Picture Of The Day...

[Lectrician]

Untitled

• Lectrician
• 2 Jun 2008
• 1

A nicely formed hole

Can you guess what caused this? Will post a pic with the answer shortly...

 

[Chri5]

Well it looks like it exploded from the debris and marks on the wall.

No obvious front, sides, top or bottom entry.

So I'll go with the cable entry being a clumsy hole in the wall, through which a wee mouse was stupid enough to climb in to.

The mouse created a short between some open bus / buzz, bars and the we thing blew a hole in the top

 

[Murrreid]

I'm going for someone going holesaw crazy, and hitting a live part when drilling through ?

 

[Spark123]

I'll say some faulty insulation on wires inside the box causing an arc across to the earthed metal box.

 

[Murrreid]

I am still going for the holesaw, with the use of some cutting paste, splattered over the wall.

 

[Spark123]

Amazes me how the painters managed to miss painting the galvo lid!

 

[RF Lighting]

I'm going for some singles in conduit coming out that hole.

Somehow the conduit got pulled and sheared the bush, and shorting the singles to the earthed box

 

[regsmyth]

I can't work out if the box is horizontal or vertical, but I reckon RF is right.
Someone hung something off the conduit? Like a washing line, or perhaps they used the conduit as a shower curtain rail.
Ooh the suspense!!...

 

[Spark123]

3 phase install smells of something non-domestic (notice the 440v warning sticker).

 

[breezer]

i too will go with hole cutter into something. llok at the silver dot in the middle

 

[ban-all-sheds]

The hole is too neat, and is too lacking in upwards-curving edges to have been made by an explosion from inside, unless somehow a jet of plasma was generated.

So yes - either somebody drilled into it and hit something, or the swarf hit something, or the hole was cut a while ago and possibly a black nylon gland fitted, which has now been vaporised.

Should this site be renamed CSInot?

 

[Lectrician]

It is a galv box mounted on a ceiling, jointing a 4 core 25mm SWA to some DI singles before they enter a DB - I guess the SWA was too short!

The join was poorly done with terminal blocks, and one must have worked loose. This melted, until the terminal screw made contact with the galv box, and slowly created the perfect hole.

The small 'pin' you can see in the hole is the terminal screw (or what is left of it!).

The box is right above a door, and I guess this helped the terminal loosen - the door is opened/closed very regularly, relying on the door closer to slam it!

Untitled

• Lectrician
• 2 Jun 2008
• 1

Untitled

• Lectrician
• 2 Jun 2008
• 1

Untitled

• Lectrician
• 2 Jun 2008
• 1

 

[nozspark]

Well, at least it proves that they earthed the galv box

Although why didn't the OCD go?? Bad design??

 

[Spark123]

Depends on the size of the OCD and the current flowing in the fault (arc). An RCD would have tripped tho. 25mm cable in chock block tho?

 

[Lectrician]

80amp MCCB - It did go a couple of times during the week, but they just kept turning it back on, and it held in. I noticed this above the door while going to the site for a different job!

They had not even mentioned that it had tripped until I pointed it out!