How many times have you been called out to a place to find that, the only reason you are there, is because, the person who done the installation work, never done the screws on the fitting(s) up properly?.
I went to a house, this morning, way out in the middle of nowhere, fed with 3phase,
the customer reckoned they smelt something burning around the general area of the s/board, I got there and opened up the board and the feed wires fell out of the bottom of the Main Switch,BOOOMM!!.
A Phase-Phase Short!, like to get a hold of the person that was responsible for this one.
Have you seen anything like this before?,
Or even your own experiences with loose wires,please go forth-

Trumpy.
to many times mate, far to many times.

just one ( of many ) time comes to mind,

I was called to a bakery in the centre of a large city,
our company had originally wired the site (on two floors) the supply was 600 A per phase, supply comes in from the road into a rather large (1000 A) disco then to a bussbar chamber to three 24 way DBs one feeding all the main high loads and the other to lighting and general power (big building.

I was called in on a weekend, as i was the engineer on call, to find out, and i quote,

`why the lights are flickering and all the ovens keep on reseting there timers`, ` what have YOU done to our electrics`,

You know what i mean on that one, all of us do !

So first things first, open up the DBs one by one, and have a look, well nothing wrong there,but at the disco i noticed another cable coming out, thinking, that dont look right, walks over to have a better look, moved a bit of 4 x 2 that was in the way, it hit the `new` bit of cable, it exploded, i hit the deck, and woke up in the ER. !!!

the long and short of it is,

there `Maintenance man come janitor wanted a new supply for his tempory cabin outside and decided that instead of calling the EC he would Wire it himself,

our company is in the prcess of a court action, and he is not employed any more,

the repair job/loss of trade/accident claim etc etc is gonna cost the firm about $190,000.!!!!

people should not tamper with electricity, we are trained time served and capable, also licensed ( well you are in the US but we are not in the UK .........Yet )

I move fixtures and have wires just fall out on a regular basis, although not always quite so dramatically as in your example!

I once had the PoCo's main neutral just pull straight out of the connector block when I moved it slightly.

YIKES !!
It's far to common everywhere.

JH,
Are you OK, now?.
That sounds to me like a real shocker!.
I certainly agree with your comments about leaving Electrical work, to those that are trained and qualified, to do so, this could save a lot of Electric shocks, Fires and general property damage.
I've found over the years, that a lot of Engineering and General Maintenance staff, are working too far, out of their skills base when they start hooking up 3-phase equipment
and controls.
Recently, I had a callout, to the local Meat-Works, to repair a Backing Saw(splits Pig carcasses in half and it is the most vicious looking machine I have seen yet).
But, long story short, it was running backwards(and no, it was not joining the pigs back together), but it did nearly take the head off a Slaughter-man, only because one of the Maintenance men(?), didn't know about Phase Rotation of 3-Phase equipment,
he assumed, that no matter which way the feed was hooked up, the saw would turn the same way, as it was fed through a gearbox.
Still haven't worked out, his line of thinking on this one.
One thing I do know, is that, assumptions are the Mother of all F*** ups.

[This message has been edited by Trumpy (edited 01-18-2003).]

Recently renovated School building. Circular saw in woodworking class, dedicated 16A 3ph circuit. Teacher wondered why saw worked so poorly. Opens receptacle, phases swapped. lol!
Concerning loose screws: Take an old switch out of the box or open a plug, and chances are good at least one of the wires will immediately fall out of the screws. In the Villa I mentioned in the DC system post EVERY switch had at least one loose wire.

Texas,
Over here, we have a thing called Visual Inspection, as part of the testing regime,
before an installation is first energised, this entails, giving the wires in the gear that you have just installed, a wee pull, to make sure they are tight, in thier terminals,
but some people are just not playing the same game over here.

Personally, I think that those screws get loose with time. This is especially true in panels with breakers where the heat/warmth which is emitted can cause those screws to loosen up.

Well, remember, here in Austria a sparky's work is not inspected. Every sparky is his own inspector. The switches I mentioned were replacements, so probably they just sent out an apprentice. Yes, maybe the screws become loose, but it varies remarkably. Some old screws are still perfectly tight, sometimes there are tight and loose screws within one switch box.

Yes, you're right Ranger that it varies remarkably. I am one who always makes a point of tightening screws very very strongly (sometimes untill they snap in half!(I have encountered this problem only with screws of contactors which have thinner screws. Let me add that I always get a replacement in such a case under the manufacturers warranty))
I was once called to a place where a whole RCD melted b/c of sparks that were created b/c of loose screws. It melted untill it made a short and the MCB tripped! I find that it would be a good idea to make RCD's with a thermal protection, too. I think that that's how a lot of fires (which are due to electrical fault) start.

Damn Right, Belgian!.
I fail to see, how a screw can "un-tighten",
itself, provided that copper wires are used
and the screw is properly torqued when it is
tightened.
This whole loose terminal screw thing makes me think, that one type of Electrical worker, may be to blame for it, who could this be?, The One Screw-driver Sparkie,
their tool-kit consists of a pair of screwdrivers(1 flat blade,1 Philips), a pair of Pliers and a test lamp.
What are your thoughts on this idea?-

I don't think the screws untighten as such, but I do think connections can become loose where there is temperature cycling, due, I believe to "creep" of the relatively soft conductor metal under pressure. A particular example of this is where stranded flex of appliances used to be supplied with the ends solder tinned for ease of fitting the plug. This often used to lead to bad connections after a time.
Further thought -- Once the tightness in a connection is lost the resistance will rise leading to greater resistive heating, so perhaps there is some sort of exponential effect here until heat damage or failure due to open circuit occurs (??).

Geoff,
Welcome to ECN!.
Our Regs over here in NZ, actually prohibit the fitting of soldered wires, of any size, to screw type connections, mainly because of the heat produced by such a bad connection and the subsequent falling out of the wire, when the solder melts.