Not fun: My house just short-circuited

By | October 23, 2014

A break from the usual news, with something more personal that hopefully doesn't happen every day: Kabel-BW was supposed to show up and install a cable for a high-speed internet connection on my property. They showed up fairly late towards the evening, installed the cable, and… surprise, no more electricity in the house! The installer called me in and seemed not to understand how a fuse works – he told me that the fuse looked okay, the plastic coating was still hard and there was no switch to flip. He claimed he only bored one hole in the wall, didn't hit any power mains, and that maybe something else was wrong in the house, and then left.

I asked my neighbor (who is an electrician) to have a look. My neighbor came by and tried swapping out the fuse – the old fuse was burnt through, and the new fuse blew right away as well. I interpreted that as somewhere, there was a short circuit.

After talking to customer service, who refused to do anything until an electrician had demonstrated that they were at fault, I commissioned an electrician in to look at the matter. After about an hour, he found the cause: The cable was mounted to the wall with several screws, and in mounting the screws, the installer had drilled through the main power supply for the house and inserted the screws into the power mains, causing a short circuit. The electrician removed the offending screws, and put up preliminary safety measures in place to secure the site and restore power.

So much for high-speed internet installation! But, that raises a few questions:

1) Why does a technical installer who works with cables containing electricity not know what a fuse is? I know that few houses actually have fuses these days (newer houses have circuit breakers, but older houses don't).

2) How can you short out the power main and not realize it? Usually a spark flies, and I'll bet one flew when the first screw hit the power main…

Image source: „Kurzschluss 12V20A“ von MdE (de) – Eigenes Foto. Lizenziert unter Creative Commons Attribution-Share Alike 3.0 über Wikimedia Commons http://commons.wikimedia.org/wiki/File:Kurzschluss_12V20A.jpg#mediaviewer/File:Kurzschluss_12V20A.jpg

 

13 thoughts on “Not fun: My house just short-circuited

  1. Sophie Wrobel

    +Gary Myers if you had a standard fuse there in the first place, then there's no additional risk. 🙂 But for certain uses, i.e. if you want the circuit breaker to trip when a person touches the current (as opposed to a loose wire in an electrical device or overloading a plug), you actually do need a different type of circuit breaker or fuse, which is usually considerably more expensive. Wikipedia provides a more comprehensive description of how they work:

    "To prevent electrocution, RCDs should operate within 25-40 milliseconds with any leakage currents (through a person) of greater than 30 milliamperes… By contrast, conventional circuit breakers or fuses only break the circuit when the total current is excessive (which may be thousands of times the leakage current an RCD responds to). A small leakage current, such as through a person, can be a very serious fault, but would probably not increase the total current enough for a fuse or circuit breaker to break the circuit, and certainly not to do so fast enough to save a life."
    Source: http://en.wikipedia.org/wiki/Residual-current_device

    Reply
  2. Dirk Reul

    Oh my so this is what it looks like when someone has blocked you. Well I reckon there is a reason for these things 😉
    +Sophie Wrobel it is indeed. Just look at companies like HERMES who is one of the worst places I can see someone independent working.

    Reply
  3. Gary Myers

    We unplugged an 8 amp fuse and plugged in an 8 amp circuit breaker designed to do the same job better.
    " Plug in circuit breakers are more reliable and have a faster response time then standard rewireable fuses."
    Several years later an electrician confirmed that we were actually OK for 16 amp there, and the 8 amp was probably put in when a fuse went and that was the quickest available fix.

    Reply
  4. Sophie Wrobel

    +Gary Myers oh, we have a set of circuit breakers installed after the main fuses (there are three of them). The circuit layout is something like this:
    Power Main -> Fuse -> Circuit breaker box -> Various parts of the house.

    But as +Max Huijgen points out, the fuses are there for a reason. The link you provide is to a standard circuit breaker (and is also much newer than my fuse installations, mine are all plug fuses). It will not break the circuit in time to save your life if you plugged a running hairdryer into a bathtub full of water. The fuse works more at the speed of a residual-current circuit breaker, which breaks the circuit fast enough to prevent a person testing out that hairdryer experiment. Which probably also explains why the installer is still alive.

    Reply
  5. Sophie Wrobel

    +Gary Myers Circuit breakers began picking up popularity in home installations starting in the 1960's. Before that, homes were protected by fuses (as this particular house is). There is also a circuit breaker installed after the fuse, but that wasn't tripped by the installation maneuver.

    There also happen to be different classes of circuit breakers in residential use – the 'normal' circuit breakers (which at least in Germany have been removed from the acceptable list for new installations in the last few years), the 'lifesaver' residual-current circuit breaker (previously only required for the bathroom, but for new installations required for every room), and, well, the simple fuse.

    +Dirk Reul I agree – subcontracting is much more of a problem than just skill levels. Subcontracting today is increasingly an excuse to not hire employees directly, as a subcontracted partner can be dismissed with relatively little hassle as opposed to an actual employee. (I've seen this several times now, where employees were provided an 'Abfindung' and later show up for the exact same job as a contractor or under a subcontractor instead). A dirty HR game in my opinion!

    Reply
  6. Gary Myers

    We got circuit breakers that you plug in instead of fuses.

    I'm more worried about as tradesman who drills holes in walls without checking there isn't electricity there first.

    Reply
  7. Dirk Reul

    Gosh sorry to hear that :/
    This is the result of the cable providers depending almost exclusively on subcontractors which in turn can provide various levels of skills.

    Reply

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