Exploding BT socket and a lucky escape

[jamieled]

Had a weird one this morning, and possibly quite a lucky escape. Got distracted from work by a loud bang. Power went on/off quite quickly. Anyway, the BT master socket beside the CU exploded with a bit of smoke. Cue two fire engines, SSE and the electrician coming to have a look.

 

Anyway, what looks to have happened is a buzzard hit the pole mounted transformer that supplies our house and caused a large voltage spike. This then somehow travelled through the broadband router which was plugged into the BT openreach socket. As this master socket is also connected to another phone socket it managed to gub that as well. Pictures below. I've asked SSE to put a guard on the transformer to try and stop this happening again.

 

Most of the electrics are fine, though there is a bit of damage to an electronic boost switch and the pv diverter, presumably because they have relatively sensitive electronics.

 

 

 

 

 

 

 

 

[Big Jimbo]

Don't expect the Buzzard enjoyed it much either.

Edited September 16, 2020 by Big Jimbo
m

[Temp]

20 minutes ago, jamieled said:

Anyway, what looks to have happened is a buzzard hit the pole mounted transformer that supplies our house and caused a large voltage spike. This then somehow travelled through the broadband router which was plugged into the BT openreach socket.

 

If that's really what happened I'd check every electrical device that was plugged in at the time.

 

[jamieled]

@Temp the electrician had a pretty thorough check of everything. The damage was limited to anything plugged into a phone socket (router, phone) and a couple of electronic switches. Luckily we don't tend to have a lot plugged in so that probably helped.

 

[scottishjohn]

don,t think SEPA will be very happy if they find out a buzzard could get fried on a power pole

must be something wrong with the installation --lots of buzzards round here never seen one get fried -and they do like to just sit on poles and watch 

[joth]

RIP Buzby

 

 

 

[jamieled]

@scottishjohn yeah we see them on the poles quite a bit round here. SSE are claiming it's just unfortunate the bird managed to create an arc between two bits of the transformer.

[Onoff]

1 hour ago, jamieled said:

@scottishjohn yeah we see them on the poles quite a bit round here. SSE are claiming it's just unfortunate the bird managed to create an arc between two bits of the transformer.

 

Did it smell like KFC?

[Temp]

I'm not totally convinced by the explanation. If the mains voltage shoots up there should be sufficient isolation in the router power supply that its not transferred to the telephone line.  

 

 

[jamieled]

30 minutes ago, Onoff said:

 

Did it smell like KFC?

KFB (Kentucky Fried Buzzard)

 

Actually didnt look that fried in the end.

[Mr Punter]

It really looks like the BT was livened up.  Is the BT near the pole outside where the buzzard bought it, or must it have happened in the router?

[jamieled]

The BT is nowhere near the pole - even where it comes into the house it's separate from power. Had another engineer type out tonight who says he's seen a few similar and reckons the high voltage came via a plugged in cordless phone (which also blew it's plug) into the phone line and back to the openreach socket.

[ProDave]

The description of this puzzles me.

 

How could a buzzard flying into the transformer cause this?  The only concevable way is if it bridged between the 10kV incomet and 240V outgoing.  But I would expect the buzzard to be severely charred and all the house electrics to have flashovers at multiple points and just about anything electronic blown.

 

Does the BT come in above or below ground?  I take it the BT line is toast and OR need to repair it?

 

It sounds to me more like there was somehow high voltage on the BT line and the fact you happened to find a dead buzzard outside just after was coincidence?

[Mr Punter]

This has al the makings of a crime thriller plot.  Did the buzzard have a Russian accent?

[jamieled]

@ProDave Might just be my description!

 

BT line comes into the house through the founds but the cable sits on the ground surface where it runs down to the junction box beside the road. The bt cable in the house looks like toast (both master socket and one other internal socket with phone connected). Couple of other bits of damage to electronic timer/boost switches.

 

SSEN were out repairing the transformer last night as it blew some kind of fuse when this happened, normally designed to protect the transformer from lightning strikes apparently. Although I can't explain exactly what happened to the bird it seems too much of a coincidence that the transformer goes bang at the same time as the bird touches it and our bt socket also blows?

[jamieled]

@Mr PunterI have left out the juiciest details to make sure nobody steals the film rights.

[Big Jimbo]

7 hours ago, Mr Punter said:

This has al the makings of a crime thriller plot.  Did the buzzard have a Russian accent?

I think the Russians tend to use Albanians these days for the simple jobs. There prefer to be able to keep some distance.

[dpmiller]

I'd suggest there's something dodgy on the earth side of the pole transformer which could then allow local ground (and your neutral in the house) to rise towards the potential of the overhead line because of leakage through the bird?

 

edit: which if any of the trips in the house had gone?

Edited September 17, 2020 by dpmiller

[jamieled]

9 minutes ago, dpmiller said:

edit: which if any of the trips in the house had gone?

Don't think anything tripped in the house but I wasn't the first to look at the CU so could be wrong on that one.  Earths were checked afterwards by SSE and the electrician and found to be fine.

 

The power went off and on again immediately after the bang, but I think that was just the usual network operating process - it's done it in the past when a tree hits the line.

[ProDave]

2 hours ago, jamieled said:

@ProDave Might just be my description!

 

BT line comes into the house through the founds but the cable sits on the ground surface where it runs down to the junction box beside the road. The bt cable in the house looks like toast (both master socket and one other internal socket with phone connected). Couple of other bits of damage to electronic timer/boost switches.

 

SSEN were out repairing the transformer last night as it blew some kind of fuse when this happened, normally designed to protect the transformer from lightning strikes apparently. Although I can't explain exactly what happened to the bird it seems too much of a coincidence that the transformer goes bang at the same time as the bird touches it and our bt socket also blows?

What I am trying to understand is how the high voltage got onto the phone line.  i.e. does the phone line originate as an overhead on the same pole?  If it is underground and totally away from the electric I can't understand how it happened.

[joe90]

1 hour ago, ProDave said:

I can't understand how it happened.

As an ex BTman, nor can I, historically sockets used to have a small gas discharge tube to absorb lightning or high voltage, but as they were very small I am not sure how well they worked. Looking at your master socket the force came from terminal 5 ( one leg of the incoming line) and left side of cct board where there is  nothing, guessing it could have leapt to the face plate screw in that area which will be earthed!!!!,

Edited September 17, 2020 by joe90

[jamieled]

SSEN sent someone out last night to do additional checks and to arrange repairs. Apparently they do this all the time where voltage faults have caused damage.

 

His working theory is that it was more likely the voltage spike came from a phone plugged into a socket elsewhere in the house. This then transferred into the cat5 connected to the bt master socket shown above. His reasoning for this is that the power plug on the phone was blown while the router power plug (connected to the master bt socket beside the cu) was fine. The base station for the phone also shows damage. He didn't seem that surprised by what had happened.

 

Pic shows the phone 3 pin power plug and the back of the bt faceplate it was plugged into.

 

I'm quite grateful that metal CU was in place. Not sure we'd have had the same outcome if it had been plastic.

[joe90]

That sounds plausible!. Don’t see why a plastic CU would make any difference tho? @ProDave ?

[jamieled]

@joe90 there is a large scorch mark on the side of the cu where the bt socket went pop. Not sure a plastic cu would have been as robust.

[ProDave]

6 hours ago, joe90 said:

That sounds plausible!. Don’t see why a plastic CU would make any difference tho? @ProDave ?

I still do not see anything in the picture of the CU posted to suggest this originated via the mains supply. So in the absence of any explosive issues within the CU I dount a plastic one would have faired any worse.