Minor works testing

[ericmark]

You can disconnect the circuit cables from the CU and IR test them seperately without turning off the power. You can also do your continuity tests whilst disconnected. Then Zs, Ze and RCD can be measured once it is reconnected. You won't have to turn the power off as long as you take suitable precautions whilst working live. You haven't mentioned an incomer RCD, so this shouldn't be a problem.

I would not think the HSE will accept any excuse for working live on a domestic premises it is an jobs worth!

On a minor cert the only tests you are asked to do are
IR
EFLI
Polarity
RCD
No mention of Zs or Ze. Of course you need to check that the main bonding is in order.

Part 3: Essential Tests No 3 Earth fault loop impedance is surly Zs?

Cremeegg I fully agree.

Where does it say in the regs that you must issue certification when you haven't added or altered anything?
Next thing you'll be telling us you need an MEIWC to change a lamp

Scope
The Minor Works Certificate is intended to be used for additions and alterations to an installation that do not extend to the provision of a new circuit. Examples include the addition of socket-outlets or lighting points to an existing circuit, the relocation of a light switch etc. This Certificate may also be used for the replacement of equipment such as accessories or luminaires, but not for the replacement of distribution boards or similar items. Appropriate inspection and testing, however, should always be carried out irrespective of the extent of the work undertaken.

I can't see reading that there can be any way it is not required!

 

[Spark123]

This Certificate may also be used

It says MAY be used, so if someone really really wanted a certificate from me to replace a light switch then I would issue a MEIWC.
However it isn't as far as I can see, a requirement of BS7671:2008 to issue a certificate when no alterations or additions are being carried out to the electrical system and only maintenance activities are carried out.
Relocating a light switch would fall under an alteration so yes, an MEIWC would be needed in that case.

 

[luminaire]

No mention of Zs or Ze.

I too would like to take you up on this one. Even the standard IEE Cert asks for EFLI for the circuit. So that means Zs, doesn't it??

I agree, but I was rather under the impression that they were referring to Zs and Ze values for the whole installation.

By providing an MEIWC looks more professional, it is not something a DIYer is likely to do and it also covers your back should anyone come along and start complaining that since you did that job something else has gone wrong and try and put the blame on you.

 

[dave1981]

Not 100% sure but whenever we change a socket front or light switch we dont issue a certificate but i would always check water and gas is earthed and run zs and rcd test

 

[ericmark]

134.2.1 During erection and on completion of an installation or an addition or alteration to an installation, and before it is put into service, appropriate inspection and testing shall be carried out by competent persons to verify that the requirements of this Standard have been met.
Appropriate certification shall be issued in accordance with Section 631.

Verification. All measures by means of which compliance of the electrical installation with the relevant requirements of BS 7671 are checked, comprising of inspection, testing and certification.

610.1 Every installation shall, during erection and on completion before being put into service, be inspected and tested to verify, so far as is reasonably practicable, that the requirements of the Regulations have been met. Precautions shall be taken to avoid danger to persons and to avoid damage to property and installed equipment during inspection and testing.

610.6 On completion of the verification, according to Regulations 610.1 to 610.5, a certificate shall be prepared

Chapter 63 is full of references to certificate so I'll stop here. But 134.2.1 says "before it is put into service" so I would say if the repairs etc. Resulted in the power being removed then a certificate needs issuing before it is returned to service. You are correct it does not say Minor Works and I suppose you could make up your own. But somewhere there must be a document to say it is safe to switch back on.

That's the regulation but as we all know we don't always follow them and I am also guilty of fixing things without doing a full test. But I am taking a chance and if something does go wrong I am the last man to work on it. While working on commercial premises not too much of a problem but in private premises where any T D or H may have a go the Minor Works Cert is you proof it was OK after you and someone has fiddled with it after you left. In my own house different matter.

I know in my house I can only take an EFLI value on left hand RCD and any attempt doing it on right hand RCD will cause it to trip even though they are the same. So right hand EFLI is all R1 + R2 values. If an electrician had to work on my house while I was away and he presented me with made up readings I would know straight away. However in most cases no one would know the wiser and I am sure it is done all the time.

But although on commercial premises earth problems are rare although not unknown I can't believe how many houses I have visited with no formal earth connection.

So take a chance many of us do but be aware you are taking a chance. Just like speeding in your car some people seem to get away with it. But others are caught every time and you have to consider is it worth trying to get away with it.

 

[Spark123]

134.2.1 During erection and on completion of an installation or an addition or alteration to an installation, and before it is put into service, appropriate inspection and testing shall be carried out by competent persons to verify that the requirements of this Standard have been met.
Appropriate certification shall be issued in accordance with Section 631.

I don't think the direct replacement of a socket front falls under the scope of any of the following:

• during erection and on completion of an installation
• an addition
• an alteration

Hence the replacement of an accessory doesn't fall into the scope for 134.2.1.

Replacing an accessory afaik is and always has been just a maintenance activity.
A MEIWC can be issued if a certificate is requested, however there is no need to issue one.
I argee in that testing should be carried out to ensure the accessory is safe before being placed into service, but I still think there is no need to issue a MEIWC for an accessory replacement such as a light switch or a socket front.

 

[shawl01]

Guys,

Many thanks for all the responses.

I was only making the assumption about issuing the MWC because in the notes it states:

"This certificate may also be used for the replacement of equipment such as accessories or luminaires"

My main query was can I run the EFLI test while the other circuits are live? I am assuming from the feedback the answer is yes I can. Somebody please jump in quick if I have got that completely wrong.
thanks again

 

[Spark123]

Yes, you need to do the live efli testing with everything connected.

 

[ericmark]

134.2.1 During erection and on completion of an installation or an addition or alteration to an installation, and before it is put into service, appropriate inspection and testing shall be carried out by competent persons to verify that the requirements of this Standard have been met.
Appropriate certification shall be issued in accordance with Section 631.

I don't think the direct replacement of a socket front falls under the scope of any of the following:

• during erection and on completion of an installation
• an addition
• an alteration

Hence the replacement of an accessory doesn't fall into the scope for 134.2.1.

Replacing an accessory afaik is and always has been just a maintenance activity.
A MEIWC can be issued if a certificate is requested, however there is no need to issue one.
I argee in that testing should be carried out to ensure the accessory is safe before being placed into service, but I still think there is no need to issue a MEIWC for an accessory replacement such as a light switch or a socket front.

If you can replace a socket front in a manor where the HSE would allow with out removing power. Then it will not require a minor works certificate I will agree.

However if you remove power in order to do the work you need to re-commission or as it states put into service and therefore it should be tested.

I am no saying I would test every time. I am saying I should test every. time. And I think in many places the BS7671:2008 goes too far.

Basic health and safety rule. It must be written down. If I spot an oil spill and verbal report it to my boss. Then someone is injured and I go telling the HSE I had told my boss then admit it was only verbal I can get done for not reporting in writing. Any bit of paper or email what you like but any safety tests have to be written down. And that's nothing to do with BS7671:2008. It could be on the back of a fag packet but the idea is messages about safety are not relent on memory.

By all means change the socket without doing tests or sheets but be aware you should do them. At least then you have right answer if asked. "Yes I would have made one out. I must have in error thrown it away when I cleared out the van." Not "Oh I would not have bothered with such a small job" even if latter is real answer.

 

[Cremeegg]

EFLI - everything connected - yes.

However Anthony Hinsley in his book Testing Electrical Installations argues that you should disconnect the main equipotential bonding before an EFLI test. His reasoning is that you get a true figure that actually tests the earthing that is present and does not get one diluted by any external parallel paths.

Seem to remember some long discussion about this - was it here or IET forum? - time to use the search functions.

 

[ericmark]

EFLI - everything connected - yes.

However Anthony Hinsley in his book Testing Electrical Installations argues that you should disconnect the main equipotential bonding before an EFLI test. His reasoning is that you get a true figure that actually tests the earthing that is present and does not get one diluted by any external parallel paths.

Seem to remember some long discussion about this - was it here or IET forum? - time to use the search functions.

I can see some reasoning behind that idea. But unless the installation is isolated completely removing any earth connection could be dangerous both to him/herself and others. And as a Competent person I would question if one can do this.

I have had many problems with earth bonding most to do with use of welding sets and inappropriate connection of the welding sets earth which has in turn burnt out bonding earth wires. In workshops I would use 50mm earth because of this problem so it could stand welding currents.
With the modern

Isolation sign

• ericmark
• 12 Mar 2009
• 10

marked transformers it is not longer such a problem but with the old Oxford oil cooled sets the earth was required although there was a directive that the secondary should not have an earth connection there are still some old units that have not been tested correctly and still have the link in place.

What one has to remember in a commercial environment there are many items requiring an earth which may not be for normal earth bonding. For example I worked on some HF plastic welding machines and it was very important that the Faraday cage was earthed.

In the same way as he talks about parallel paths one must also consider the Ze reading and should we allow for the possibility that the supply transformer may be changed? And on a PME system if we get a Ze reading of for example 0.25 ohms should we add 0.1 ohms to the Zs reading when matching to tables to ensure should Ze be raised to the 0.35 ohm limit it would still comply?

Again may seem OK with a house but what about commercial where one item may use 100's of amps? Clearly it can't be done.

The only exception to this would be where fitting earth rods. The value for rod must be value for rod and not all incoming services as well. Again this is because the gas or water supplier may change their pipes to plastic at any time. Could this be what Anthony Hinsley is referring to in his book?

 

[luminaire]

With the modern marked transformers it is not longer such a problem but with the old Oxford oil cooled sets the earth was required although there was a directive that the secondary should not have an earth connection there are still some old units that have not been tested correctly and still have the link in place.

Could you enlarge on this for me, as we have an old Oxford welder where I occasionally work, which will need testing shortly.

 

[Spark123]

If you can replace a socket front in a manor where the HSE would allow with out removing power. Then it will not require a minor works certificate I will agree.

I won't agree with this statement at all. I would never work live unless absolutely necessary. Replacing a socket front is not one of these cases which would warrant working live.
I still do not believe BS7671:2008 asks for a MEIWC for replacing an accessory. Test all you like and produce some paperwork to keep everyone happy - we use a works control card system for maintenance work which would be more than ideal for this.

However if you remove power in order to do the work you need to re-commission or as it states put into service and therefore it should be tested.

I have never said it shouldn't be checked and tested to ensure it is safe before being put back into service, I have just said there is no need to issue an MEIWC.

And I think in many places the BS7671:2008 goes too far.

In this case not, as it doesn't require you to issue an MEIWC for an accessory replacement.

 

[ericmark]

With the modern marked transformers it is not longer such a problem but with the old Oxford oil cooled sets the earth was required although there was a directive that the secondary should not have an earth connection there are still some old units that have not been tested correctly and still have the link in place.

Could you enlarge on this for me, as we have an old Oxford welder where I occasionally work, which will need testing shortly.

I did read the directive from HSE but a long time ago. The welders sometimes had a link between the welding earth and supply earth if the welding earth was not connected correctly it could try to earth the piece being welded through the supply earth which would burn out. Never found one with this connection but I did find a few with some odd faults. On stripping I found they had been dropped and inertia has caused the wires inside to move and touch bits they should not be touching. There is no insulation inside all the wires are stiff hard drawn copper. Also the old oil was full of PCB's and now to change oil or work on you need to check what oil is in them in many cases one has to pay to get rid of them.
The oil seems to become conductive in time and does have to be changed also oil hight is important too low and it can go on fire.

As a result there was where I worked a total ban on moving them. They were pad locked to bench and if the chain or pad lock was ever found to be removed all the screws had to come out and the transformer lifted out of the oil to check the wires were not bent.

The welders would carry them on fork lifts if not stopped as they were better welders than new ones.

Once you see inside you will see what I mean. Frighting? But as long as never dropped off fork lift they are OK but no external signs of damage when they are.

I think they should be filled with FRF (fire resistance fluid) that's also nasty stuff to get rid of and carcinogenic. I had a week off work in Sizewell when some got spilt while it was cleaned up. Men in green suits had to steam clean it all off before we were allowed back in.

Spark123 I was trying to say you can't do it live without being too explicit. As I have seen sockets where the fronts are held on separate to the socket itself being a plate like used with grid switches. I could see changing these could be done without removing power. The name socket front can mean whole socket or just the plate.

I would be unlikely to make out any test sheets myself but I know I should and if I was somewhere where they followed the rules to letter then I would test. I have been on jobs where is was pass removed if found working without martindale tester and proving unit. That was Rock Savage ICI in Runcorn. And if one wanted to keep your job you had to obey the rules. In a domestic it is often very slack. And no one worries too much but on odd time you may get caught and it is important to have right answers. When I was an apprentice the old boy teaching me said when ever you break the rules think up the excuse first as if you can give it off pat it is believed but if you umm and err first rarely accepted. And I have found through the years that has been good advice.

Maybe you don't need a minor works cert but you would need something to show you had tested.

If I was caught I would say it says in the government Approved Document P that minor works are not required on page 10. Hope they would not see tongue in cheek when I said it. As I said I have all my excuses lined up just in case.

 

[luminaire]

To Ericmark: Thanks for that bit of info I'll take it up with the powers that be and see what they have to say about it.