Discuss Full spread of tests after CU change. in the Electrical Forum area at ElectriciansForums.net

Status
Not open for further replies.

Guitarist

Regular EF Member
Messages
5,250
Location
Norfolk
I know that many electricians only carry out quick and basic tests after a CU change, but I thought I'd share this with you.
I am a fussy so and so, as many of you already know, so following a CU change I carry out every test imaginable. Having established no shared neutral, good bonding, good IR checks, etc. prior to carrying out said change, I got stuck in to a full spread of testing after installing it....
Was in the process of carrying out an R1+R2 test on every point in the lighting circuit, when I came across an open circuit at a bedroom ceiling rose... Checked switch, connections etc, but no joy. After half an hour in the loft, found the supply to the bedroom lighting joined in a JB but with the cpc ends not connected, just sitting there happily a few inches apart outside the JB, covered in loft insulation.
This is why I would rather be a few quid out of pocket time-wise, than skimp on testing.
 
O

Octopus

Its a bit like not bothering to check the ring circuit at every socket - I always do but suspect many don't
 
OP
Guitarist

Guitarist

Regular EF Member
Messages
5,250
Location
Norfolk
Its a bit like not bothering to check the ring circuit at every socket - I always do but suspect many don't
Exactly mate. I was only saying to my wife this morning that I'd no doubt spend many boring hours on a hot sunny day, carrying out all these tests just for it all to be perfect, and then this pops up!
Makes it all worth while :)
 
S

steveberry11

I know that many electricians only carry out quick and basic tests after a CU change, but I thought I'd share this with you.
I am a fussy so and so, as many of you already know, so following a CU change I carry out every test imaginable. Having established no shared neutral, good bonding, good IR checks, etc. prior to carrying out said change, I got stuck in to a full spread of testing after installing it....
Was in the process of carrying out an R1+R2 test on every point in the lighting circuit, when I came across an open circuit at a bedroom ceiling rose... Checked switch, connections etc, but no joy. After half an hour in the loft, found the supply to the bedroom lighting joined in a JB but with the cpc ends not connected, just sitting there happily a few inches apart outside the JB, covered in loft insulation.
This is why I would rather be a few quid out of pocket time-wise, than skimp on testing.

Good for you Guitarist. This is what testing is for. There seems far too many people looking for reasons not to fully test.
 

trev

Regular EF Member
One lad I worked with refused to do it claiming he wasn't trained to as he didn't have 2391. I always thought a spark should be able to test his own work, some others refused to test a new install because "You know it's going to be ok" disgusting attitude
 
S

steveberry11

One lad I worked with refused to do it claiming he wasn't trained to as he didn't have 2391. I always thought a spark should be able to test his own work, some others refused to test a new install because "You know it's going to be ok" disgusting attitude

Quite right Trev all electricians should have a good understand of inspection and testing regardless of being 2391 trained.
How can electrician carry out electrical work walk away and let the tester carry the can if he misses a fault.
At least they have to sign the EIC cert for construction.
 

ExArmy

Electrician's Arms
Messages
715
Location
cumbria
question, do you do the RCD test on every circuit? or do you just do it on one circuit on each rcd (for a 17th board) and duplicate the results?
 
O

Octopus

One lad I worked with refused to do it claiming he wasn't trained to as he didn't have 2391. I always thought a spark should be able to test his own work, some others refused to test a new install because "You know it's going to be ok" disgusting attitude
I think its the "I can't be bothered attitude" - no pride in the work they do, god help them if they ever go down the self employed route in he future...
 

trev

Regular EF Member
One guy sat in his car one day making up test results and then photocopied the sheets and submitted them for every rewire he did on the decent homes programme. The same guy now has AC status with NICEIC and has guys working for him.
 
G

Guest55

question, do you do the RCD test on every circuit? or do you just do it on one circuit on each rcd (for a 17th board) and duplicate the results?
2 rcds in a CU = 2 rcd tests
preferably at the device itself or from a nearby socket if easier.
 

DNS1

Electrician's Arms
Messages
1,054
2 rcds in a CU = 2 rcd tests
preferably at the device itself or from a nearby socket if easier.
I was taught to always install a socket right next to the CU, partly for this purpose. Not essential obviously but surprisingly handy.
 

ExArmy

Electrician's Arms
Messages
715
Location
cumbria
2 rcds in a CU = 2 rcd tests
preferably at the device itself or from a nearby socket if easier.
exactly. today another spark tried to tell me it had to be done on every circuit! i normally do it on each ring main(providing theres one on each side), at the socket with the highest ZS normally i figure if it works there it'll work eveythere else.
he said it was being thorough, i said it was wasting time! didn't go down well...
 
OP
Guitarist

Guitarist

Regular EF Member
Messages
5,250
Location
Norfolk
question, do you do the RCD test on every circuit? or do you just do it on one circuit on each rcd (for a 17th board) and duplicate the results?
As long is nothing is plugged in to a socket then there can be no leakage and the test will be accurate.
The CU I just fitted has 7 RCBO's, so 7 lots of tests at the board. Before I finish a job for good I like to do a ramp test on each RCD somewhere in the circuit, just for that last minute "nice" factor. :)
 
G

Guest55

exactly. today another spark tried to tell me it had to be done on every circuit! i normally do it on each ring main(providing theres one on each side), at the socket with the highest ZS normally i figure if it works there it'll work eveythere else.
he said it was being thorough, i said it was wasting time! didn't go down well...
Well at least you know where to come for the real low-down on testing theory ;-D
And your collegue doesnt know his arse from his elbow.
 
D

dim_bulb

Why not 3probe test the rcd at c.u you can reset rcd and look at resultsAltought many instruments have auto recd
 
D

Dave 85

One lad I worked with refused to do it claiming he wasn't trained to as he didn't have 2391. I always thought a spark should be able to test his own work, some others refused to test a new install because "You know it's going to be ok" disgusting attitude
I certainly don't test a new install the way I was taught at college. The main difference being the only RFC testing I do is end to end continuity of the 3 conductors at the C/U. If anyone would like to slag me off for this I would appreciate if you could accompany said slagging off with an example of how doing it this way could create a dangerous situation.

I will also happily admit that I get my R1+R2 readings after a C/U change by calculating Zs-Ze or R1+R2/4 in the case of an RFC. If they ask for an EICR I will give them one. If they want a C/U change with a cert, that is what they get.
 
G

Guest55

As long is nothing is plugged in to a socket then there can be no leakage and the test will be accurate.
The CU I just fitted has 7 RCBO's, so 7 lots of tests at the board. Before I finish a job for good I like to do a ramp test on each RCD somewhere in the circuit, just for that last minute "nice" factor. :)
I wouldnt be ramp testing new devices to be honest.
 
OP
Guitarist

Guitarist

Regular EF Member
Messages
5,250
Location
Norfolk
I certainly don't test a new install the way I was taught at college. The main difference being the only RFC testing I do is end to end continuity of the 3 conductors at the C/U. If anyone would like to slag me off for this I would appreciate if you could accompany said slagging off with an example of how doing it this way could create a dangerous situation.

I will also happily admit that I get my R1+R2 readings after a C/U change by calculating Zs-Ze or R1+R2/4 in the case of an RFC. If they ask for an EICR I will give them one. If they want a C/U change with a cert, that is what they get.
So you only do the tests which you deem necessary Dave?
 
D

Dave 85

I always IR everything trev. Polarity with a voltage tester on the tails
 
G

Guest55

"The main difference being the only RFC testing I do is end to end continuity of the 3 conductors at the C/U"
Not a slagging but how do you prove polarity and IR
Your earth loop tester will go a long way in proving polarity at each socket although admittedly not infallable.
IR test can be a one hit global test before removing the old CU.
Like Dave says , if they want a detailed inspection they can pay for an EICR.
 

ExArmy

Electrician's Arms
Messages
715
Location
cumbria
I certainly don't test a new install the way I was taught at college. The main difference being the only RFC testing I do is end to end continuity of the 3 conductors at the C/U. If anyone would like to slag me off for this I would appreciate if you could accompany said slagging off with an example of how doing it this way could create a dangerous situation.

I will also happily admit that I get my R1+R2 readings after a C/U change by calculating Zs-Ze or R1+R2/4 in the case of an RFC. If they ask for an EICR I will give them one. If they want a C/U change with a cert, that is what they get.
thats fair enough for a new install. but when you have to do periodics on houses and you don't know how it's wired, you might want to do the rest of the tests just so you know whats what. recently i found what appeared to be a ring was just a load of radials spurred from the 1 and only point on the ring which was 6 feet from the DB, found by cross connecting L-CPC and testing each socket.
and about the R1+R2 reading for the cert, I always add r1 and r2 and divide by 4 and just write that down. thats what i was taught at college
 
G

Guest55

Just realised Dave is talking CU change I'm talking new install.
I'll stfu now:)
The whole forum is talking CU change , hence the topic title in bold letters above your post.
Glad you could join us Trev lol.
 
OP
Guitarist

Guitarist

Regular EF Member
Messages
5,250
Location
Norfolk
My point really, in posting this thread, was simply to emphasise that although it's tempting to cut corners at times, there are times (especially on an old install) when doing all the tests not only gives you peace of mind, but can actually find a fault you really weren't expecting to find.
 
OP
Guitarist

Guitarist

Regular EF Member
Messages
5,250
Location
Norfolk
The thing with being ultra thorough is that you always discover something you'd rather wish you hadnt lol.
I know what you mean mate. Ignorance is bliss sometimes. Glad I found this one though, and the customer was happy paying me to sort it.
 

VoltzElectrical

Regular EF Member
Messages
2,231
I certainly don't test a new install the way I was taught at college. The main difference being the only RFC testing I do is end to end continuity of the 3 conductors at the C/U. If anyone would like to slag me off for this I would appreciate if you could accompany said slagging off with an example of how doing it this way could create a dangerous situation.

I will also happily admit that I get my R1+R2 readings after a C/U change by calculating Zs-Ze or R1+R2/4 in the case of an RFC. If they ask for an EICR I will give them one. If they want a C/U change with a cert, that is what they get.

ok, i will. I recently was doing a PIR on an installation and was doing Ze at sockets. Couldn't get a reading at one half of a double socket outlet. No earth. Go figure. If I had only tested at one point in the ring then nobody would have ever realised the danger of no earth present at an outlet. Big lesson learned.
 
Status
Not open for further replies.

Permanent unswitched live colour?

  • Brown

    Votes: 100 72.5%
  • Black

    Votes: 38 27.5%

Electrician Talk

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
Top