Power loss

[ThrownRazor25]

Was out on call last night and got this job.old lady says whenever her combi boiler fires up her lights dim,she loses picture on her tv and sometimes if she is in shower the shower will fail.i tried turning the boiler on at the stat but none of the above happened.the boiler has its own circuit and is supplied from 6a mcb.i checked at fuse board and the 25mm live incomin tail was a bit slack so tightened it up thinking that because the problem was affecting numerous circuits it was a supply fault.she has phoned in today again and says the same thing about the boiler firing up.any ideas?

 

[Pete999]

Loose Neutral anywhere?

 

[ThrownRazor25]

I checked the supply cables only the live was a bit slack.only checked the boiler circuit and the spur was fine. Why would that affect other circuits though?

 

[bigdavs83]

Check the neutral busbar and make sure it's complete and not cracked or broken anywhere

 

[graham123]

Typical loose neutral, If its a Hagar board neutral bar links seem to fail on them somtimes.

 

[mechelec]

Sounds like it could possibly be a DNO fault ie joint/connection breaking down under load. What was the Ze measurement ? Test between live and earth and live and neutral on incoming side of CU. Should prove or eliminate external fault.

 

[wozz]

is it a electric boiler?

plug your tester in and look at voltage start loading installation kettle, hob ect if the voltage plumets you may well have a neutral problem at a common connection at fuseboard or on supply side.

 

[ThrownRazor25]

It is a combi boiler going back tomorrow morning so hopefully get in about it and try and identify where the problem is.

 

[Guest111]

had something similar on our house years ago,VD was taking it down to around 150v,turned out to be a dno issue.

 

[ThrownRazor25]

Out here just now ze is 0.13 tncs system tried turning the boer on but nothing's happening voltage is going from 235 to 240

 

[ThrownRazor25]

Test between l and n on the flex supplying boiler on ohm meter getting 130ohms

 

[Guest111]

Where are you?

 

[ThrownRazor25]

Denny near falkirk not rural small town.

 

[mechelec]

Ze good so fault is internal ( pme assumed). Is circuit supplying boiler only circuit with high N-L impedance ?

 

[ThrownRazor25]

Zs for boiler is 0.86 cooker 0.33 sockets 0.54 lights 0.79 shower 0.4
the fault has never happened while I'm in the house