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- Committer: Kevin Cole
- Date: 2005-12-22 00:40:58 UTC
- Revision ID: kjcole@gri.gallaudet.edu-20051222004058-f53cb6abfc942af7
Making a few files validate against lore
added
removed
lore/chap05.lore
5
5
6
6
<body>
7
7
<h1>Lab layout [5]</h1>
8
</p>
9
10
<p>Before you carry a lot of computers into a room, there needs
11
to be a good deal of preparation. A classroom will need to be
12
modified to include special features, such as a lockable
13
cabinet to secure the switch and server, and a layout that
14
accommodates the re-arrangement, addition, or removal of
15
furniture. Electricity is another consideration: every
16
computer needs power, and in order to protect them from power
17
surges, the computers need to be on a separate power circuit.
18
</p>
19
20
<p>Security is also an important consideration, and will involve
21
at least burglar bars on the windows and an alarm system. The
22
exact security measures that should be taken will differ from
23
school to school. Several factors should be considered: for
24
example, the known crime rate in the area, the isolation of
25
the school, and the affordability of the security measures.
26
</p>
27
28
<p><img src="illustrations/lablayout.png">
29
_________________________________________________________
30
</p>
31
32
<p>5.1. Security [6]
33
</p>
34
35
<p>Here are some guidelines to consider when selecting a room for
36
an Edubuntu lab. They aren't hard and fast rules, and when you look
37
through them, you'll notice where there's room for initiative.
38
They should however be taken as a baseline to improve upon
39
where there's opportunity.
40
_________________________________________________________
41
</p>
42
43
<p>5.1.1. Window security
44
</p>
45
46
<p>Specifications:
47
* Frame: 25mm square metal tubing, bolted to the wall.
48
* Vertical Bars: 16mm round, 120mm c/c.
49
* Centre Horizontal Bar: 30mm x 5mm flat bar.
50
</p>
51
52
<p>While the above may be used as a guide, the diameter and the
53
finish of the bars can be further determined by the school
54
authorities and the project manager, as is deemed necessary
55
according to the known risk in the area.
56
_________________________________________________________
57
</p>
58
59
<p>5.1.2. Stone guards
60
</p>
61
62
<p>Galvanised metal mesh should be fitted on all outside windows.
63
</p>
64
65
<p>The sides of the frame should be closed. For fasteners, use
8
9
<p>
10
Before you carry a lot of computers into a room, there needs to be a
11
good deal of preparation. A classroom will need to be modified to
12
include special features, such as a lockable cabinet to secure the
13
switch and server, and a layout that accommodates the re-arrangement,
14
addition, or removal of furniture. Electricity is another
15
consideration: every computer needs power, and in order to protect
16
them from power surges, the computers need to be on a separate power
17
circuit.
18
</p>
19
<p>
20
Security is also an important consideration, and will involve at least
21
burglar bars on the windows and an alarm system. The exact security
22
measures that should be taken will differ from school to school.
23
Several factors should be considered: for example, the known crime
24
rate in the area, the isolation of the school, and the affordability
25
of the security measures.
26
</p>
27
28
<p><img src="illustrations/lablayout.png" /></p>
29
30
<h2>Security [6]</h2>
31
32
<p>
33
Here are some guidelines to consider when selecting a room for an
34
Edubuntu lab. They aren't hard and fast rules, and when you look
35
through them, you'll notice where there's room for initiative. They
36
should however be taken as a baseline to improve upon where there's
37
opportunity.
38
</p>
39
40
<h3>Window security</h3>
41
42
<p>Specifications:</p>
43
<ul>
44
<li>Frame: 25mm square metal tubing, bolted to the wall.</li>
45
<li>Vertical Bars: 16mm round, 120mm c/c.</li>
46
<li>Centre Horizontal Bar: 30mm x 5mm flat bar.</li>
47
</ul>
48
49
<p>
50
While the above may be used as a guide, the diameter and the finish of
51
the bars can be further determined by the school authorities and the
52
project manager, as is deemed necessary according to the known risk in
53
the area.
54
</p>
55
56
<h3>Stone guards</h3>
57
58
<p>
59
Galvanised metal mesh should be fitted on all outside windows.
60
</p>
61
62
<p>
63
The sides of the frame should be closed. For fasteners, use
66
64
tamperproof coach screws with turn-off heads.
67
65
</p>
68
66
69
<p><img src="illustrations/coach-screw.png">
67
<p>
68
<img src="illustrations/coach-screw.png" />
70
69
A coach screw. Note the double head. The top part turns off,
71
70
making the screw very hard to remove once it's in.
72
_________________________________________________________
73
</p>
74
75
<p>5.1.3. Non-concrete ceiling security
76
</p>
77
78
<p>Wherever possible, the room identified for the lab should have
79
a concrete floor above it. This means that in schools with two
80
levels, it is preferable to select a room on the lower level.
81
Where this is not possible and the ceiling is of hardboard or
82
something equally flimsy, the ceiling should be covered with
83
wire mesh or razor wire. In order to notice tampering, it's
84
probably best for the wire to be beneath the ceiling.
85
_________________________________________________________
86
</p>
87
88
<p>5.1.4. Door security
89
</p>
90
91
<p>Since the gate is the key security feature, it should be made
92
of steel of substantial thickness. In some cases, an internal
93
security cage with steel gate or double steel gates are
94
advised, depending on finances and risks. Methods of securing
95
and fitting of locks should be strategic to make breaking in
96
as difficult as possible.
97
</p>
98
99
<p>Specifications:
100
</p>
101
102
<p>* Frame: 50mm x 50mm x 5mm. Angle Iron bolted to the wall on
103
3 sides.
104
<img src="illustrations/angleironbracket.png">
105
Angle iron and bracket
106
* Bolts should be welded shut, or tamperproof.
107
* The fitting of two barrel type locks covered with metal
108
plates is advised.
109
<img src="illustrations/barreltypelock.png">
110
_________________________________________________________
111
</p>
112
113
<p>5.1.5. Alarm system
114
</p>
115
116
<p>A security alarm system with at least two room sensors is
117
required. If the lab has a ceiling, a sensor in the ceiling is
118
advised. The alarm must be monitored around the clock, with
119
armed response in the event of an alarm event.
120
</p>
121
122
<p>The number and location of sensors should be determined with
123
input from security companies.
124
_________________________________________________________
125
</p>
126
127
<p>5.2. Infrastructure
128
</p>
129
130
<p>5.2.1. Specifications for desktops
131
</p>
132
133
<p>The design and length of desktops in most cases is determined
134
by the number of computers and learners, and the size of the
135
room. If there is room, it's advisable to install desktops for
136
future expansion of computer network at once, depending on the
137
finances available.
138
</p>
139
140
<p>New desktops should be postform, minimum 28mm thick or similar
141
stock, with a melamine/Formica/varnished finish. They must be
142
900mm deep, to accommodate the keyboard, screen, and cabling
143
without crowding and with proper ventilation. Depending on the
144
chair height and the age of the learners, the top of the
145
desktops should be 700 to 720mm from the floor. It is
146
important for the desks to be at an appropriate height for the
147
learners who will be using the lab, as an awkward posture can
71
</p>
72
73
<h3>Non-concrete ceiling security</h3>
74
75
<p>
76
Wherever possible, the room identified for the lab should have a
77
concrete floor above it. This means that in schools with two levels,
78
it is preferable to select a room on the lower level. Where this is
79
not possible and the ceiling is of hardboard or something equally
80
flimsy, the ceiling should be covered with wire mesh or razor wire. In
81
order to notice tampering, it's probably best for the wire to be
82
beneath the ceiling.
83
</p>
84
85
<h3>Door security</h3>
86
87
<p>
88
Since the gate is the key security feature, it should be made of steel
89
of substantial thickness. In some cases, an internal security cage
90
with steel gate or double steel gates are advised, depending on
91
finances and risks. Methods of securing and fitting of locks should be
92
strategic to make breaking in as difficult as possible.
93
</p>
94
95
<p>Specifications:</p>
96
97
<ul>
98
<li>Frame: 50mm x 50mm x 5mm. Angle Iron bolted to the wall on
99
3 sides.</li>
100
</ul>
101
<p><img src="illustrations/angleironbracket.png" />
102
Angle iron and bracket</p>
103
<ul>
104
<li>Bolts should be welded shut, or tamperproof.</li>
105
<li>The fitting of two barrel type locks covered with metal
106
plates is advised.</li>
107
</ul>
108
<p><img src="illustrations/barreltypelock.png" /></p>
109
110
<h3>Alarm system</h3>
111
112
<p>
113
A security alarm system with at least two room sensors is required. If
114
the lab has a ceiling, a sensor in the ceiling is advised. The alarm
115
must be monitored around the clock, with armed response in the event
116
of an alarm event.
117
</p>
118
<p>
119
The number and location of sensors should be determined with input
120
from security companies.
121
</p>
122
123
<h2>5.2. Infrastructure</h2>
124
125
<h3>Specifications for desktops</h3>
126
127
<p>
128
The design and length of desktops in most cases is determined by the
129
number of computers and learners, and the size of the room. If there
130
is room, it's advisable to install desktops for future expansion of
131
computer network at once, depending on the finances available.
132
</p>
133
134
<p>
135
New desktops should be postform, minimum 28mm thick or similar stock,
136
with a melamine/Formica/varnished finish. They must be 900mm deep, to
137
accommodate the keyboard, screen, and cabling without crowding and
138
with proper ventilation. Depending on the chair height and the age of
139
the learners, the top of the desktops should be 700 to 720mm from the
140
floor. It is important for the desks to be at an appropriate height
141
for the learners who will be using the lab, as an awkward posture can
148
142
impair concentration.
149
143
</p>
150
144
151
<p><img src="illustrations/gat-v-draad.png">
152
For every workstation, the desktops have a hole that collects
153
and passes through the network and power cables to the
154
trunking under the desks.
155
_________________________________________________________
156
</p>
157
158
<p>5.2.2. Wall brackets and centre aisle framework
159
</p>
160
161
<p>Desktops should be mounted on 40mm x 40mm x 5mm angle iron
162
brackets. They should only have legs if brackets are not a
163
option, as legs tend to get in the way of learners sharing
164
workstations. Each bracket must be a minimum of 750mm x 650mm.
165
The brackets must be no less than 1000mm apart and each must
166
be fixed with at two heavy duty rawlbolts, one of which must
167
be as high up as possible.
168
</p>
169
170
<p>Where appropriate, provision should be made for ducting along
171
which to run wiring and network cabling underneath the work
172
surfaces, with holes in the desktops to allow the cables to
173
reach the computers and peripherals.
174
</p>
175
176
<p>Where possible, the length of the desk should be chosen to
177
allow 1200mm of space for each computer.
178
_________________________________________________________
179
</p>
180
181
<p>5.2.3. Specification for server cabinet
182
</p>
183
184
<p>If it's at all possible, put the server in a separate room,
185
where it's out of sight and locked away permanently. All that
186
is necessary is for a network fly-lead to reach from the
187
server to the network switch. Otherwise, a well ventilated,
188
lockable cabinet should be built.
189
</p>
190
191
<p>This cabinet should be at least 900mm square inside, as it
192
will house the classroom server, another server acting as
193
internet gateway, and a modem. The cabinet will be set away
194
from the wall to allow for ventilation, since a pair of
195
servers will generate a good deal of heat.
196
</p>
197
198
<p>Note
199
</p>
200
201
<p>* A wall mounted steel mesh cabinet can also be installed.
202
* Dimensions for steel mesh cage: LxDxH: 1200mm x 750mm x
203
720mm.
204
* Height: 720mm Includes a 32mm x 900mm Postform Top.
205
* Doors: 2 doors 450mm wide is required on the 900mm
206
section.
207
* Suitable locks must be fitted so that the doors cannot be
208
easily opened.
209
_________________________________________________________
210
</p>
211
212
<p>5.3. Electrical requirements
213
</p>
214
215
<p>5.3.1. Specification of electrical wall points
216
</p>
217
218
<p>It's important that all electrical work be done by a qualified
219
technician, who should issue a certificate of compliance to
220
the school upon completion of the work.
221
</p>
222
223
<p>There must be enough 15 amp 3-point plugs to accommodate each
224
computer on a separate plug, and in addition, there should be
225
enough plugs for peripherals as well. A good rule of thumb is
226
to have a double plug for each computer point. For safety
227
reasons, electrical wiring must be in conduit piping below the
228
work surfaces, but Surfix-type cable and wall mounted sockets
229
are also acceptable and should be installed below desktops.
230
</p>
231
232
<p><img src="illustrations/surfixcable.gif">
233
This is a cross section of a Surfix cable.
234
</p>
235
236
<p><img src="illustrations/wallsocket.gif">
237
</p>
238
239
<p>To avoid power spikes and dips, which are extremely damaging
240
to workstations, the computer lab must be on its own
241
electrical circuit. The circuit must be broken into segments,
242
each adequate to accommodate the computers and peripherals on
243
that segment. Air conditioners, or other equipment that use a
244
lot of electricity, must not share the circuit with the
245
computers.
246
</p>
247
248
<p><img src="illustrations/onwettige-plug.png">
249
Don't use extension leads or multi-plugs. They can cause
250
shorts and power spikes that may damage your equipment.
251
</p>
252
253
<p>Electrical wires to an island worktop in the middle of the
254
room must preferably be under the floor or must have suitable
255
ducting. Otherwise, it is a perfect certainty that someone
256
will fall over the wires, breaking their neck and bringing all
257
the workstations within reach crashing to the floor.
258
_________________________________________________________
259
</p>
260
261
<p>5.3.2. Sub-distribution electrical board
262
</p>
263
264
<p>The sub-distribution board should be fitted with earth leakage
265
protection, if required. A maximum of five wall plug sockets
266
should be connected to one circuit, and each circuit should be
267
protected by a 20 amp circuit breaker.
268
_________________________________________________________
269
</p>
270
271
<p>5.4. Network infrastructure
272
</p>
273
274
<p>5.4.1. Switch cabinet
275
</p>
276
277
<p>Where required, a 4U cabinet will be installed to house a
278
minimum of two 24-port switches [7], leaving some space for
279
expansion. Server equipment is a bit like bricks: they're all
280
the same basic shape. One switch is 1U (or unit) big, so a 4U
281
cabinet has room for four of them. Computer suppliers will
282
know what you're talking about.
283
</p>
284
285
<p>The placing of the switch cabinet should determined by the lab
286
layout, and to minimise the required cable lengths, it should
287
be placed in a central position. If installed in the lab, the
288
cabinet should be 1000mm above or below desktops.
289
</p>
290
291
<p><img src="illustrations/switch.gif">
292
Cabinet to house switches
293
_________________________________________________________
294
</p>
295
296
<p>5.4.2. Network trunking
297
</p>
298
299
<p>Network cabling must run in 40mm x 40mm square trunking. If
300
financial considerations require that network cabling share
301
the trunking of the electrical cabling, it is imperative for
302
the electricity to be switched off at the sub-distribution
303
board whenever the trunking is opened during network
304
troubleshooting.
305
</p>
306
307
<p><img src="illustrations/trunking.gif">
308
Trunking running under the desks.
309
</p>
310
311
<p>Ensure that 10mm holes are made in trunking for the cable ends
312
to reach their workstations. Allow at least 500mm of free
313
network cable per computer, and loop and tie the extra length
314
neatly. Network cables that are too short can be just as
315
irritating as socks that are two sizes too small, and moreover
316
lead to high blood pressure and increased risk of cardiac
317
arrest. Cabling to an island desktop must preferably be under
318
the floor or must have suitable ducting that will ensure the
319
safety of pupils who have to walk over these cables.
320
_________________________________________________________
145
<p>
146
<img src="illustrations/gat-v-draad.png" /> For every workstation, the
147
desktops have a hole that collects and passes through the network and
148
power cables to the trunking under the desks.
149
</p>
150
151
<h3>Wall brackets and centre aisle framework</h3>
152
153
<p>
154
Desktops should be mounted on 40mm x 40mm x 5mm angle iron
155
brackets. They should only have legs if brackets are not a option, as
156
legs tend to get in the way of learners sharing workstations. Each
157
bracket must be a minimum of 750mm x 650mm. The brackets must be no
158
less than 1000mm apart and each must be fixed with at two heavy duty
159
rawlbolts, one of which must be as high up as possible.
160
</p>
161
162
<p>
163
Where appropriate, provision should be made for ducting along which to
164
run wiring and network cabling underneath the work surfaces, with
165
holes in the desktops to allow the cables to reach the computers and
166
peripherals.
167
</p>
168
169
<p>
170
Where possible, the length of the desk should be chosen to allow
171
1200mm of space for each computer.
172
</p>
173
174
<h3>Specification for server cabinet</h3>
175
176
<p>
177
If it's at all possible, put the server in a separate room, where it's
178
out of sight and locked away permanently. All that is necessary is for
179
a network fly-lead to reach from the server to the network
180
switch. Otherwise, a well ventilated, lockable cabinet should be
181
built.
182
</p>
183
184
<p>
185
This cabinet should be at least 900mm square inside, as it will house
186
the classroom server, another server acting as internet gateway, and a
187
modem. The cabinet will be set away from the wall to allow for
188
ventilation, since a pair of servers will generate a good deal of
189
heat.
190
</p>
191
192
<p>Note</p>
193
194
<ul>
195
<li>A wall mounted steel mesh cabinet can also be installed.</li>
196
<li>Dimensions for steel mesh cage: LxDxH: 1200mm x 750mm x 720mm.</li>
197
<li>Height: 720mm Includes a 32mm x 900mm Postform Top.</li>
198
<li>Doors: 2 doors 450mm wide is required on the 900mm section.</li>
199
<li>Suitable locks must be fitted so that the doors cannot be easily opened.</li>
200
</ul>
201
202
<h2>Electrical requirements</h2>
203
204
<h3>Specification of electrical wall points</h3>
205
206
<p>
207
It's important that all electrical work be done by a qualified
208
technician, who should issue a certificate of compliance to the school
209
upon completion of the work.
210
</p>
211
<p>
212
There must be enough 15 amp 3-point plugs to accommodate each computer
213
on a separate plug, and in addition, there should be enough plugs for
214
peripherals as well. A good rule of thumb is to have a double plug for
215
each computer point. For safety reasons, electrical wiring must be in
216
conduit piping below the work surfaces, but Surfix-type cable and wall
217
mounted sockets are also acceptable and should be installed below
218
desktops.
219
</p>
220
221
<p>
222
<img src="illustrations/surfixcable.gif" /> This is a cross section of
223
a Surfix cable.
224
</p>
225
226
<p><img src="illustrations/wallsocket.gif" /></p>
227
228
<p>
229
To avoid power spikes and dips, which are extremely damaging to
230
workstations, the computer lab must be on its own electrical
231
circuit. The circuit must be broken into segments, each adequate to
232
accommodate the computers and peripherals on that segment. Air
233
conditioners, or other equipment that use a lot of electricity, must
234
not share the circuit with the computers.
235
</p>
236
237
<p>
238
<img src="illustrations/onwettige-plug.png" /> Don't use extension
239
leads or multi-plugs. They can cause shorts and power spikes that may
240
damage your equipment.
241
</p>
242
243
<p>
244
Electrical wires to an island worktop in the middle of the room must
245
preferably be under the floor or must have suitable ducting. Otherwise,
246
it is a perfect certainty that someone will fall over the wires,
247
breaking their neck and bringing all the workstations within reach
248
crashing to the floor.
249
</p>
250
251
<h3>Sub-distribution electrical board</h3>
252
253
<p>
254
The sub-distribution board should be fitted with earth leakage
255
protection, if required. A maximum of five wall plug sockets should be
256
connected to one circuit, and each circuit should be protected by a 20
257
amp circuit breaker.
258
</p>
259
260
<h2>Network infrastructure</h2>
261
262
<h3>Switch cabinet</h3>
263
264
<p>
265
Where required, a 4U cabinet will be installed to house a minimum of
266
two 24-port switches [7], leaving some space for expansion. Server
267
equipment is a bit like bricks: they're all the same basic shape. One
268
switch is 1U (or unit) big, so a 4U cabinet has room for four of
269
them. Computer suppliers will know what you're talking about.
270
</p>
271
272
<p>
273
The placing of the switch cabinet should determined by the lab layout,
274
and to minimise the required cable lengths, it should be placed in a
275
central position. If installed in the lab, the cabinet should be
276
1000mm above or below desktops.
277
</p>
278
279
<p><img src="illustrations/switch.gif" /> Cabinet to house switches</p>
280
281
<h3>Network trunking</h3>
282
283
<p>
284
Network cabling must run in 40mm x 40mm square trunking. If financial
285
considerations require that network cabling share the trunking of the
286
electrical cabling, it is imperative for the electricity to be
287
switched off at the sub-distribution board whenever the trunking is
288
opened during network troubleshooting.
289
</p>
290
291
<p><img src="illustrations/trunking.gif" /> Trunking running under the
292
desks.</p>
293
294
<p>
295
Ensure that 10mm holes are made in trunking for the cable ends to
296
reach their workstations. Allow at least 500mm of free network cable
297
per computer, and loop and tie the extra length neatly. Network cables
298
that are too short can be just as irritating as socks that are two
299
sizes too small, and moreover lead to high blood pressure and
300
increased risk of cardiac arrest. Cabling to an island desktop must
301
preferably be under the floor or must have suitable ducting that will
302
ensure the safety of pupils who have to walk over these cables.
303
</p>
321
304
322
305
</body>
323
306
</html>
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