Changing consumer unit

[bhamoggy]

If you're only changing the fuse board and not touching existing circuits, do I need to perform all dead and live tests?

This'll be my first one

Thanks

 

[steptoe]

yes,

you are altering and changing the characteristics of all circuits.

all earthing etc must also be compliant.

---------- Post Auto-Merged at 14:38 ---------- Previous post was made at 14:36 ----------

personally, I would do a few tests before I even started,

esp IR, you need to be sure your RCDs will hold in before you start messing about.

 

[kme]

Agreed -"only" changing a "fuse board" scares me a little, TBH - "only"??? - it is prob. the single most important safety device in the house. What tests do you consider un-necessary?

 

[Ali]

Hi bhamoggy,

All tests live and dead, lots before and all after the change!

My best piece of advice about your first fuse board change is to stay

calm

It seems to take lots longer to do the dead tests, remove the old board, extend half the existing cables (always seems to be needed) and mount the new board on the wall on battens or however you want to do it, with the new tails in than it does to reinstate the circuits in the new board and do the live tests.

So don't worry about time, just be methodical.

Also, if the RCD trips out with the new board in, don't forget to check where you have put all the neutrals before worrying that there is a major fault in the house! (I learned that the hard way).

Don't forget to talk the customer through what you've done and explain about RCD testing, the home for lots ofGuinnessGuinnessGuinness:Y:Yut the kettle on

Good luck, don't forget to let us know how you get on.

 

[Megaohm7]

Borrowed neutrals could be a problem with a new board going in but then again you just might be lucky. I hope you are mate. Do all your testing record your results and label up the new board and do what Ali says. Go home have a few drinks on a job well done.

 

[Hefferl]

Borrowed neutrals could be a problem with a new board going in but then again you just might be lucky. I hope you are mate. Do all your testing record your results and label up the new board and do what Ali says. Go home have a few drinks on a job well done.

Which is the easiest/quickest test method to identify a borrowed neutral?

 

[bhamoggy]

Thanks guys! Brilliant answers as usual

If there is a borrowed neutral, what sort of results would you expect to see ?

 

[Zeespark]

IR test on both light circuit lines, if all clear >999.

AndyGuinness

 

[bhamoggy]

Yes I can see how a low IR test could signify a borrowed neutral but could also mean conductors touching.

I guess there's no real way to show for sure

 

[Zeespark]

If the neutrals are shared there would be a low IR, if not, the two separate 6242YH's could potentially have quite varying differences in their internal IR when they are checked. Make a note of them. That should indicate a difference in IR possibilities when testing for shared neutrals.

AndyGuinness

 

[steptoe]

yes there is,

but if you really need to be told this then maybe you dont know enough about testing to be competent enough to change a cu

 

[bhamoggy]

yes there is,but if you really need to be told this then maybe you dont know enough about testing to be competent enough to change a cu

Possibly this so I've decided to enrol a friend to oversee while I do it that's Beem a sparks for 20 years.

I've not long done my 2330 level 3

 

[Zeespark]

A wise move moggy, ask Him whilst you are testing if He can show you the ins and outs of testing for shared neutrals, it takes less than a minute to do and not much more time to get your head around it. If nothing else, learn from the experience, its never wasted.

AndyGuinness

 

[Megaohm7]

Possibly this so I've decided to enrol a friend to oversee while I do it that's Beem a sparks for 20 years.I've not long done my 2330 level 3

It's the only way you're going to learn is to actually do it and with an experienced spark looking over your shoulder is a bonus as you can ask questions about anything you're not sure of Testing is all important. and understanding your results.You should learn a fair bit .

 

[batty]

Would insulation test find shared live if switch was off?

 

[steptoe]

Would insulation test find shared live if switch was off?

as in line or neutral ?

 

[batty]

Thinking if phase is taken from downstairs lighting circuit for landing light.

 

[steptoe]

then it would be usually classed as a borrowed neutral,

but any IR test should be carried out with switches on.

although there is a much easier / faster way of finding a borrowed neutral,

but due to health and safety I dont think we can post it open.

 

[bhamoggy]

then it would be usually classed as a borrowed neutral,but any IR test should be carried out with switches on.

although there is a much easier / faster way of finding a borrowed neutral,

but due to health and safety I dont think we can post it open.

Pm me then plz

 

[Doc Hudson]

If you're only changing the fuse board and not touching existing circuits, do I need to perform all dead and live tests?This'll be my first one

Thanks

Is there any other single item in a domestic installation that is more important to the safety of the users of the property than a Consumer Unit (fuse board)? It has been pointed out you are changing the characteristics of every circuit, as such every circuit must be verified as safe with the new protective measures you have installed. You should assume all circuits are faulty and hazardous until you have proved them safe IMHO. At which point you can then re-energise your circuits on the new CU.

Doc H.