**CU Changes And YOU**

[nickblake]

Actually a 250 volt is a legitimate test especially when doing PIR's i will never carry out a PIR and do an straight IR test at 500 volts and i was taught many years ago not to , the reason is simple if for any reason there is still an appliance plugged in boiler washing machine PIR's even a sub board with an RCD main switch the chances of blowing these up are very high and could be very costly , so an initial test of 250 volts followed by a test at 500 volts if the installation is clear and mark it down on the Certs even omitting the LN test by shorting out theL and N and testing that between earth and noting this down on the certs it is a acceptable way of testing , totally agree with malcome comments

 

[mike2790]

Actually a 250 volt is a legitimate test especially when doing PIR's i will never carry out a PIR and do an straight IR test at 500 volts and i was taught many years ago not to , the reason is simple if for any reason there is still an appliance plugged in boiler washing machine PIR's even a sub board with an RCD main switch the chances of blowing these up are very high and could be very costly

actually, did you not even read my post? i never said just test at 500v and fingers crossed nothing blows up, quite the opposite. this threads turned a little bit ----for-tat and a bit boring too. however i feel that testing each circuit fully is the best way to go. just a quick question to you and malcolm, do you do a full test cert for a board change? and if so what do you record as r1 or r1+r2? because in a lot of instances you would need to disconnect loads at the furthest point of each circuit to obtain a reading, for example a shower circuit. the only reason i ask this is that if your disconnecting the loads, why not test at 500v anyway? also the term 'competant person' is the reason a lot of us 'time served' electricians are struggling to find work, but thats for another thread i suppose.

 

[malcolmsanford]

I assume Mike your meaning R1 + R2 as your talking about a shower circuit and not a ring final circuit. Yes when I do an EIC fora new installation or an addition, I do the R1 +R2 on it, as I think it is a better than the R2 only test, which I'm quite entitled to do on an EIC, and on a CU change I might just do that on a lighting circuit if there are outside lights on PIR that I don't want to start taking apart. On a PIR I have often just done an R2 only espicially on hi bay warehouse lighting. Again as the tester I deem what tests are necessary.

I really don't know where this is going, In fact after this post I do think you need some refreshing on testing. It's R1 + R2 on a shower or any other circuit,you only do r1 rn and r2 on a ring final circuit. Also you just not only do a r1 test,there is no such recognised test, I think your meanig R2 but then I'm not sure what you mean.

I'm disputing you term legitimate. Now we can bat this about as much as you wish, IMO you using the term not legitmate when referring to a 250V test is not true, it is a perfectly Legitimate test.

It is completely irrelevant if you consider it legitimate or not, that is quite rightly your opinion on it. But you can not advise others that it is not a legitmate test when in the guide we adhere to advises it is.

A lot of us time served electricians do a 250 volt LIVES/EARTH test before we even start on a CU change, it is often used as a guide, and I would be quite within my rights to do that only test and put it on the EIC if I wanted to, as it is not a departure from the regulations. I'm sure like me the majority of us do also do a 500 volt test after, if we feel it warrents it and it is not likely to damage anything. After all I'm not going to go around an entire installation disconnecting everthing, possibly taking out 30 or 40 down light lamps, disconnecting transformers, PIR or dimmers, unless I found a problem.

 

[mike2790]

I really don't know where this is going, In fact after this post I do think you need some refreshing on testing.

why would i need refreshing? and who are you to say so? my qualifications are as good as any. we're merely trading opinions. people like you who get so ---- about things are the reason a lot of people avoid posting on sites such as this. this image springs to mind.

 

[nickblake]

Sorry mate didnt mean to offend and yes i did read your post i just wanted to express my opinion and belive you me i do a full circuit test drives my apprentice nuts and i will re do a test to i will never cut corners , my real point was that in some circumstances you could miss an item boiler etc with one of those nasty hidden away sockets behind cupboards etc with the years of doing inspections i have see almost every thing , when i test an R1R2 of say a lighting circuit i test at every point till i get the highest reading at the end of the circuit and the reason for this is beacause i got caught out a few years ago when i did a test R1 R2 insulation and Zs all tested fine but what i hadnt spotted was that the polarity changed half way down the circuit and then changed back again so you wouldnt spot it so im a swine when i test now , as for the competant and time served sparks struggling for work , i sympathise with those who are struggling ,but when you have the 3 week wonders and the 10 minuit PIR guys doing 6 PIR 's in a day this is where they need to stop it

again please accept my appologies if i offended you ,as i do take our trade very seriousley

Nick

 

[mike2790]

but when you have the 3 week wonders and the 10 minuit PIR guys doing 6 PIR 's in a day this is where they need to stop it

or the one hour board change brigade!

cheers nick

 

[Spudnik]

Change the record fellas,

I didnt start this for it to become another qualification vs experience bashing thread.

 

[nickblake]

Sorry jason wasnt my intention ,ive change the record and im listening to when im cleaning windows

 

[Lioned]

Hi. when doing a CU change is it an absolute requirement to upgrade the tails to 25mm.Got a job where the meters outside and tails 16mm go up cavity in a conduit,not enough room to get 2 x 25mm up there.
Can upgrade earth to 16mm but no way get new tails up.Its a 60 amp cut out so ok for 16mm,but if i use this one for my assessment is it going to be ok if i reconnect with the existing 16mm tails ?
Thanks.

 

[malcolmsanford]

The OSG does advise the tails being 25mm now, (see pg 17 section 2.2.3) but ultimately it is the DNO that will decide what tail sizes they want as it is their fuse that is supplying fault protection.

As the Fuse is 60 amp then keeping the 16mm tails will be ok, what it will mean though is that the DNO would not upgrade to a 80amp most likely and definately not a 100amp.

As it is an assement just advise the assessor that the protection device is 60amps and as the customer did not want to the extra cost and disruption that would have been caused by trying to fit 25mm ones, and that should be that. Remember your being assesssed to be a cash cow, he will not fail you if you explain the logic behind doing something.

 

[oldtimer]

Just to sober everyone up here in Glasgow today a Sherif found a "handyman" at fault for the death of a 21 month old toddler after the child put a "disconnected" oven supply cable in his mouth so heres the deal as far as I am concerned this forum is not a pi&&ing contest its for electricians to help each other out and yes there is some old heads like me are big on safety so when advice is given the person asking it needs to realise the they are tapping into a wealth of knowledge yes I know that sometimes advice can sound condisending but remember this is not a game people can and do die with house electrics and over the years every apprentice I have had I have said "do you trust me when I tell you its isolated ?" and when I get the "O yes" reply I tell them wrong answer I add you are your own safety man so the answer I want to hear is "well fine but I will still be checking it" and far from being insulted when they question me I am pleased hence why I am still alive today

So do not take it the wrong way if you are questioned about how you are doing something because its not a personal attack but more of a concerned individual wanting to make sure things are done correctly remember we get posts on this forum daily from people who may want to cut corners or have a pretty neat idea how to do something and sometimes they will say "But why not" and thats fine but at the end of the day we are not reinventing the wheel

 

[Ohmyword]

Just to sober everyone up here in Glasgow today a Sherif found a "handyman" at fault for the death of a 21 month old toddler after the child put a "disconnected" oven supply cable in his mouth so heres the deal as far as I am concerned this forum is not a pi&&ing contest its for electricians to help each other out and yes there is some old heads like me are big on safety so when advice is given the person asking it needs to realise the they are tapping into a wealth of knowledge yes I know that sometimes advice can sound condisending but remember this is not a game people can and do die with house electrics and over the years every apprentice I have had I have said "do you trust me when I tell you its isolated ?" and when I get the "O yes" reply I tell them wrong answer I add you are your own safety man so the answer I want to hear is "well fine but I will still be checking it" and far from being insulted when they question me I am pleased hence why I am still alive today

So do not take it the wrong way if you are questioned about how you are doing something because its not a personal attack but more of a concerned individual wanting to make sure things are done correctly remember we get posts on this forum daily from people who may want to cut corners or have a pretty neat idea how to do something and sometimes they will say "But why not" and thats fine but at the end of the day we are not reinventing the wheel

A man after my own heart!
I tend to follow the quote of "wrong answer" with a clip round the earole just to make it certain that the message has sunk in ;-)
They can't (and mustn't) rely on ANYBODY in our trade. They MUST learn to take responsibility for their own safety in this game.

 

[impecc]

Sorry if this has been answered before. If changing a CU with 100A double pole isolator, are you saying that is not composory to compel the DNO to change the tail to 25mm2 and supply earth to 16mm2?

 

[truckster]

Sorry if this has been answered before. If changing a CU with 100A double pole isolator, are you saying that is not composory to compel the DNO to change the tail to 25mm2 and supply earth to 16mm2?

The size of the isolator is not the determining factor but the size of the fuse in the cut-out. Nominally these are 100A whilst in reality they are more likely to be 80A or even 60A. The 25mm tails debate has been stirred by the OSG stating tails should match the nominal rating. The DNO's are usually happy with 16mm as they know they will only supply an 80A fuse.If you are concerned about it you need to get a definite answer from the DNO in question.

The tails and earthing conductor are the customers/your responsibility, the DNO's won't change them.

 

[pete433]

Hi

The correct procedure should be as follows:

1 - Periodic inspection & test
2 - Remedials works repaired
3 - Fuse board can then be changed as the house will be to regs
4 - Final testing and electrical installation certificate issued.

 

[malcolmsanford]

Hi

The correct procedure should be as follows:

1 - Periodic inspection & test
2 - Remedials works repaired
3 - Fuse board can then be changed as the house will be to regs
4 - Final testing and electrical installation certificate issued.

Welcome to the forum but though a good practice not every client will pay for a PIR, and certainly on a CU change only what remedials would you expect?

What if the house installation does not have a lighting CPC, This would contravene regulation 412.2.3.2, so would you not continue with the CU change.

 

[pete433]

When a conumer unit is replaced the electrical contractor is responsible for all circuits that are distributed from it, if a lighting circuit has no CPC with class I fittings then the consumer unit should not be replaced as you are leaving the installation in a dangerous condition, unless you are willing to replace all fittings to class II and note on the fuseboard and certificate there is no earth you should not go ahead. If a periodic is undertaken first, all issues will be found, this is a transparent way of working for you and the customer.

Remember that this is standard practice, also remember that you cannot issue an electrical installation certificate with faults applied to it.

 

[nikmet]

pete, what sort of average price are you ending up at after carrying out a cu change, pir and repairs to 'standard practice' and how many hours on average do you spend without taking any faults into account?

 

[pete433]

The regulations are there to be adhered to, I have found over the years that if you give customers the right information and inform them of the correct format for a consumer unit change probably over 90% will apreciate the information and we will gain the contract. Some installs after the PIR can be a few hours work others a few days for remedial, are main concern is that the property is to regulations and that the installation certificate will hold up to regulations. The days of just slapping a consumer unit in are long gone and rightfully so. All of the relevant bodies will back-up the pir,remedial,ccu change, test procedure.

 

[nikmet]

The regulations are there to be adhered to, I have found over the years that if you give customers the right information and inform them of the correct format for a consumer unit change probably over 90% will apreciate the information and we will gain the contract. Some installs after the PIR can be a few hours work others a few days for remedial, are main concern is that the property is to regulations and that the installation certificate will hold up to regulations. The days of just slapping a consumer unit in are long gone and rightfully so. All of the relevant bodies will back-up the pir,remedial,ccu change, test procedure.

I agree 100% with what you are saying, i was just genuinely interested as to how many hours for, pir, cu change, final testing, completing certificates, I am constantly hearing of sparks doing cu change in 4hours complete, (2 a day) and I think this is impossible to do it correctly in 4 hours?