RCD tripping dilemma

[Des 56]

That well known saying is often used in the electrical industry,

"Its better to be sorry than safe"
or is it
"The Show must go on"




Regardless of safety

 

[2BobSparky]

I'm sure AC units (air con???) like fridges/freezers can trip RCDs, there aren't a few of these units and rfc's and lighting all on one RCD is there?

Yep, that's how it is.

 

[Darkwood]

Looks like it's going to be out of hours testing then. The RCD tripping shows there's a fault somewhere which needs identifying and rectifying, I personally would not have left the circuit without RCD protection as the designer deemed it necessary to have it.

Even a quick test taking 15 minutes could highlight problems and reduce the amount of downtime the office has. Protection is there for a reason.

A tripping RCD does not always mean there is a fault present, alot of modern office equipement have electronics that have a designed leakage current to earth hence the term High Earth Currents which must be accounted for in design when you have a no' of computers or light fittings with electronic ballasts, in the OP case i would first do a earth current test to establish if there is already a high leakage which may be related to designed leakage as opposed to fault leakage.

 

[Strima]

Very true mate, trying to read a post and reply with two screaming kids and a nagging wife running around doesn't help...

 

[vernam616]

Why not call an electrician?

 

[2BobSparky]

Looks like it's going to be out of hours testing then. The RCD tripping shows there's a fault somewhere which needs identifying and rectifying, I personally would not have left the circuit without RCD protection as the designer deemed it necessary to have it.

Even a quick test taking 15 minutes could highlight problems and reduce the amount of downtime the office has. Protection is there for a reason.

What about lights being included as apart of the RCD protected circuits? Isn't this cause for concern? Why did the designer include lighting?

Are lights only likely to cause RCD tripping when a lamp blows or can their componetry do it too?

 

[Darkwood]

Very true mate, trying to read a post and reply with two screaming kids and a nagging wife running around doesn't help...

No worries lol.

Think the OP needs to refresh himself to the workings of an RCD as well as well as what i would class a designed earth leakage before addressing this problem further, it may be the case that it is a faulty item creating the nuisance tripping but going into this with half the knowledge could lead to many hours of frustration and no conclusion.

 

[2BobSparky]

Why not call an electrician?

An electrician is the one who moved the MCB feeding the AC units away from being RCD protected in an effort to see if the MCB will still trip.

 

[Plonker 3]

I think maybe you are out of your depth with this, and walk away now or get someone with more experience to help you.

I will refer you to my earlier answer.

 

[tony mc]

Are you doing the work or just making enquirys 2Bobsparky ?

 

[2BobSparky]

I think maybe you are out of your depth with this, and walk away now or get someone with more experience to help you.

If you don't want to help, which is why I am here, then perhaps you should walk away right out of this thread.

- - - Updated - - -

Are you doing the work or just making enquirys 2Bobsparky ?

I'm making enquiries so I can better understand the situation.

 

[Darkwood]

What about lights being included as apart of the RCD protected circuits? Isn't this cause for concern? Why did the designer include lighting?

Are lights only likely to cause RCD tripping when a lamp blows or can their componetry do it too?

As ive already mentioned i suggest you read up on the working of an RCD and what situations would cause them to trip, rcd's under the 17th it is usual to have an rcd covering all circuits in some form or other, there are exceptions but you should already be knowledgable in this area if you are doing this kind of fault finding, no offense meant here when i say you seem to be lacking knowledge in some basic areas that i would expect an electrician to have, we will try help where the situation has caused you confusion but with re' to replies to this thread you seem to lack knowledge of how rcd's function, designed high current earths, reg's re' rcd protection and when its needed as well as when it can be left out.
Its the fact your struggling with knowledge in several areas which you should already know, if you inform us better on your background we can answer your queries better, but all the help your getting your are answering with another question.
So what is your background, are you apprentice, qualified, etc etc then from there we can head you in the best direction.

EDIT....
Sorry you answered my question before i saw it as i was writing this post.... If you have had an Electrician out already i would of expected the questions you are asking here should have been explained by the electrician, i personally wouldn't leave a customer with a rcd tripping without fully informing him of the possible causes and the steps been taken to eliminate it, that aside this particular issue can get quite indepth and random guesses from other members may just add to the confusion and although you slated another member for suggesting you leave it to a proffesional; i must agree with them and the only hope is the electrician you have is competent in his job.

 

[2BobSparky]

As ive already mentioned i suggest you read up on the working of an RCD and what situations would cause them to trip, rcd's under the 17th it is usual to have an rcd covering all circuits in some form or other, there are exceptions but you should already be knowledgable in this area if you are doing this kind of fault finding, no offense meant here when i say you seem to be lacking knowledge in some basic areas that i would expect an electrician to have, we will try help where the situation has caused you confusion but with re' to replies to this thread you seem to lack knowledge of how rcd's function, designed high current earths, reg's re' rcd protection and when its needed as well as when it can be left out.
Its the fact your struggling with knowledge in several areas which you should already know, if you inform us better on your background we can answer your queries better, but all the help your getting your are answering with another question.
So what is your background, are you apprentice, qualified, etc etc then from there we can head you in the best direction.

I will indeed, but for the time being I was just looking for opinions on what would be the best plan of attack.

I am qualified, but working in the maintenance game, knowledge and skill set is comprimised by any given day's jobs, which can involve heating/cooling/plumbing etc and sometimes very little hands on electrical work. I would rather come in here and ask a load of questions and look like an idiot and be mugged off then do it in the workplace, put it that way!

There is a very knowledgeable and expereinced bloke on site who I often refer to, but in this case he has in fact domne something that to me didn't seem quite the right thing to do and to others on here is downright not acceptable ie. removing MCB from RCD protection to stand alone and see if fault occurs again.

So in closing, after reveiwing the replies in here these are the options:

-ramp test RCD
-divide sub circuits across two or more RCDs
-swap MCBs for RCBOs, thus eliminating need for RCD protecting several MCBs
-insulation resistance test

 

[Darkwood]

Circuits dont need to be RCD protected in all cases, which comes more into play in commercial and industrial senerio's, it relates to there been an instructed person present, although i dont exactly know the circuit design and layout of said building there is nothing wrong with dropping off the A/C from the rcd as a temp' measure or the fact 'depending on circuit design' whether it needs to be covered in the first place. I see now your situe' regarding you limited experience due to your job but would strongly suggest as i have always done that you regulary top you knowledge up on the regs and also visit this site often which will help with the areas you lack in. If you havent already i would suggest you get a copy of the reg's and on-site guide as they apply to commercial and industrial just as much as they do domestic, you obviously have a guy you respect regarding his knowledge but rather than sit back for the next 10yrs catch up to his level and revel in the security that you can walk into any similar job if not take over from him with confidence, ive seen so many resident in-house electricians over the yrs who are just not up to their job because they have slipped so far behind, and must say in these times alot are losing them and its expected to get worse rather than better.
Take it as constructive advice as it not a dig in any form.

 

[Darkwood]

Regarding the other collegue it maybe questionable on his order of approach to this problem but he is classed as you are as instructed ppl and taking it off the rcd is allowed and anyone on site that would need informing of the situe should be, if the cause is proving to difficult to find it is quite acceptable to remove the rcd for fault finding purposes and fitting and putting each circuit through a rcd one at a time, although not a method i would employ as there are many ways to skin a cat but just explaining it can be acceptable to do so as long as any one that needs to is informed of the situe.