MA: physical structure blurb

1 files changed, 26 insertions, 2 deletions

diff --git a/ma/safety_reset.tex b/ma/safety_reset.tex
index a5e5b63..70157eb 100644
--- a/ma/safety_reset.tex
+++ b/ma/safety_reset.tex
@@ -460,7 +460,31 @@ transport encryption and other cryptographic services\cite{bsi-tr-03109-2,bsi-tr
 % FIXME compare to other places where things are not as nice
 
 \subsection{Physical structure and installation}
-% FIXME
+
+Smart meters are installed like traditional electricity meters. In Japan this means they are usually installed on an
+exterior wall and need to be resistant against weather and extreme environmental conditions (direct sunlight, high
+temperature, high humidity). In Germany the meter is always installed either indoors or in an outdoor utility closet
+that is sealed to keep out the weather. In most countries the meter is connected through large integrated screw
+terminals. In the US meters compliant with the domestic ANSI C12 standard are round and plug into a large socket that is
+wired into the house or apartment's electrical connection.
+
+Modern smart meters are usually made with plastic cases. Ferraris meters often used cases stamped from sheet metal with
+glass windows on them. Smart meters now look much more like other modern electronic devices. A common construction style
+is to separate the case in a front and back half with both halves clipped or ultrasonically welded together. Ultrasonic
+welding gives a robust, airtight interface. This interface cannot easily be separated and re-connected without leaving
+visible traces, which helps with tamper evidence properties. As an industry-standard process common in various consumer
+goods ultrasonic welding is a cheap and accessible technology\cite{easymeter01,ifixit01}.
+
+Communication interfaces sometimes are brought out through regular electromechanical connectors but often also are
+optical interfaces. A popular style here is to use a regular UART connected to an LED/phototransistor optocoupler
+mounted on the side of the case. The user interface is usually limited to an LCD display. For cost and ingress
+protection smart meters rarely use mechanical buttons. Some smart meters use a phototransistor mounted behind the
+faceplate that can be activated with a flashlight as a crude contact-less input device\cite{easymeter01}.
+
+All meters provide several options for security seals to be installed to detect opening of the meter or access to its
+terminal block. The shape and type of these security seals varies. Factory-installed seals are used to detect tampering
+of the meter itself while seals made by the utility during meter installation are used to guard the meter's terminal
+block and detect attempts at by-passing.
 
 \section{Regulatory frameworks around the world}
 
@@ -487,7 +511,7 @@ Germany standardized smart metering on a national level. Apart from the calibrat
 meter smart meters are covered by a set of communications and security standards developed by the German Federal Office
 for Information Security (BSI). Germany mandates smart meter installations for newly constructed buildings and during
 major renovations but does not require most legacy residential installations to be upgraded. This is a consequence of a
-2013 cost-benefit analysis that found these upgrades to be uneconomical for the vast majority of residential
+2013 cost-benefit analysis that found these upgrades to be uneconomical for the majority of residential
 customers\cite{bmwi03,bmwi1,bmwe01,brown01}.
 
 The German standards strictly separate between metering and communication functions. Both are split into separate