#bad electrickery

[badelectrickery]

Paint My Conduit, Jim

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!

From : http://bit.ly/17vOyE1

[badelectrickery]

Calling No-one

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!

  From : http://bit.ly/1og3g81

[badelectrickery]

I Have A Crush On You

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

From : http://bit.ly/VngMWM

[badelectrickery]

Pull The Other One

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

From : http://bit.ly/W8xIlC

[badelectrickery]

How To Do Electrical And Mechanical Tricks - 1915

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:

From : http://bit.ly/XGRy6o

[badelectrickery]

The Wonders of FP-200 & Common Installation Errors - Part 1

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!

From : http://bit.ly/11c0sgD