Test Meter - Forum Sponsors since 2007!
This official sponsor may provide discounts for members
Advertisement - Content continues below
Advertisement - Content continues below

Discuss Trip switch tripping inexplicably... in the Commercial Electrical Advice area at ElectriciansForums.net

C

ChrisR

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Working on some home electrics with a peculiar problem which I hope someone might be able to comment upon…

Randomly, the trip switch trips…! It’s an old trip switch and fuse box and I’ve been lead to believe that the old style trip switches will eventually trip and not be able to be reset BUT in this case it is simply trips frequently (often overnight but not exclusively so. No apparent pattern, ie. not at the same time or after the same appliance is switched on) so what I’m wondering is whether when they get old these trip switches are also prone to randomly tripping? Don’t want to install a new trip unless it is likely that this is the source of the malfunction because the new unit will have a lower resistance and therefore if this isn’t the source of the problem will potentially trip more frequently.

For reference, I have taken a couple of pictures of the fuse box and trip switch for illustration:
Fuse box = http://www.flickr.com/photos/[email protected]/2161458715/
Trip switch = http://www.flickr.com/photos/[email protected]/2162255542/in/photostream/

Hope someone can suggest something...

Thanks,
Chris
 
Advertisement - Content continues below
C

Cirrus

  • Thread Starter Thread Starter
  • #2
Taking a guess I would say it needs replacing as it may just be too sensitive now as it is an old unit.
 
C

ChrisR

  • Thread Starter Thread Starter
  • #3
Are modern trip switches less less sensitive/more intelligent and therefore less prone to this kind of problem?

Thanks for your help.
 
C

Cirrus

  • Thread Starter Thread Starter
  • #4
I don't think it is that so much as they do age - even 'newer' style mcb's need replacing from time to time because of inexplicable tripping.
 
C

ChrisR

  • Thread Starter Thread Starter
  • #5
but it is realistic that the trip switch is the cause of the problem...?

Thanks,
 
T

TonyM58

  • Thread Starter Thread Starter
  • #6
looks like an old ELCB (earth leakage circuit breaker). I used to work on VOELCB's (voltage operated) they were dreadful. Cant quite see what the IDeltaN trip current is on your trip. i have seen them as high as 500mA on old ones.

Have you considered that there might actually be a problem on your circuits? Have you tested it at all?

What supply system have you got? is it TT, TNCS to TNS? Is the ELCB protecting the whole board? If so, and its a TT you would need to replace it with a 100mA RCD and then put a 30mA on the required circuits (supply to shed, sockets likely to feed equipment outdoors etc)

Be usefull to have a bit more info!

regards

Tony
 
C

ChrisR

  • Thread Starter Thread Starter
  • #7
Info on the breaker is as follows:

Chilton
Type 'E' current operated earth leakage circuit breaker
Rated tripping current 500mA, 240v, 60A, 50~
 
T

TonyM58

  • Thread Starter Thread Starter
  • #8
So it is an ELCB! and a 500mA! (damn i'm showing my age now!).

i would certainly look to changing this, but be prepared that the ELCB MAY be doing its job (ie detecting a fault). Trying to get the old grey matter working ( and i aint got time to look it up) but i'm pretty sure ELCB's worked on a slightly different principle to RCD's


Would need to know the supply to go any further though.

Chris, no disrespect, but have you sufficient electrical knowledge to be able to answer the questions? (like what the supply is?)

If not I would be happy to help you out on this forum in sorting this out

regards

Tony
 
C

ChrisR

  • Thread Starter Thread Starter
  • #9
Hi Tony,

No offence taken but you're quite right in guessing that I'm not very clued up about the subject.

How do I work out the information you need about the supply?

Thanks for your help,
Chris
 
C

Cirrus

  • Thread Starter Thread Starter
  • #10
Tony's your man - lecturer trhrough and through. I could explain but it would take me about 20,000 words when I think Tony will reply in a succinct way!
 
M

Minky

  • Thread Starter Thread Starter
  • #11
Never heard that one about circuit breakers tripping without an explanation.The only apparent reason that such a device would operate would be if it were to be close to its permitted rated value.Have seen this when additional load added to circuits,namely lights when new fittings or extra ones are added.Misuse when resetting the device is also detrimental to the internal workings of the mechanism as a significant amount of heat is transferred across the terminals when excess current is applied even for a fraction of a second.
Be sure before resetting or replacing any overcurrent or RCD devices that all circuits are safe to be energized.
By the description of the earlier post and by the authors own admission i would advise that only competent persons undertake installation work to this degree.
 
T

TonyM58

  • Thread Starter Thread Starter
  • #12
Minky, its an ELCB, ie an earth leakage device, its not got overcurrent protection. So its if its tripping its likely to be an earth leakage problem not an overload situation.

Ok, to work out the supply:

Do you have an earth electrode / earth spike outside? If so its a TT system. Look at your consumer unit and try to follow where the main earth cable goes.

If it goes to the metallic outer sheath of the incoming supply the its a TNS. If its joined to the incoming neutral (normally via abox with PME written on it) then its TNCS.

Once we know what the supply is we can work out what we need to replace the ELCB with.

To be honest because you've got old 3036 fuses i would look at a complete consumer unit change, and listen to Minky's wise words, this is not for the DIYer!!

Ok, had a quick look at ELCB's, and yes i was correct in thinking they worked differently to RCd's. The ELCB actually monitors the earth line, and if senses any current in it, it assumes this current must have leaked from the live conductors.

They were prone to indiscriminate tripping from voltages appearing on any part of the earthing or bonding system.

Oh, and i should add if you do change the consumer unit this is a notifiable work under Part P - just gets better dont it!
 
Last edited by a moderator:
C

ChrisR

  • Thread Starter Thread Starter
  • #13
I know I have an earth spike outside so it must be a TT. Earth cable appears to be well attached to it...

Moving home this year so whilst wanting to get the problem sorted I don't want to get more work done than necessary!

Thanks guys,
 
T

TonyM58

  • Thread Starter Thread Starter
  • #14
Thought it would be a TT, ELCB's were commonly used on TT systems.

Bottom line is you have two options:-

ignore the problem, although this may give you problems when trying to sell the house

Resolve the problem, which will invlove replacing the existing ELCB and BS3036 fuse board with a new split load board, with a 100mA RCD at the front end and a 30mA RCD protecting outside supplies (if any) and sockets likely to feed equipment outdoors.

As i have said, this is notifiable work under Part P, so you will either have to use a sparks registered with a competent persons scheme or pre-notify the work to the council amd do it yourself or use a non ccompetent person scheme sparks. The sparks should give you a Periodic Inspection Report (PIR) with schedules of inspections and test results attatched. Of course, the idea of doing it and NOT telling your local building control is an absolute no-no. i definetly wouldnt do that. Ok it will save you a lot of money, but Part P of the building regulations SAYS you have to tell them. So you have to. Dont you.

As i have brought up previously as well, be prepared that if the ELCB is detecting a genuine fault, (and its a 500mA trip) then you will be replacing it with either a 100mA or 30mA trip (depending on which circuit the possible fault is on)

the 17th edition is kicking in now, and under that its likely that all of your circuits will be on 30mA RCD's or RCBO's. Either way its a consumer unit change.

You can pick them up for 30 quid, but really, its not a job for the untrained guy, plus you have to be able test the circuits, so you you have to have a test meter as well!

Sorry it aint better news, but the ELCB aint gonna get 'better' overnight!!
 
Last edited by a moderator:
C

ChrisR

  • Thread Starter Thread Starter
  • #15
Thanks for the comprehensive response Tony.

Whilst it does sound hopeful that it's just the ELCB which may need replacing I'm wondering what the process is to test all the circuits to actually pinpoint where/what the problem is before spending on work which may not be necessary. I had a guy round who wasn't cheap but didn't seem able to give me any informaiton regarding the cause of the problem... Thoughts?

Thanks
 
Advertisement - Content continues below

Reply to Trip switch tripping inexplicably... in the Commercial Electrical Advice area at ElectriciansForums.net

Electrical2Go - Online Electrical Supplier
This official sponsor may provide discounts for members
Advertisement - Content continues below
Top Bottom