Nuisance Trip

[jamer8]

Hello to you all
I am a new member so please gentle with me.
My background includes an apprenticeship taken many years ago and following many opportunities I became a Service and Installation manager.
To save on wear and tear of this ageing frame I have decided to return to the tools (domestic only).
I have recently passed my 17th edition course and have the next two plus weeks booked on a training course reminding me of all the things I have forgotten and taking Part P.
I was asked to help a friend in need by fitting an extractor fan in his bathroom of a flat he is about to rent out. There was already a fan heater (fitted incorrectly) that he wanted removing so it seemed very straightforward.
On disconnecting the fan and trying to pull the cable back through a hole an RCCB tripped. This reset and I had no further issues. The RCCB is use to protect the whole installation it seems as the cu only has mcbs in the board.
I ran some additional cabling for the extractor and connected into the old heater circuit that looks as though it is a spur. There is also a DP cord switch and a separate RCD fused spur.
On energising the install the fan worked but after running for a while when I switched it off it tripped again but the mcb did not.
Is this simply a N and E fault on the original cable or am missing something?
Thanks in anticipation.
jamer8

 

[Engineer54]

Time to get your test equipment out me thinks....

 

[Silly Sausage]

I have recently passed my 17th edition course and have the next two plus weeks booked on a training course reminding me of all the things I have forgotten and taking Part P.

Here you go mate, Part P: Planning Portal - Approved Document P - Electrical safety - Dwellings

Save you a few quid. It's just part of the Building Regs, you don't need to go on a course!

 

[Octopus]

You need a MFT tester, an earth leakage clamp meter, a pencil, some paper and the knowledge of how to use them.

Simples.

 

[baldsparkies]

Get rid of the double pole pull switch and fit a single pole.
You will need a separate fan switch for local isolation though.
You will find that switching of a double pole switch under load often causes these kind of problems with rcd's ect.
As a quick check you can bypass the double pole neutral side by putting the two neutrals together
Then try switching the fan on and off and see if its cured the tripping issue.
If it works great, if not your back to what others have said.

 

[telectrix]

think baldsparkies hit nail on head here. a few millisecs deley between the L and N poles breaking could well trip and RCD.

 

[baldsparkies]

You also mention an rcd spur downstream of the rccb ??
What's the spec on that rccb ??
Pressing the test function on the spur and taking discrimination into account, you have to remember its a rented property.
Tenant walking down stairs, somebody presses an rcd spur that maybe shouldn't be there.
Lights out, tenant goes --- over ---.
Where there's blame there's a claim, and tenants love to claim.
Risk asses might seem ott but could be worth while.

 

[Engineer54]

Before making assumptions on what it may or may not be, get your test kit out and conduct the fundamental tests to prove (or otherwise) the installation and work you have undertaken is sound!!

 

[jamer8]

Thanks for all of your replies.
I only agreed to do this because it looked so simple!
The install has an RCD fused spur locally, then a DP cord switch, then the fan.
The local RCD is well out of harms reach but thanks for the heads up.
I will check out the DP switch and if required replace it, just didn't understand why it tripped before the new cable installation.

 

[UKMeterman]

Ok,
When pulling the cable out, it could have been a single (live only) pole switching RCD and you short N to E, this will divert current from N down E and cause an imbalance at the RCD ....

 

[Engineer54]

Thanks for all of your replies.
I only agreed to do this because it looked so simple!
The install has an RCD fused spur locally, then a DP cord switch, then the fan.
The local RCD is well out of harms reach but thanks for the heads up.
I will check out the DP switch and if required replace it, just didn't understand why it tripped before the new cable installation.

I take it you don't own/pocess any test equipment then??

 

[Farmelectrics]

take a test meter with you do your basic tests first

 

[Engineer54]

take a test meter with you do your basic tests first

You need to own/have the test equipment, to be able to conduct those basic tests!!

 

[Farmelectrics]

thought most sparks have there own mft tester e54 i most certanily have

 

[Engineer54]

Well not once has the OP mentioned any form of testing that he has conducted, so i can only assume he doesn't own the appropriate test equipment??

 

[Farmelectrics]

well my take is if your carrying out your own work or even doing a few cash jobs how do you no if the jobs safe if there not testing it

 

[Engineer54]

well my take is if your carrying out your own work or even doing a few cash jobs how do you no if the jobs safe if there not testing it

Exactly, .....You DON'T!!!!

 

[baldsparkies]

Thanks for all of your replies.
I only agreed to do this because it looked so simple!
The install has an RCD fused spur locally, then a DP cord switch, then the fan.
The local RCD is well out of harms reach but thanks for the heads up.
I will check out the DP switch and if required replace it, just didn't understand why it tripped before the new cable installation.

Your welcome,
Changing the dp switch to sp will almost certainly cure the problem.
Your profile shows as an installation manager with a number of years under your belt so take heed regarding the comments on verifying the circuit has been appropriately tested.
Its your responsibility as the last electrician working on the install, so you need to cover yourself and be confident in what your leaving behind.

 

[Geordie Spark]

Well not once has the OP mentioned any form of testing that he has conducted, so i can only assume he doesn't own the appropriate test equipment??

I could sell him my Metrel and replace it with a brick as it's only being used as a doorstop in the utility room now.

 

[VoltzElectrical]

I take it you don't own/pocess any test equipment then??

or possess?

:biggrin:

 

[VoltzElectrical]

well my take is if your carrying out your own work or even doing a few cash jobs how do you no if the jobs safe if there not testing it?

you're

know

they're


:ihih:...and the beat goes on

 

[Deleted member 9648]

Hello to you all
I am a new member so please gentle with me.
My background includes an apprenticeship taken many years ago and following many opportunities I became a Service and Installation manager.
To save on wear and tear of this ageing frame I have decided to return to the tools (domestic only).
I have recently passed my 17th edition course and have the next two plus weeks booked on a training course reminding me of all the things I have forgotten and taking Part P.
I was asked to help a friend in need by fitting an extractor fan in his bathroom of a flat he is about to rent out. There was already a fan heater (fitted incorrectly) that he wanted removing so it seemed very straightforward.
On disconnecting the fan and trying to pull the cable back through a hole an RCCB tripped. This reset and I had no further issues. The RCCB is use to protect the whole installation it seems as the cu only has mcbs in the board.
I ran some additional cabling for the extractor and connected into the old heater circuit that looks as though it is a spur. There is also a DP cord switch and a separate RCD fused spur.
On energising the install the fan worked but after running for a while when I switched it off it tripped again but the mcb did not.
Is this simply a N and E fault on the original cable or am missing something?
Thanks in anticipation.
jamer8

I know it's already been said in post #3....but please,please dont be conned into a 'part p course'. Part P is not a qualification.Read the document Archie has posted and you've done 'the course'. Dont feed the leeches any more than you have to.

 

[jamer8]

Thank you all for your interest
Sorry for the delay in responding, been to a funeral!
I have been given some great pointers thanks.
My transition back to the tools began a while ago and I am sure you know the more you manage the wider the divide.
This work was only done to help out and not to be clever.
I am genuinely off to sunny South Wales for the next two weeks plus for my courses and testing etc is covered fully.
Many thanks again

 

[Geordie Spark]

or possess?

:biggrin:

That was the Chinese spelling ...... old E54 forgets where he is sometimes.

 

[Octopus]

Thank you all for your interest
Sorry for the delay in responding, been to a funeral!
I have been given some great pointers thanks.
My transition back to the tools began a while ago and I am sure you know the more you manage the wider the divide.
This work was only done to help out and not to be clever.
I am genuinely off to sunny South Wales for the next two weeks plus for my courses and testing etc is covered fully.
Many thanks again

So you don't own a tester then.....