I'm Completely Mystified. C.U. Problem

[john a. page]

I would welcome some advice please with an ongoing problem I cannot currently resolve.

My property consists of a mid 50's bungalow with a self build extension (Not of my doing I hasten to add!) Since moving here I have experienced the occasional problem of blowing light bulbs, which in turn trip the circuit in the C.U. Usually just replacing a bulb and reseting the trip does the trick.

However yesterday, I had a similar problem but I cannot reset C.U., which continually trips. The circuit effected consists of 4 ceiling lights, but having disconnected all of them, including the switches, I still have the problem. Even with the main circuit breaker switched off the offending circuit cannot be reset.

The wiring is nothing like what I expected to see and seems to consist of a large collection of junction boxes with wires going in all directions making tracing cable routes almost impossible.

Does anyone have an idea how I can resove the problem please?

John.

 

[ProDave]

If it won't reset with the main switch off, then it's NOT a wiring fault causing overload, but a faulty MCB.

SOME mcb's you need to push the lever DOWN first before you can then push it UP to turn it on. Try that. If that doesn't work the MCB needs replacing.

Put all the wiring back as it was.

Blowing bulbs is a common complaint, but contrary to popular belief, it is rarely caused by an electrical fault, it's just that most bulbs on sale these days are simply cheap rubbish that doesn't last long.

 

[Riggy]

If the MCB (circuit breaker) for the circuit won't reset even with the mains turned off I'd be 99% confident you have a faulty MCB.

 

[Andy™]

as above - sounds like the MCB needs replaced

 

[binky]

....or there is a fault with the circuit.Suspect something to do with JBs in attic. Call sparky to resolve if not confident to deal with issue.

 

[M107]

Went to exactly this type of fault yesterday evening....

If its a 1950's property do you have those (BS3871) mcb's with a circular button & a smaller button below? if so tap the mcb gently & odds on it will reset.....the functional trip button doesnt always latch back in.

If you do have those types of mcb's I would advise upgrading them to the modern BS 60898 lever type mcb's

 

[Revved Up Sparky]

Blowing bulbs is a common complaint, but contrary to popular belief, it is rarely caused by an electrical fault, it's just that most bulbs on sale these days are simply cheap rubbish that doesn't last long.

+1, and furthermore I would suggest that worn out lampholders can sometimes be the problem too. Poor spring tension in the pins making contact with the bulb can cause a lot of extra heat to build up. I would try higher quality lamps and if that does'nt cure it, change the lampholder.

 

[M107]

Talking of not so cheap, but are rubbish lamps....dont bother buying the B&Q Halogen GLS lamps.

I had a customer complaining that after only being on for a short period her lamps kept blowing.

Experimented by putting them in the pendants down stairs & got the kids to play rough & tumble upstairs, those below the kids rooms packed up very quickly. I suspect the lamps get hot & the slightest vibration ..pop out they go.

They might use 22% less energy but not so good cost wise when they have to be replaced so often.

 

[OnOff]

The last "non resetting mcb" prob a I was asked to look at was a combination of rat damaged cables AND water ingress to a jb. They had chewed the ring cable on the edge of a flat roof - the facsia board was rotten allowing them and the rain in. The sheath had been chewed along with the live (old red & black). The exposed copper inside the live had gone more blue than green - so bad that looking in, at first glance I thought it was the neutral! 32A mcb would hold in for a couple of seconds then pop. AND the rcd didn't work!

 

[M107]

I took the thread to be: the cu is isolated but the mcb still will not reset.

 

[kerching]

at a guess [and it is a guess as I have not seen the job] it is probably a faulty MCB. If the MCB has a history of blowing , then it has probably gone all moody on you. If however you are unfortunate enough to have a Wylex MCB that wa missed on the recall, then be very afraid... :coat

 

[john a. page]

The unit is a 'HAGER'. I've tried all the suggestions to no avail. Looks like I need a sparks then? By the way, I see no evidence of rodent activity either inside, or outside the roof area, but it's worth investigating as the insulation is a foot thick!

 

[Andy™]

unless you know how to change an MCB, then its probably best call a sparky. if it is just a faulty MCB, then its a fairly straight forward job

what area are you in? there may be someone here local to you

 

[john a. page]

Andy,

I'm just outside Leighton Buzzard, in Beds,

 

[batty]

Hager stuff is good but I have replaced a few MCB's and quite a few have been Hager.

That doesn't sound right I think since I have been trading I have replaced about four Hager MCB's as they have failed.

 

[steptoe]

Completely off tangent, do you have solar PV? Hager have known issues with PV installs.

 

[kme]

If you want one; I can recommend a spark in Leighton Buzzard -they don`t generally do domestics; but I think he would if you mentioned me.........

PM me if you want the name