instances of bogus RCD's for sale on eBay.

 

[Eric The Viking]

I wouldn't dismantle them. there are mechanical adjustments in some designs (screws held with thread-lock) that set the trip current.

It's far more likely that either there is a genuine circuit fault (or a big phase shift, when a motor or sommat starts up), or the wrong type of RCD has been fitted. You *might* need the 100mA type to cope with 'leaky' or very inductive equipment (for example, switch-mode power supplies usually cause a dribble of current on the earth connection).

I had a 110V transformer trip an RCD last week. They only had about ten feet of cable between them, and the transformer wasn't under load at the time. I'm 98% sure the transformer is fine - I think it was just it being an inductive load (and I'd removed its earthing for testing purposes, effectively increasing the inductance, I think)

Get a sparks in to check it all thoroughly.

 

[Jimidalliance]

Check the type of RCD it is, if it's a B type it's rated for domestic use and therefore will be more sensitive to leaks and imbalances, that's what causes it to trip when you plug in a trafo!
For a workshop you really need a C Type which is designed for an inductive load, ie fluorescent lighting, motors etc, or D Type which is designed for circuits where you have high inrush currents on start up.

I was a sparks in a former life!!!!
Hope this helps

 

[Eric The Viking]

Oh yes, it is most definitely a type B. This transformer was being used on-site (upstairs in my bathroom re-fit!).

Got a 'proper job' for the workshop...

 

[NetBlindPaul]

Jimidalliance,
I think you have misread the OP, or there is some other confusion here.
RCD's are not rated in types B, C & D.
These letters are used to signify the current sensitivity to typically inrush currents on BSEN60898 and later type BS3871 miniature circuit breakers.
RCD's have no load current sensitivity at all unless they are an RCBO to BS EN 61009.
With regard to RCD's you will have ac sensitive, dc sensitive, and time delayed types of both.



It is not permissible to simply swap a 30mA RCD for a 100mA because of nuisance tripping, as you would be changing the fundamental additional protection of the installation and could leave the user open to electrocution.

They do fail, however the predominant failure mode is that of not tripping due to mechanical jams within the trip mechanism.
If you are seeing random disconnections then perhaps you need to get the install checked out.
An earth leakage clamp meter, insulation resistance test and an rcd ramp test and a trip time test should be enough to give an indication of what is causing the problem, though without seeing the install it is difficult to tell.

 

[Jimidalliance]

Right you are!! I was getting my rcd's and mcbs mixed up!!!

Sorry about the confusion