[SystemSafety] Electrical Safety, Fire Safety

[Peter Bernard Ladkin]

On 2017-06-16 10:22 , GRAZEBROOK, Alvery N wrote:
> I'm not sure what the regulations require, but I note that my previous consumer unit (installed about 20 years ago) was as you describe, with RCD protection on the power circuits, but not on lights and smoke-detectors. When I re-did the kitchen a year ago they replaced the consumer unit, which now has RCD protection on everything. 

Some literature says devices with so-called "inverters" can trip RCDs when unnecessary. Daniel
Grivicic pointed out to me privately that he has experience with this (he's in Australia) with air
conditioners. The IET also has some old correspondence on the issue from 2010
http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=35587
However, as I said, Type A RCDs are the law in Germany since 2007.

The easiest way to reconcile all this is to assume that modern RCDs are more dependable than they
were. This is consistent both with advances in electronics along with the assumption that the
manufacturers of RCDs would be motivated to eliminate false-trip issues and they certainly have the
technical wherewithall to have done so.

On another matter, after the Fukushima accident in 2011 there was sudden interest, at the level of
states, in investigatory robots. They used devices from iRobot and Qinetiq at Fukushima, but of
course they had real problems with the effects of the radiation on the electronics. There quickly
seemed to be state money in the key countries for promoting and developing the technology further.
Six years later, are such robots available to investigate the Grenfell Tower wreckage, said to be
unstable? If not, shouldn't we try to ensure some are available for the next disaster in enclosed
spaces?

Issues about building safety are difficult. I have my problems nowadays with large buildings and
escape routes when I am staying in hotels. Newer ones mostly seem OK, but I am also aware that
evacuation is still more art and luck than science, as Chris Johnson showed a decade or so ago. It's
a key business in ship classification for cruise vessels, but even so it doesn't work super-well, as
we learnt with the Costa Concordia. You have potentially 5,000-6,000 people on some of the newer craft.

Besides electrical safety, the issue of fire-resistent cladding is not new. The issues of sprinklers
in large buildings, and appropriately-functional evacuation routes, are perennial. Evacuation is a
tricky business, as Chris Johnson and Karster Loer know. Karsten, BTW, drew up the evacuation plans
for a open-air rock concert last year, at which there was a violent storm on the first day and
everyone was evacuated. It's nice to have it proved that your plans work! Evacuation and crowd
control came into prominence in Germany with the Love Parade disaster in Duisburg in 2010.

In Germany, smoke alarms must be installed in all bedrooms as of this year (before, the reg was just
for newbuilds). I installed them in the appropriate strategic places in my building when I bought
it. I have tenants who live on the first floor in a rear apartment whose appropriate means of escape
seem to me to be out the bedroom window onto the roof, whence it is 3m onto the soft garden surface.
From three meters, you have to know how to land in order not to break anything, but it's not
life-threatening for most youngish, moderately active people. I sleep on the second floor of
another, higher part of the building. It's four meters down from the window to the balcony, and
there is a steel bar installed on the frame (to hinder my then-young son and pals from leaning out
too far) which can be used for abseiling. I keep a climbing rope to hand. On the other side of the
building, it's twice as far to the ground (no balcony) but that's no problem in principle.

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
MoreInCommon
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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