electric meter issue. The grid, meter or consumer unit issue?

[ian burnett]

Hi Guys, I've made this video (link below) to highlight an electric issue in my house. I wonder if any of you know what the issue is? I am going to call out an electrician but I would love to know your thoughts. Thank you for your time Ian

 

[Gavin John Hyde]

Regardless of cause i think the forum now needs a new rule that you require a video of the fault or problem to explain it better.
Can we give the op a special badge on his name for his efforts as that video was very good.

 

[snowhead]

It's got to be Best explanatory video ever, certainly on any forum I've ever been on in the last 20 years or so, or whenever it became possible to upload video to a forum

 

[FatAlan]

I’ve found that if you contact the DNO online and include the words ‘fire’ and / or ‘explode’ you get quite i quick response. N.B Not sayinging that’s an issue in this case. I had a problem with a faulty meter and was going round the houses with the supplier. Tried to contact them online and just added that I was scared that it was faulty and might catch fire. Funnily enough I got quite a quick response. Reckon they must have a key word filter on emails to prioritise.

 

[DPG]

Fiver says it's a broken neutral in the joint box under pavement where house is tapped off.

 

[freddo]

Same fault I was called to with the disco shower. My video was slightly less professional...

Loose neutral on supply cable joint just outside the house.
I should also note that in this condition any earthed/bonded metalwork will have a voltage (possibly quite a tingly one) on it!

 

[DPG]

Disco shower - no way am I clicking play on that video!

 

[Lucien Nunes]

SC said 'loose connection' in the DNO's equipment in post #2 and I totally agree. A loose connection in the service cable joint for example. But others have gone on to be more specific by saying it's the neutral. Why? What evidence do we have that the neutral is faulty and not the line?

We've had a discussion with lots of good ideas about why high resistance connections are (thought to be) more common in neutrals, specifically in domestic installation work. Explanations include sparks habitually wiring the line first, then doing the neutral with waning concentration; or manufacturers using terminals of inferior design in CU neutral bars, etc. But does this apply to DNO equipment too, such as service cable joints? Where CNEs are terminated they have to be extra vigilant about continuity, so I'd almost expect a higher rate of failure in line connections.

Thoughts?

OP: I'd call the DNO. The problem is theirs, not yours, the meter display showing 'Low U' is a dead giveaway.

 

[DPG]

SC said 'loose connection' in the DNO's equipment in post #2 and I totally agree. A loose connection in the service cable joint for example. But others have gone on to be more specific by saying it's the neutral. Why? What evidence do we have that the neutral is faulty and not the line?

Have seen it happen a couple of times on my local estate alone, and both times I have spoken to the network guys and they confirm it is a common thing, mainly on joints from the 1970s. Didn't ask them their thoughts on why neutral, but wish I had now just out of interest!

Both times the symptoms were the same (flickering lights when other loads switched on, raised voltage on exposed metalwork, etc.).

 

[TJ Anderson]

100% is upstream of Meter as already said so it's the DNO issue to resolve. Could be line or neutral but frankly who cares at this stage......call the DNO and report it.

Awesome video OP

 

[Bobster]

SC said 'loose connection' in the DNO's equipment in post #2 and I totally agree. A loose connection in the service cable joint for example. But others have gone on to be more specific by saying it's the neutral. Why? What evidence do we have that the neutral is faulty and not the line?

We've had a discussion with lots of good ideas about why high resistance connections are (thought to be) more common in neutrals, specifically in domestic installation work. Explanations include sparks habitually wiring the line first, then doing the neutral with waning concentration; or manufacturers using terminals of inferior design in CU neutral bars, etc. But does this apply to DNO equipment too, such as service cable joints? Where CNEs are terminated they have to be extra vigilant about continuity, so I'd almost expect a higher rate of failure in line connections.

Thoughts?

OP: I'd call the DNO. The problem is theirs, not yours, the meter display showing 'Low U' is a dead giveaway.

Not necessarily the joint in the cable where the neutral fails being more common.

However further back to the transformer sees quite often the star point connection failing, especially on smaller transformers.

Most DNOs as standard are fitting K Type transformers now with a 200% FLC rated star point connection.

These are failing due to the sharp increase of harmonics being put onto our distribution network.

 

[ian burnett]

Thanks for all your input guys. The grid guys came out last night and repaired it. It was a faulty Neutral

 

[wheeto]

Thanks for all your input guys. The grid guys came out last night and repaired it. It was a faulty Neutral

Fantastic!

 

[wheeto]

Most DNOs as standard are fitting K Type transformers now with a 200% FLC rated star point connection.

Hi Rob! That's something beyond my area of expertise .... What is a "K Type transformer?" Or are you just saying it's a tx rated for a K factor of 2?

 

[Bobster]

Hi Rob! That's something beyond my area of expertise .... What is a "K Type transformer?" Or are you just saying it's a tx rated for a K factor of 2?

A "K-Type" Transformer is a generic name used for a transformer that are designed to reduce the heating effects of harmonic currents. The K-factor rating is an index of the transformer's ability to withstand harmonic content while operating within the temperature limits of its insulating system.

The ones I have seen the DNO fit, and a few I have overseen installed, along with better quality insulation, offered a greater sized star point connection. (200% greater than the phases).

Because of the phase angle change by the transformer (most DNO transformers supplying LV have a DYn11 vector group). Harmonics can not pass through to the primary side. An thus the transformer needs to take the brunt of it.

 

[DPG]

Thanks for all your input guys. The grid guys came out last night and repaired it. It was a faulty Neutral

Nice one - whereabouts?