We are making miles and miles of progress toward the metric system Gerald Ford

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We are makingmiles and milesof progress toward
the metric systemGerald Ford
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Its fun to kid about the metric system,
but.this presentation will show that the
President was right!
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CONSTRUCTIONMETRICATION
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Produced by theConstruction Metrication
Councilof the National Institute ofBuilding
Sciences,Washington, D.C.October 2002
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To begin at thebeginning..
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Thomas Jefferson was intrigued by the metric
system and strongly advocated the use of
decimal-based measuresBut he only got half of
whathe wanted...
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METRIC MONEY That is, money based on the
decimal system
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.and metricstock prices, too That is,
decimal-basedstock prices
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BUT we insist on keeping the archaicinch-poundm
easurement system based on...
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fractions of an inch...12 inches to a foot.3
feet to a yard. 5.5 yards to a rod...320 rods
to a mile... 43,560 sq ft to an acre...
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16 ounces to a pound...(avoirdupois)12 ounces
to a pound...(troy)4 quarts to a gallon...3
teaspoons to a tablespoon
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You get the point
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While the U.S. continues usinginch-poundmeasures
,the other 94 of the worldhas adopted
theMETRIC SYSTEM
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Now the metric system(Standard International or
SI)is all around us
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We buy cola in liters...We by film in
millimeters...We run 10 km races...(in fact,
all U.S. track andfield events are in metric
units)We swim in 25 meter pools...We watch
metric Olympics...
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The entire U.S. automobile industry is
metric...All pharmaceuticals are metric...as is
the entire health care industry
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Also metricThe liquor industry Most farm
machinery and heavy equipmentThe machine tool
industry Most electronics All medicine and
science
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And guess what?We think nothing of it!
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So whats left?
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Baseball and football(some things are
sacred)Plus everyday consumer goods and
measurements --and until recently...
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ConstructionBut thats changing,too
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Overseas,U.S. architects, engineers, and
contractors do over100 BILLION in metric
workevery year
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Guess what again?Its not a problemEveryone
easily adapts to metric usage -- then the
prefer it
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Our Canadian and Mexican neighbors also buildin
metric unitsCanada and Mexico account forabout
70 of all U.S. exports
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Now, U.S. federally-fundedconstructionis being
built inmetric measures, too
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Federal-fundedmetric construction is1O-15
BILLIONannually
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With so muchcivil engineeringin metric units,
some state and local governments are alsogoing
metric
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Almost without notice,the metric system is
burrowing in inthe U.S. constructionindustry
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No one knows how long it will take to metricate
ALL construction, but it easily could be done
withinTEN YEARS
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Regardless of how long,metrication is
inevitableits just a question ofnow or
later Why not now, so wecan reap the benefits
sooner?
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FACTS ABOUTCONSTRUCTIONMETRICATION
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FACT Metrication is largely a paper change and
the paper change is largely complete
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FACT The model codes and most construction
standards contain metric units, as do all federal
and state highway standards, criteria, and
specifications
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FACTContractors and the trades adapt readily to
metric usageif they have adequate timeon the
job to learn it
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FACT Work is still donethe same wayby the
same peoplewith the same skills...
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and with the same experience,using the same
products,and almost all ofthe same tools and
equipment
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FACTThe costs of metric projects consistently
have been comparable to conventionalinch-pound
projects...
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METRICDOESNTCOST MORE.on large jobs!
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Metric-related problemshave been FEWSchedules
have beenUNAFFECTED
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FACTLittle metric trainingis needed for most
crafts
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Almost all trainingcan be performedon-the-job
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THEBENEFITS
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BENEFITMetrication can increase
constructionsEFFICIENCY AND QUALITY
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...making us morecost-effectiveat home and
atougher competitorabroad
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The simplicity of adecimal-based systemspeeds
workand reduces errors
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BENEFIT Metrication willexpand export
opportunities forU.S. building products
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...and for even moreU.S. architectural,engineeri
ng, andconstruction services
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because we finallywill be usingthe same
measurement systemas the rest of the world
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BENEFIT Metrication will bring6 million U.S.
workers and13 of our GDPinto the world
standard of measurement to...
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BENEFITALLAMERICANS
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WHAT WILL CHANGEANDWHAT WILL STAYTHE SAME
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METRICMODULE
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What will changeThe basic building
module,from 4 inchesto 100 mm
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What will stay the sameA module based on
rational, easy-to-use dimensionsThe 100 mm
module is theworld standard
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DRAWINGS
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What will changeFeet and inches to
millimetersfor building dimensionsand meters
forsite plans and civil drawings
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Unit notations areunnecessaryif theres no
decimal point,its millimetersif theres a
decimal pointcarried to one, two or three
places, its meters
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A millimeter is quite small(exactly 1/25.4 of an
inch)but it works surprising wellon drawings
and in the field
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In accordance with ASTM E621, CENTIMETERS are not
used inconstruction because1) They are not
consistent with the preferred use of multiples of
1000(that is, tertiary powers of 10)
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2) The order of magnitude between a millimeter
and a centimeter is only 10 the use of both
leads to confusion and requires the use of unit
symbols on drawings3) The use of millimeters
almost entirely eliminates decimal fractions
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NEVER use both inch-pound andmetric units on a
drawing!Using dual units--Increases
dimensioning time--Doubles the chance for
errors--Makes drawing more confusing--Postpones
the learning process
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If you MUST includeinch-pound units,forget
metricationand use inch-pound units onlyWith
dual units, no one uses the metric units anyway
and they just clutter up the drawings and add
confusion
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DRAWINGSCALES
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What will changeInch-fraction scales will
change to true ratio scales150 (close to 1/4
1-0)1100 (close to 1/8 1-0)1200 (close
to 1/16 1-0)1500 (close to 1 40-0)
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Inch-fraction scales can beconverted to true
ratio scales by multiplying the scales
divisorby 12 (inches)For example, for 1/4
1-0,multiply the divisor, 4, by 12 for a
trueratio of 148 this is very close to the
metric scale of 150
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DRAWINGSIZES
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What will changeDrawing sizes,to ISO A
seriesA0 1189 x 841 mm (46.8 x 33.1 in)A1
841 x 594 mm (33.1 x 23.4 in)A2 594 x 420 mm
(23.4 x 16.5 in)A3 420 x 297 mm (16.5 x 11.7
in)A4 297 x 210 mm (11.7 x 8.3 in)
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Of course,metric drawings can bemade on any
sizepaper
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CONSTRUCTIONPRODUCTSIN GENERAL
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What will changeA few modular products,such
as concrete block,drywall, plywood, suspended
ceilings, and raised floors...
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plusproducts that are fabricated or formed for
each job, such as cabinets, wood trusses,
ductwork, commercial doors and windows, and
concrete work
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Such products usually can be made in inch-pound
or metric sizes with equal ease
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What will stay the sameAll other products,
since they are cut-to-fit,likeframing
materials, structural steel, wood trim, siding,
wiring,piping, and roofing...
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or their placement isnot dimensionally
sensitive,likefasteners, hardware, electrical
components, plumbing fixtures, and HVAC equipment
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Such products simply will be relabeled in metric
units
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Eventually, manufacturers may convert the
physical dimensions of many of these products to
new rational metric sizes
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2 X 4SAND OTHER 2-BYWOOD AND METAL FRAMING
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What will changeSpacing ,from 16 to 400
mmand from 24 to 600 mm
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Metric-spaced framing members are placed slightly
closer together than normal, since400 mm
15.7600 mm 23.6
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What will stay the sameEverything else2x4s
will not change size
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Since 2-bys are made in odd, fractional inch
sizes,there is no need to changethem to new,
roundedmetric sizes
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2 x 4s probably will keep their names
forever...unless they someday areresized to
new, rounded metric dimensions-- then theyll
get metric names
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DRYWALL,PLYWOOD, OSB, PARTICLE BOARD, AND
RELATED SHEET PRODUCTS
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What will changeWidths, from 4-0 to 1200
mmHeights, from 8-0 to 2400 mmand from
10-0 to 3000 mm
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What will stay the sameThicknesses,so fire,
acoustic, andthermal ratings wont haveto be
recalculated
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Metric drywall and plywood are readily
availablebut may require longerdelivery times
and maycost more in small amountsuntil their
use becomesmore common
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BATTINSULATION
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What will changeNothing,although batts may be
relabeled to include nominalmetric widths, such
as16/400 mm or24/600 mm
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Batts wont change in width or thickness
--theyll just have a little tighterfriction
fit when installed between metric-spacedframing
members
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DOORS
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What will changeDoor heights,from 6-8
(80)to 2050 mm (80.7)or 2100 mm (82.6)
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Door widths, from30 to 750 mm (29.5)32 to
800 mm (31.5)34 to 850 mm (33.5)36 to 900
mm (35.4)40 to 1000 mm (39.4)
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What will stay the sameDoor thicknesses and
hardwareFor commercial work,doors and windows
can be ordered in any size since they ordinarily
arecustom made for the job
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That said,conventional inch-pound doors can be
used in many metric wallapplications(such as
drywall partitions)with equal ease
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SUSPENDEDCEILINGSYSTEMS
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What will changeGrid spacing, lay-in ceiling
tile,air diffusers, and recessed lighting
fixtures (troffers)...
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from24 x 24 to 600 x 600 mm(23.6 x
23.6)and from24 x 48 to 600 x 1200 mm(23.6
x 47.2)
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What will stay the sameGrid profiles, tile
thicknesses, air diffuser capacities, fluorescent
tubes, and means of suspension
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Note The Cox Bill (P.L. 104-289) prohibits
federal contract documents from solely specifying
metric recessed lighting fixturesThe layout and
specification of metric fixtures and ceiling
systems may continue but specifications must
allow contractors to substituteinch-pound
components
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The use of metric recessed fixturesmay present
installation problemssince they cannot be
placedend-to-end or end-to-wall
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In such cases,other types of lighting(can,
pendant, wall, task, floor) should be
substitutedorthe ceiling system and its
fixturesshould be specified inconventional
inch-pound sizes
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RAISEDFLOORSYSTEMS
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What will changeGrid spacing and lay-infloor
tiles and carpet squares,from 24 x 24to 600 x
600 mm
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What will stay the sameGrid profiles, floor
tile thicknesses, and means of support
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BRICK
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What will changeMortar joints, from3/8 to 10
mmThe brick module, from24 x 24 to 600 x 600
mm
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What will stay the sameStandard brick sizes
and everyday masonry practicesOf the 100 or so
brick sizes commonly made, almost all are within
a millimeter or soof a metric brick size
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CONCRETEBLOCK
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What will changeBlock sizes, from a7-5/8 x
15-5/8 face to190 x 390 mm(7-1/2 x
15-3/8)Notice that conventional block is 1/8
taller and 1/4 longer than metric block
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Mortar joints will also change, from 3/8 to 10
mm(3/8 9.5 mm)
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What will stay the sameEveryday masonry
practices
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Note The Cox Bill (P.L. 104-289) prohibits
federal contract documents from solely specifying
metric blockThe layout and specification
ofblock walls may continue but specifications
must allow contractors to substitute inch-pound
block
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Whenever possible, block wallsshould be
designedin a manner that permitsthe use of
either inch-poundor metric block
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This is usually easy to do forinfill and backup
block wallsbut it may be difficult forblock
bearing walls,since metric blocks
slightlysmaller size affects coursing
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PIPE
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What will changeNominal pipe designations,
from inches to millimeters1/2 15 mm3/4 20
mm1 25 mm1-1/2 40 mm2 50 mm
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What will stay the samePipe diameters and
threadsLike 2 x 4s , pipe is made in odd,
fractional inch sizes,so there is no need to
changepipe to new, rounded metric sizes
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STRUCTURALSTEEL
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What will changeDesignations,from inches to
millimetersand from pounds per foot tokilograms
per meterper ASTM A6M
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Structural steel bolts,to metric diameters and
threadsper ASTM A325 M and A490M
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What will stay the sameCross sectional
sizesLike 2 x 4s and pipe,structural steel is
rolled primarily in odd, fractional inch sizes,
so there is no need to change structural steel to
new,rounded metric sizes
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CONCRETE
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What will changeStrength designations,
frompsi to megapascalsper ACI 318M2500 psi
to 20 MPa3000 psi to 25 MPa4000 psi to 30 MPa
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What will stay the sameEverything
elseconcrete conforms to thesize and shape of
itsformwork
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REBAR
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What will changeConcrete reinforcing baris
being renamed inmetric unitsper ASTM
A615M-96aand ASTM A706-96a
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...as followsNo. 3 to No. 10No. 4 to No.
13No. 5 to No. 16No. 6 to No. 19No. 8 to No. 22
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What will stay the sameActual rebar sizes
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ELECTRICALWIRE
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What will changeNothing at this time
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What will stay the sameExisting American
WireGage (AWG) sizes
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READINGMETRICDRAWINGS
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Reading metric drawingsrequires visualizing
dimensions in metric unitsThis takes practice
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Meanwhile,a few rules-of-thumbcan help you
tovisualize metric dimensionseasily
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Rules of thumb25 mm about 1 inch300 mm
about 1 foot
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1 m (1000 mm) about 3 ft 10 more3 m
about 10 ft(9.84 ft)
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1 square meter about 10 square feet(10.76 sq
ft)
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Review25 mm 1 inch300 mm 1 foot1000 mm
1 m 3 feet 10 more1 square meter 10
square feet
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PROBLEMA rooms dimensions areshown as 3 000 x
4 500 What size is the roomin feet?
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Using 1000 mm 1 m about 3 feet 10 more
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3 m x 3 9 ft 10 (0.9) about 10 ft(actual
9.8 ft)4.5 m x 3 13.5 ft 10 (1.3)
about 15 ft(actual 14.8 ft)
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...or, using300 mm about 1 foot3 000/300
30/3 about 10 ft4 500/300 45/3 about 15 ft
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PROBLEMA building is 4500square meters in
areaHow big is it in square feet?
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Using 1 square meter about 10 square
feet4500 x 10 about 45 000 sq ft(actual
48,450 sq ft)
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PROBLEMA gypsum wall assemblyis 125
thickWhat is its thickness in inches?
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Using 25 mm 1 inch125/25 5 inches
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PROBLEMA water supply line is labeled50What
size is the pipe ininch-pound units?
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Using metric pipe designationswhere 1 25
mm50/25 2-inch pipe
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PROBLEMA steel lintel is labeled90 x 90 x
6What is its size in inches?
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90/25 3-1/2 inches6/25 1/4 inchThe lintel
is3-1/2 x 3-1/2 x 1/4
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Not so hard, is it?
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So.GO METRIC!