Bad Electrickery

What is that I spot? There upon yonder wall? Has someone forgotten to put a conduit lid on that box? Why yes, and the painter has dutifully included it in their efforts!

When testing a fire alarm system, my test key got stuck in a call point. Fair enough, sometimes the key can get caught on an internal spring. So I took the face off:

Only to find out that there was nothing inside!

It has been removed now, but it is very dangerous to have a call point that won’t trigger the alarm. Not good at all!

When testing a fire alarm system, my test key got stuck in a call point. Fair enough, sometimes the key can get caught on an internal spring. So I took the face off:

Only to find out that there was nothing inside!

It has been removed now, but it is very dangerous to have a call point that won’t trigger the alarm. Not good at all!

Terminating onto the sheath of the cable can be extremely destructive- the device can function when re-powered, but the poor quality connection will eventually start arcing and overheat. It can lead to problems like: What Happens When You Terminate On The Insulation

In a pub- perhaps someone stood on the flex and pulled the faceplate off. No sign of the screws though!

We at Bad Electrickery wish to present:

[right-click and choose 'save as' - 15.9MB]

This little booklet is from 1915 and describes itself as an “an Up-to-date collection of Interesting, Instructive and Highly Amusing Electrical Tricks.” So, if you’re interested in reading some early electrical experimentation, right-click on the link and save it to your desktop.

Here’s an extract:

I’m a huge fan of Prysmain/Pirelli’s FP-200. It gets used for a lot of electrical work, especially in fire alarm installation, because it is easy to strip and terminate, can take a bit of a bashing and offers fire resilience.

However, just because it’s flexible doesn’t mean it should end up in a knot.

522.8.3 -  “The radius of every bend in a wiring system shall be such that conductors or cables do not suffer damage and terminals are not stressed.” ‘Other Mechanical Stresses’ in BS7671: 17th Edition.

This can be caused by poor installation, poor fixing, or some other problem that leads to the cable ending up out of shape.

The bend radius of fixed FP-200 Gold is listed as r=6D, where D is the diameter of the cable. So, if we’re using 1.5mm two core & earth for a fire alarm system, the diameter of the cable is 8.1mm. (Source)

This means that your 90 degree turn should complete in just under 5cm, and if you were doing a u-turn, you’d need 2r=97.2mm, just short of 10cm.

Visual inspection of the cable should make it obvious if  the turn is too harsh- the sheath of FP-200 goes white under stress, and once it has been bent, will not straighten out without leaving a kink.

So these bends are probably too tight.

Part 2 to follow soon!

This looks like another case of a bad termination leading to overheating, followed by crispy despair.

Pulled out some live cables from an otherwise isolated light-switch. This is why it’s best to assume everything is live until you can prove it’s dead.

It is considered good practice to put any cut off cables into connector blocks. It is better to remove them entirely.

As far as I can figure out, this is American/Canadian cable, where black = ‘hot/live’, white = ‘neutral’ and green =earth.

In the list of things that new parents, careworkers or teachers have to think about, electrical safety is pretty near the top.

Socket covers are a commonly accepted way of making sure children don’t poke their fingers or objects into places that might be dangerous to them. However, sockets have already been designed with safety in mind, and have internal shutters that ensure foreign objects cannot be pushed in. The shutters either release on entry of an earth pin, or on pressure from all three pins of a plug.

It is possible to insert some ‘safety socket covers’ upside down, thus opening the shutters to allow access to live parts. Other socket covers leave gaps that small thin items like paper clips can be poked in. Others can be easily snapped. The plastic pins on most of the covers are not long enough to ensure they have a good grip.

Though there might be a benefit to stopping children from plugging in other appliances, without proper design and regulation, the current range of socket covers are not safe.

There is an online campaign calling for regulation of socket covers that is essential reading: http://www.fatallyflawed.org.uk/

Please sign this e-petition addressed to the UK government: http://epetitions.direct.gov.uk/petitions/36699

Telegraph: ‘Electrical socket safety covers are “absurd and dangerous” say engineers ‘ [23 Mar 2009]

IET: ‘Analysis: Engineers slam ‘flawed’ socket covers’ [17 March 2009]

Placing a socket so close to the sink would generally be considered a bad idea.

The ECA website says: “BS 7671 does not specify any minimum distance for socket-outlets to be from a sink. However, regulation 512.2.1 requires external influences to be considered when selecting equipment for a particular location. Accessories used in domestic installations are not designed to be splashed and therefore not suitable for installation close to a sink or draining board. For this reason, it is recommended that socket-outlets and other accessories should be located at least 300 mm, measured horizontally, from a sink or draining board, where they are less likely to get splashed.”

Before:

After:

Sometimes you find something that is in such a tangle, the best thing to is spend a moment fixing it down and rewiring it.

Found in a new building. A little worrying…

Originally connected to some decorative lighting, small fingers would be able to bridge live parts pulling out this American-style plug from its cheap un-fused Chinese adaptor. It was replaced with a standard UK 13A Plug.