[SystemSafety] Comment on Risks note on "Smart Power Outlets" (RISKS 29.72)

[Peter Bernard Ladkin]

Concerning http://catless.ncl.ac.uk/Risks/29/72#subj2


-------- Forwarded Message --------
Subject: notsp: Re: "Smart Power Outlets" (RISKS 29.72)
Date: Thu, 25 Aug 2016 13:25:26 +0200
From: Peter Bernard Ladkin <ladkin at causalis.com>
Organization: RVS Bielefeld
To: Risks <risks at csl.sri.com>

AlMac writes "The latest gift of The Internet of Things industry, revealed last week by
security researchers at Bitdefender, is smart electrical sockets
<http://motherboard.vice.com/read/smart-electrial-sockets-could-be-the-next-botnet> that can be
hacked to hand over e-mail credentials, create a botnet,
or (potentially) burn your house down by firing up connected appliances."

Burning your house down by firing up appliances? Electrical safety standards are not perfect, but
they have been around a long time (in Germany, about 120 years). Indeed, for about as long as mice
have been gnawing through insulation on cables.

Advice to those contemplating installation of "smart power outlets" seems obvious: if you are going
to be spending on house electrics and you don't want to worry about your house burning down, then if
your circuitry is more than a decade old your "smart money" goes first on residual-current devices
and maybe arc-fault circuit breakers ("interrupters" in the US). It won't cost you much. You'll
likely have something left over for your "smart power outlets".

I have Type A RCDs on everything and was thinking of installing arc-fault protection. My electrician
looked at me as you'd look at a person who puts on a bicycle helmet to walk down the stairs and
said, quite slowly, "I can certainly do that if you wish".

Some background to all this.

Building circuits have overcurrent protection, short-circuit protection, more recently
residual-current protection of various sensitivities, and, for the cognoscenti, arc-fault
protection. Overcurrent and short-circuit protection is pretty much regulation in all developed
countries; residual-current protection increasingly so, but countries also differ on the amount of
residual-current detection/protection they require for new installations, even within Europe. I
understand regulations in the US now require arc-fault protection in some, but not all, housing
circuits in new installations. https://en.wikipedia.org/wiki/Arc-fault_circuit_interrupter
In Germany, an arc-fault protection device is called a "fire protection (circuit-)breaker"
(Brandschutzschalter), emphasising its perceived role.

Building electrical installations vary notably in age and effectiveness. It's an interesting
question to try to determine the age and adequacy of building electrics everywhere.

In a survey via questionnaire of electrical home installations in a small town, Lübbecke, near
Bielefeld, Christoph Goeker found that, of the homes of his respondents, 61% of building electrics
were older than 30 years, and only a quarter younger than 20 years.
https://rvs-bi.de/publications/Theses/Masterthesis_Christoph_Goeker.pdf (in German)

Some general figures. It is said that 93% of Italian dwellings have residual-current protection but
only 32% of French (I have no idea how reliable these figures are. They occur in the last paragraph
of Section 6.1 of
http://www.leonardo-energy.org/sites/leonardo-energy/files/root/Documents/2009/Feeds_lo.pdf
in inverse: the proportion of dwellings which don't have RCDs). Well over 60% of UK buildings have
RCDs (Table in Section 6 of
http://www.electricalsafetyfirst.org.uk/news-and-campaigns/policies-and-research/statistics/
broken down by building-ownership category) In Switzerland, apparently the figure is 100% since a
2010 law (3rd paragraph of https://de.wikipedia.org/wiki/Fehlerstrom-Schutzschalter#Schweiz , in
German).

Arc-fault detection and protection first came to the fore in aviation, after TWA 800 was discovered
to have been the likely victim in July 1996 of a fire in fuel vapors in an "empty" tank ignited by
residual current in the fuel quantity measuring system stemming from an arc fault somewhere in a
wiring bundle. Although some people didn't think so. For example,
http://catless.ncl.ac.uk/Risks/21/08#subj9.1
https://rvs-bi.de/publications/Papers/Scarry-refutation.pdf

It was regarded as infeasible to inspect all wiring bundles in all aging aircraft, and arc-fault
detection and protection seemed to be a reasonable solution. Since then, prices for arc-fault
protection have come down considerably.

Some 15-20 people die in Germany each year due to electrocution, and some 600 in building fires, of
which about a third are thought to be caused by faulty electrics (general figures from Georg Luber
of Siemens AG, the German representative on the IEC Advisory Committee on Safety), so let's say
about 200 per annum.
In the US, it seems the figure is 455 p.a.
http://www.nfpa.org/public-education/by-topic/top-causes-of-fire/electrical/electrical-safety-in-the-home

This is about the same number of people who die from the most common types of food poisoning,
salmonella (380 p.a.) and campylobacter (76 p.a.)
https://www.cdc.gov/salmonella/
http://www.cdc.gov/foodsafety/diseases/campylobacter/index.html
In the UK, it seems that the number was only 46 deaths in 2011/12, with only 25 deaths put down to
faults (Section 3 of
http://www.electricalsafetyfirst.org.uk/news-and-campaigns/policies-and-research/statistics/ )

(From these figures, the US has ten times the incidence of fire deaths from electrical faults as the
UK, with a little over five times the population. But it appears Germany has five times the
incidence amongst a population only one-third larger. So, caveat lector - something doesn't quite
seem right to me about these figures as they are - I've lived in and looked at electrics in all
three places.)

PBL

Peter Bernard Ladkin, Bielefeld, Germany
MoreInCommon
Je suis Charlie
www.rvs-bi.de www.causalis.com







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