No power to immersion

[HappyHippyDad]

Morning all.

I have just been to a house where there is no power to the 13A FCU feeding the immersion.

I believe I have found the corresponding MCB in the CU although it is difficult to be sure as there is only continuity on the CPC, it is labelled water heater. There is no continuity from the CPC in the FCU to any other CPC's in the CU which also makes me think I have located the correct MCB.

It has not been working for around 6 months. The tenants say no work has been carried out and it just stopped working one day.

It does seem odd that there is a completely clean break between line's and neutral's (L-L >999Mohms, N-N >999Mohms) of the cable and the CPC is intact, barring any parallel paths (unlikely).

I have searched everywhere for a DP switch or timer switch but cannot find one. The tenants say there isn't one and the landlord is unsure.

Am I missing something obvious? The reason I ask is because I will be putting a new circuit in (easier than taking carpets/floorboards up to find fault) but it just seems like there must be another switch somewhere and that's a lot of disruption for the sake of flipping a switch!

 

[pc1966]

That is a very inventive solution to not having TDR equipment to hand, shame it is no longer possible in the HDMI era!

Sometimes you get really odd results and then discover that you actually have a really odd setup. In one case I guy I worked with was deeply puzzled by some results and then pulled up the false floor panel to discover that yes, there really was 100m of cable between two racks barely 1m apart!

 

[Mike Johnson]

Tried various cables and permutations with no useful results, I don't think the 760-1 is sensitive/sophisticated enough, but an interesting exercise just the same.

 

[pc1966]

Tried various cables and permutations with no useful results, I don't think the 760-1 is sensitive/sophisticated enough, but an interesting exercise just the same.

Well that is at least useful to know, so unless someone has the '2' version of that meter or better it might not be usable.

I realised the cable I checked earlier was actually Doncaster 1.5mm T&E, found the Prysmian 2.5mm off-cut and it is 141pF/m for phase-earth, and 243pF/m for L+N -> E

 

[Lucien Nunes]

I have spent quite a bit of my life troubleshooting under pressure, sometimes in adverse conditions. You get creative or get fired.

 

[static zap]

I had access to a computer and a monitor but no test gear.

This could have been my best excuse for keeping a larger CRT monitor !

 

[Baddegg]

That's bloody creative is that.

I remember teaching him that trick...

 

[GBDamo]

had somewhat similar recently. there was a 20A D/P switch in the kitchen. customer used to leave the FCU in the airing cupboard permanently on and use the kitchen switch. the fault was O/C pole in this switch.

Had exactly the same, one FCU in the airing cupboard and one in the under stairs cupboard.

The tenant pointed it out to me as I was busy pulling my hair out.

 

[Lucien Nunes]

I remember teaching him that trick...

And provided tomorrow doesn't turn into too much of a mare (which I'm half expecting) I'll rig you all up a demo.

 

[Lucien Nunes]

I've even found the original butchered cable, but it turns out the monitor I was going to use doesn't have a VGA input as I had thought, so I'll have to do it tomorrow.

 

[MJPD29]

had somewhat similar recently. there was a 20A D/P switch in the kitchen. customer used to leave the FCU in the airing cupboard permanently on and use the kitchen switch. the fault was O/C pole in this switch.

Had that before as well. However is want an open contact in switch. The tenants just hadn't turned the switch in the kitchen on as they didn't know what it was.