- Reaction score
- 2,744
I know lol - have they updated their picture then on the IR test or is it still the same as the red one?
It's not always about pictures, you do realise?
Discuss Testing Questions - help. in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net
I know lol - have they updated their picture then on the IR test or is it still the same as the red one?
In the OSG (red edition) it says - main switch off .... switches and circuit breakers closed.
Yet figure 10.6 on page 84 clearly shows that the circuit breakers are open/off??
Why is this?
Am going to have a look at it again tomorrow. I know the person and am using the CU to get used to testing so have permission to probe away.
1) When testing on the remote cu do i also have the main switch off on the main Cu in the house as well??
2) And also (opposite of above), when testing on the main cu in house should remote cu main switch be off?
3) And to clarify should circuit breakers be in the off/open position or on/closed position?
So in reference to my earlier post:
1) When testing on the remote CU do i also have the main switch off on the main CU in the house as well??
2) And also (opposite of above), when testing on the main CU in house should remote CU main switch be off?
3) And to clarify should circuit breakers be in the off/open position or on/closed position?
1) you need to isolate the remote CU from being powered, as the IR test is a dead test, this depends on how the remote CU is powered eg. by an MCB from the main CU ?, if it is powered via an MCB in the main CU then this needs to be off/open.
2) depends on if you are testing both cu's together
3) this depends if you are testing all the circuits together (global) or indvidually. If all MCB's are on then all of the L conductors will be connected together via the L comb/busbar this is global, if they are in the off position you will need to test each one at the out going side of each MCB.
If it is any consolation Chrisgc, the same mistake in the diagrams is carried over in the new GN3, ie. it shows testing an individual circuit but showing all of the MCB's on when they should be off.
With regard to the above answer in red:
So doing an IR test on main cu in house AND with the remote cu main switch on - this was why I was getting a fail on my ir test between n-e?
As in post number 15 indicates that there is a fault in the outbuilding but you have indicated that the outbuilding cu main switch should be in the off position anyway (which when it is off clears the fail on the ir test)???
Richard answered this further back, You would then break the installation down further, turn off the remote CU main switch, turn all MCB's off in the remote CU, and then test each outgoing side of each MCB in the remote CU and then you will be able to identify which circuit is giving the faulty reading.
It is a question of elimination.
BTW on an existing installation it is usually better to link your L-N and test to earth in case a load is still connected, it is also wise if you are going to test between L-N to test at 250V first (soft test), in case you damage something such as central heating controllers, alarm panels, aerial amplifiers and the like which may still be connected.
OSG (red) page 84 figure 10.6 - Are the MCB's off?? It looks like they are off - are they??
But description on page 83 states circuit breakers closed (on)?
Linking L-N and test to earth - Is this perfectly acceptable if and when assessed by an assessor for competent person schemes? (long way off yet).
Yes perfectly acceptable on an existing installation, on a new build or rewire and the like you should do the L-N test on the cables before the accessories are fitted.
As I said some items don't like 500V up 'em, and it is possible to damage vunerable equipment, and on a job if you break it you have to fix it/replace it, and some central heating controller panels and the like are bloody expensive.
Totally understand about doing the 250v IR test first.
Is it not wise for electricians to have a brief disclaimer form for when assessing or testing installations (for IR test), in case something is blown due to voltage being put through?
Just a thought really as we sign forms for many things in life like operations, dental treatment etc for experts in their field to operate yet if anything goes wrong they have you sign disclaimer beforehand to cover themselves.
Would it not be an idea for electricians too and prudent in the likely hood that something was damaged by mistake?
I have just re-read your earlier posts and you say you have a N-E fault at the remote CU, as the MCB's are single pole devices turning these on or off in the remote CU won't isolate or narrow your fault down.
I would start by opening the main switch at the remote CU then test between N and E bars, if your fault is now clear then it may be a supply cable fault, if it it is still reading faulty then you will have to do as some of the other posters have said much further back in the thread, and start disconnecting the Neutrals from the N bar in the remote CU, and test each one to earth, this will at least narrow it down to one circuit, unless you are really unlucky and have more than one fault lol.
Edit: do you have any RCD's or RCBO's in the remote CU ?
Just wondering Chris, have you been taught fault-finding techniques at all, or are you learning "as you go" ? It's very important to really understand the mechanics of your system before "probing away".
Am probing only on one CU (of which I know the person and he is not in the property as of yet. So getting used to the tester I have. Was used to a megger tester a few years ago (not for long though).
I have a metrel tester at the moment. So getting used to it.
Reply to Testing Questions - help. in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net
We get it, advertisements are annoying!
Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.