Testing...how far do you go?

[Dave 85]

Why would you have to start ripping circuits apart if you had 50M ohms when Ins Res testing at the CU?

Makes it sound like you ain't much of a clue about what you're on about.

If I wanted to track the 50M ohms down to a specific circuit, just so I could put 50 in the IR box next to that circuit on the cert, I'd have to pull all the neutrals outta the bar. Not always easy in an old board. If you are suggesting I put 50 next to every circuit, well, maybe you have a point.

 

[Top Cat]

As biff says i'm old school and working live has never bothered me much but have a healthy respect when doing it!

IR test L-N can be a pain. Changed a board the other day, unplugged everything and a reading of 0.02MOhms asked customer if anything still plugged in, "don't think so" but you know there is. Or it could be that you would have to pull out washing machine, dishwasher, fridge, freezer to gain access to plugs with the danger of ripping cushion flooring. I have also found the loft light is plugged in to a socket and left on. So in this circumstance if the L-E, N-E is a good reading i would probably put down 50% less than the other 2 readings for L-N. Not ideal but life isn't perfect either.

 

[telectrix]

if you get 50 meg. on a global IR test the put > 50meg. for each circuit . ssimplessss.

 

[Dave 85]

Funny how none of the people accusing me of being cowboy/danger to the general public etc can actually give an example of how something I have suggested could possibly be dangerous (to anyone other than myself).....
I'd hazard a guess that a few (not all) of them dont really understand what it is they're doing when working and are compelled to blindly follow everything they are told in order to compensate for this lack of understanding. Probably a good thing too.

Who was it that said something to the effect of...."Rules are to be followed by the ignorant and used as guidance by everybody else"?

- - - Updated - - -

if you get 50 meg. on a global IR test the put > 50meg. for each circuit . ssimplessss.

Cheers Tel, will do this in future. Never really occured to me....

 

[joe_berks]

anthony king i am going to hazard a guess that youve not done a great deal of real life testing. this man is probably a lot more experienced than you . so have some respect . what dave says is 50ohms across the whole install . you may even find that on a large enough install, every circuit is >200 individually tested, but if you test at the tails it will be reduced as it dissipates across the large area. numpty. you dont know the ways of the spark, so LLLEEEEAAAVVVEEE IT YEAH?

 

[telectrix]

back in the days before these new-fangled al singing, all dancing digital MFTs, > 10Meg. was the norm.

 

[joe_berks]

it is more suspicious to put 50 on each circuit , because 50 is an actual reading , whereas >200...

 

[joe_berks]

thorough visual, re-identify all circuits and label accordingly. Zs at origin. EFLI all circuits . Any RCBO/RCD times. Done!

 

[SirKit Breaker]

My advise to anyone thinking of working live is dont do it,especially if its not necessary

Its a shame I dont follow that advise :blush5:
I would be scared witless by someone who never works live actually doing so

Historically,electricians work has always had working live as part and parcel of the job,it is such a big no no,because of the H+S culture that is now so much more evident than years gone by

I have the highest respect for the danger of electric shock, but it doesn't frighten me one little bit,

And the good book says that "Live working should never be undertaken unless it is reasonably practical not to". Or words to that effect!

Cheers...........Howard

 

[Top Cat]

back in the days before these new-fangled al singing, all dancing digital MFTs, > 10Meg. was the norm.

Remember the wind up meggers when you could actually "feel" a fault in the resistance of turning the handle. Wish i still had mine!

 

[joe_berks]

this is reality. and the install is safe. the zs is low enough to trip the breaker in the required time. to me it is more about the visual inspection , dropping 90% of sockets switches and isolators etc and making tons of observations. if nothing is tripping out the breakers well thats your IR fine isnt it? to me that is more about testing an install before energising i would always IR test everything. but if it is on and being used already, come on man use your loaf son.

 

[Tonkatoy27]

My ELECSA assessor is pretty practical and experienced. (I should hope so) He advised me that when changing a CU to ins res all circuits at the same time, L and N bar strapped together tested to earth. If it's over 2M ohms then you know that individually they are much higher and will pass. With said example of 50Mohm then you write 50Mohm in all phase-cpc boxes, it's not false, it's what you measured albeit with all the circuits connected together. When I used handwritten test forms I'd write
L-N/CPC at the top to make it plain the L and N were strapped together when I'd done it. (more difficult with the PDF's I use now)
Agreed, L-N test is of negligible use. My assessor didn't seem to think it was important either. The risk of trashing electronic equipment far outweighs the value of the test.

I can't believe some sparkies see working live on the odd occation as such a problem, I agree they've probably had it thumped into them not to do it by the H&S ----'s. Fault finding for example is sometimes much easier live.

Well done Dave 85 for being honest and starting the discussion. We all might pick up some pointers. If you're just gonna slag people off then don't comment, it's not helpfull.

 

[joe_berks]

my friend found one in a loft, had wood panelling like in a bentley, and a luxurious leather shoulder bag

 

[Top Cat]

my friend found one in a loft, had wood panelling like in a bentley, and a luxurious leather shoulder bag

Beautiful!

 

[mark ju]

Remember the wind up meggers when you could actually "feel" a fault in the resistance of turning the handle. Wish i still had mine!

Also very useful for teaching apprentices to not be SO TRUSTING !

 

[Deleted member 9648]

If you test an entire install and get an IR of 50 megs,then put on the form exactly that. I regularly do this, and write on the first circuit detail 'IR overall reading of all circuits'.....on the second circuit IR box I write the results.....been doing this for years and our NIC bloke has always been happy.....why do you have to fill in each circuit?

 

[Dave 85]

If you test an entire install and get an IR of 50 megs,then put on the form exactly that. I regularly do this, and write on the first circuit detail 'IR overall reading of all circuits'.....on the second circuit IR box I write the results.....been doing this for years and our NIC bloke has always been happy.....why do you have to fill in each circuit?

This seems to be the way to go, Ill do it in future. Guess I was worried that I'd get pulled up for not filling certs properly by my assessor.
Out of interest do you guys RCD test every circuit on a dual RCD board? I used to but now just test one circuit on each side.

 

[Anthony King]

anthony king i am going to hazard a guess that youve not done a great deal of real life testing. this man is probably a lot more experienced than you . so have some respect . what dave says is 50ohms across the whole install . you may even find that on a large enough install, every circuit is >200 individually tested, but if you test at the tails it will be reduced as it dissipates across the large area. numpty. you dont know the ways of the spark, so LLLEEEEAAAVVVEEE IT YEAH?

You never commented on dave not testing R1 + R2, your allready at the furthest point when doing zs, so it would take 2 mins more to carry this test out, and the safe isolation procedure seems to have gone out the window, actually i do a great deal of testing for a large chain of pubs, and i know that results can be hard to obtain especially when nothing is marked up at db or at any point on the circuit. Every one has to work live at some point i dont dissagree with that.
Oh and i never disagreed with the IR test or the results either.

 

[mark ju]

Be honest here guys...When you do your testing, do you do it exactly the same as you would during a college assessment on every installation you work on/install
I dont, and I've never known a sparky who does
Feel free to accuse me of being a cowboy but here are the things I do different...

If im IR testing an old install and I get, say 50Mohms across the main Neutral/Phase and earth bars I'll write down every circuit as >200 rather than rip the fuseboard apart trying to find the circuit/circuits with less than 200. It doesn't really acheive anything IMO and takes time..
I never IR 500volts between L and N on an existing installation if the reading to earth is good, the risk of damaging the clients property is too great IMO

If im testing a new ring circuit installed by myself I'll test end to end on all 3 conductors but won't carry out cross connected ring continuity tests. On my own circuit I know its wired as a ring so this test is completely pointless.

On my own installations, if I know the chances of parallel paths etc are zero I sometimes gain my R1+R2 reading for a radial by testing Zs at the furthest point and deducting Ze. IMO this proves beyond all doubt you have a good R2. Now I know you're supposed to prove the circuits are compliant before energizing but we're all trying to make a living here and whats the worst that can happen when you know you do good connections every time and its all RCD'd

Also when I do a consumer unit change I do not test and inspect the installation to the same extent as I would an EICR. I just test ring end to end, IR L/N-E, RCD time, Ze and Zs at the end of each circuit-The going rate for C/U's (£350) does not really allow for a whole day of testing and inspection and the house is gonna be 10 times safer than before I turned up anyway.

Hopefully this should arouse some fiery debate
Seems a bit of a case of common sense vs blindly following the rules you've been given without questioning the neccessity....

You talk common sense here. Far better this than the method i once saw when working for quite a well known local contractor and that was to fill out certs, without even leaving the office!
Kind of backfired when a customer had his sparks test his property, prior to doing some work, and found a break in a ring, despite the cert showing continuity readings, Turned out a plumber had hung a radiator over a hall socket, site sparks too lazy/stupid/irresponsible to even make the most basic of checks on second fixing and the office signed it off and made up all the readings! Seen this sort of thing done by several contractors now, all on new build domestic work. Bas***s quite often get away with it!

 

[Dave 85]

You never commented on dave not testing R1 + R2, your allready at the furthest point when doing zs, so it would take 2 mins more to carry this test out, and the safe isolation procedure seems to have gone out the window, actually i do a great deal of testing for a large chain of pubs, and i know that results can be hard to obtain especially when nothing is marked up at db or at any point on the circuit. Every one has to work live at some point i dont dissagree with that.
Oh and i never disagreed with the IR test or the results either.

You've changed your tune pal....
You not gonna accuse Mark ju, Joe berks, tonkatoy27and Biff 55 of all being cowboys for more or less confirming everything I said?
No.....
Thought not.