A Guide to Radio

Frequency Hazards

with Electric Detonators

J. Hugh Strong, James H. Turner,and Michael W. Wortham

Sydney Cheryl SuttonEditor

N.C. Department of LaborDivision of Occupational Safety and Health

4 W. Edenton St.Raleigh, NC 27601-1092

Cherie K. BerryCommissioner of Labor

N.C. Department of LaborOccupational Safety and Health Program

Cherie K. BerryCommissioner of Labor

OSHA State Plan Designee

To obtain additional copies of this book, or if you havequestions about N.C. occupational safety and healthstandards or rules, please contact:

N.C. Department of LaborBureau of Education, Training and Technical Assistance

4 W. Edenton St.Raleigh, NC 27601-1092

Phone: (919) 807-2875 or 1-800-NC-LABOR____________________

Additional sources of information are listed on theinside back cover of this book.

____________________The projected cost of the OSHNC program for federal fiscal year 2002–2003is $13,130,589. Federal funding provides approximately 37 percent($4,920,000) of this total.Printed 3/98, 2M

Acknowledgments

A Guide to Radio Frequency Hazards withElectric Detonators was prepared for the NorthCarolina Department of Labor by the Mine andQuarry Bureau of the North Carolina Departmentof Labor. The Mine and Quarry Bureau gratefullyacknowledges the cooperation of the Institute ofMakers of Explosives (IME), Washington, D.C., inthe preparation of this guide. All of the tables inpart 2 of this guide were taken from IME SafetyLibrary Publication No. 20.

ContentsPart Page

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1iiv

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1ivi

1 Electric Detonators and Hazards Posedby Radio Frequency Energy . . . . . . . . . . . . . . .1ii1Initiation of Electric Detonatorsby Radio Frequency Energy . . . . . . . . . . . .1ii1

Radio Frequency Energy Sources . . . . . . .1ii2Radio Frequency Pickup Circuits. . . . . . . .1ii8General Precautions against RFEnergy Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . ii12

Transportation of Electric Detonators . . . ii13Citizens Band Transmitters andCellular Telephones. . . . . . . . . . . . . . . . . . . . . . ii14

2 Tables of Distances—RF Sources andElectric Detonators . . . . . . . . . . . . . . . . . . . . . . . . . ii15I. Recommended Distances for Commercial

AM Broadcast Transmitters . . . . . . . . . ii15II. Recommended Distances for

Transmitters up to 50 MHz . . . . . . . . . . ii16III. Recommended Distances for VHF TV

FM Broadcasting Transmitters . . . . . . ii16IV. Recommended Distances for UHF TV

Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . ii17V. Radio Transmitting Stations . . . . . . . . . . ii18

VI. Recommended Distances of MobileTransmitters Including Amateurand Citizens Band. . . . . . . . . . . . . . . . . . . . . ii20

iii

Appendix—Standards and Regulationsfor the Use of Electric Detonators aroundRadio Frequency Hazards . . . . . . . . . . . . . . . . . ii22

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii26

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii28

iv

ForewordThe Mine and Quarry Bureau of the North Carolina

Department of Labor prevents work-related injuriesand illnesses by offering training in the safe use ofexplosives and blasting devices. A Guide to RadioFrequency Hazards with Electric Detonators contributesto that objective. It describes hazards of radio frequencyenergy to the loading and firing of electrically initiatedblasting operations and sets forth precautions thatshould be taken during such operations. Many of thesehazards are covered by the state’s Occupational Safetyand Health Division’s (OSHNC) standards.

In this state, the North Carolina Department ofLabor consultants and inspectors administer the federalOSHA laws through a plan approved by the U.S.Department of Labor. All current OSHA standards areenforced. Many educational programs, publications(including this guide), and other services are alsooffered to help inform people about their rights andresponsibilities regarding OSHA.

As you look through this guide, please remember thatOSHA’s mission is greater than just enforcement. Anequally important goal is to help citizens find ways tocreate safe and healthy workplaces. Reading and usingthe information in this booklet, like other educationalmaterials produced by the North Carolina Departmentof Labor, can help.

Cherie K. BerryCommissioner of Labor

v

vi

IntroductionThe purpose of this guide is to promote safe work

practices by assisting persons who use electric detona-tors in assessing hazards of the initiation of commercialelectric detonators by radio frequency (RF) energy. Thisguide also provides tables of safe distances from RFsources for the use of electric detonators.

Part 1 identifies major RF sources. Part 2 offerstables for safe distances between particular RF sourcesand the use of electric detonators. Adherence to thetables in part 2 provides the user of electric detonatorsa high degree of assurance that the blasting layoutshould be safe from RF initiation.

This guide applies to commercial electric detonators.It does not apply to military electric firing devices. lt isrecommended that, prior to market introduction, anyimported electric detonators be tested for safety proper-ties by an authorized United States laboratory, such asthe U.S. Bureau of Mines or Bureau of Explosives.

Information in this guide derives from sources reflect-ing competent analysis and research and is believed to beaccurate. Nevertheless, the reader cannot be guaranteedthat the guide will apply to every application or variationin the use of electric detonators. The references section ofthis guide includes additional sources of information forunusual situations in which electric detonators are used.

The information contained in this guide is basedupon many years of practical experience and the latestand most widely accepted publications available in thefield. As such, it is believed that all data presented areboth accurate and reliable. However, the NorthCarolina Department of Labor makes no warranties,expressed or implied, to the user of this publication.All risks associated with the use of the informationare assumed by the user, and the North Carolina

Department of Labor hereby expressly denies any andall liability for use of this information. This publicationis not to be taken as a license to operate or recommen-dation to infringe any patent.

Though this guide is not intended to be incon-sistent with OSH or MSHA standards, if an area isconsidered by the reader to be inconsistent, thestandard should be followed.

vii

1Electric Detonators andHazards Posed by Radio

Frequency EnergyThe normal method of firing an electric detonator is

to apply electric energy from a power source such as ablasting machine or power line to the blasting circuit orto the open ends of the detonator wires. This electricalenergy flows through the wires to the detonator andcauses the resistance wire inside the detonator to heatthe primary explosives to the burning (explosion) tem-perature.

Initiation of Electric Detonators byRadio Frequency Energy

The possibility of premature explosions of electric det-onators due to RF energy is remote. Each year through-out the continental United States approximately 100million such detonators are used with few mishaps.However, there have been authenticated cases in whichdetonators were prematurely initiated by RF transmis-sion to the detonator wires. Subsequent investigationsrevealed that the instances would not have occurred ifproper safe distances from the RF sources had beenmaintained.

How RF Energy Initiates Electric Detonators

If the electric detonator wires are located in a strongRF field (near a transmitter that is radiating RF power),the usually insulated but unshielded leg wires or circuitwires will act as an antenna similar to that on a radioor TV set. That is true whether the circuit wires areconnected to a blasting machine or not, or whether theyare shunted (short circuited ends) or not shunted (open

1

ends). This antenna will absorb RF energy from thetransmitter RF field and the electric current transmittedto the detonator wires will flow into the detonator. (Seefigure 1.) Depending on the strength of the RF field andthe antenna configuration formed by the detonator wiresand its orientation, sufficient RF energy may be inducedin the wires to fire the electric detonator.

Figure 1

RF Energy Absorbed by Detonator Leg Wires

Radio Frequency Energy SourcesRadio frequency transmitters include citizens band (CB)

radios, cellular telephones, AM and FM radios, radar, andtelevision. These transmitters create powerful electromag-netic fields, which decrease in intensity with distance fromthe transmitter antenna. Tests have demonstrated thatelectric detonator wires, under particular conditions and

2

Electric Detonator

RF Ene

rgy

AM

Ant

enna

circumstances, may absorb enough electrical energy fromsuch fields to cause their explosion.

Mobile cellular telephones and CB radios pose unusualproblems. In recent years their use has greatly expanded.Mobile cellular telephones transmit RF energy duringsending and receiving. Additionally, modern technologyhas provided pages that transmit and receive RF energy.Safe distances are recommended for the Federal Com-munications Commission-approved, double sideband (4watts maximum output power) and single sideband (12watts peak envelope power) units in table VI.

Commercial AM Broadcast Transmitters

Commercial AM broadcast transmitters [0.535 to1.605 MHZ (Megahertz)] are potentially the most haz-ardous RF energy source. They combine high power andlow frequency so that there is little loss of induced RFenergy in the detonator lead wires. (See figure 2.)

Figure 2

Commercial AM Broadcast Transmitter(Vertically Polarized)

3

Frequency-modulated FM and TV Transmitters

Frequency-modulated FM and TV transmitters arenot likely to create hazardous situations. Although theirpower is extremely high and the antennas are horizon-tally polarized, their high frequency currents are rapid-ly attenuated in the detonator or leg wires. This RFsource employs antennas on very high towers, whichhave the additional effect of reducing the electromag-netic field at ground level. (See figure 3.)

Figure 3

Frequency-modulated FM and TV Transmitters(Horizontally Polarized)

4

Figure 4

Mobile Radios

Mobile Sources of RF Energy

Mobile radios and cellular telephones that transmitRF energy must be rated as a high potential hazardbecause, although their power is low, they can bebrought directly into a blasting area. (See figure 4.)Transmitting pagers also need to be considered.

5

HF and VHF Mobile Station(Citizens Band)

UHF Mobile Station(Long Range)

Figure 5 depicts other types of antennas associatedwith radio services.

Figure 5

Antennas Associated with Radio Services

6

Mobile Service Base StationMobile Service Base Station

Microwave Relays

The hazards of RF energy from microwave relays aresmall because they operate at a very high frequency,have a restricted radiation pattern, and are not normal-ly located within a blasting area. (See figure 6.)

Figure 6

A Microwave Relay

7

Radar Installations

Radar installations pose a hazard if blasting is donewithin the radar beam range. Radar installations radi-ate high power levels through the use of high gainantennas. (See figure 7.)

Figure 7

Radar Installations

Radio Frequency Pickup CircuitsElectric detonator wire layout can act as RF pickup

circuits for the radio frequencies used in AM radiobroadcasting and mobile operations. Two sensitive RFpickup circuits that might be created by lead wire con-figuration at electric blasting operations are known asthe dipole circuit and the long wire circuit.

8

Radar Service(Directional)

Radar Service(Revolving)

Dipole Pickup Circuit

The dipole circuit is depicted in figure 8. The dipolecircuit presents the most hazardous conditions when:

• The circuit wiring and/or electric detonator legwires are elevated several feet off the ground

• The length of this wiring is equal to one-half thewave length of the radio wave

• The electric detonator is located at a point where theRF current in the circuit wiring is at a maximum

Figure 8

Dipole Pickup Circuit

9

Several Feet

Ground

Long Wire

Detonator Wire

Detonator Wire

ElectricDetonator

Long Wire Pickup Circuit

The long wire circuit is shown in figure 9. The longwire circuit condition occurs when the electric detonatoris at one end of the wiring that:

• Is elevated in the air

• Has a length equivalent to one-quarter of thewavelength of the radio wave

• Is grounded to the earth through the electricdetonator

To determine the approximate radio wavelength, thetransmitter frequency in megahertz (MHz) is dividedinto 1,000. For example, a CB transmitter operates on afrequency of 26.96 to 27.33 MHz. This, divided into1,000, yields a wavelength of 36.6 to 37.1 feet.

Both of the previous circuits require that the leadline or detonator wires be suspended above the ground.Both of the circuits (antennas) achieve their maximumcurrent pickup when they are (1) parallel to a horizon-tal transmitting antenna (FM, TV, or amateur radio) or(2) pointed toward a vertical antenna (AM, mobile, etc.).

Figure 9

Long Wire Pickup Circuit

10

Several Feet

Detonator Wire Detonator Wire

Dipole

Ground

Electric Detonator

Loop Pickup Circuit

Another sensitive RF pickup circuit, and one com-monly encountered in blasting operations, is the loopcircuit. This circuit is sensitive to the magnetic portionof the electromagnetic wave. The loop circuit receivesthe maximum pickup when its long axis is placed in thedirection of the transmitting antenna. Safe distancetables for AM broadcast transmitters and mobile trans-mitters (both using vertical antennas) were derivedfrom the loop configuration. Figure 10 shows a pre-ferred case loop pickup circuit.

Figure 10

Loop Pickup Circuit—Preferred Case

11

Vertically Polarized

Transmitting Antenna

To Rest ofBlasting Layout

Charged HoleLong Axis

Blasting MachinePickup Area

Figure 11 shows an acceptable but less desirable con-figuration of loop and transmitting antenna. In general,the loop areas can be reduced by picking up both leadwires as in a duplex wire circuit and making all wiresplices as close to the ground as possible.

Figure 11

Loop Pickup Circuit—Acceptable but Less Desirable

General Precautions against RFEnergy Sources

The following list of precautions will reduce hazardsand increase safety for employees associated with blast-ing operations near RF energy sources.

12

Vertically PolarizedTransmitting Antenna

Blasting Machine

Charged Hole

Electric Detonator

Pickup Area

To Rest ofBlasting Layout

Long

Axis

1. When blasting electrically at a fixed location suchas a mine, quarry, or construction site, check to seewhether any radio transmitters are located closer toyour blasting site than the applicable separationrecommended in part 2 of this guide. Always be onthe alert for new transmitters. If possible, check eachtransmitter before it goes into service, to ensure itwill not pose a hazard to your blasting operation.

2. Keep mobile transmitters away from blastingareas. If transmitters are allowed on or near theblasting area, a strict policy must be set to ensurethat the transmitters are always turned off. Thisprecaution should be followed no matter what fre-quency or energy (watts) the transmitter employs.

3. If there is a choice, use the higher frequency bands(450-470 MHz) for mobile transmitters. RF pickupis less efficient at these frequencies than at thelower frequencies.

4. Avoid large loops in blasting wiring by running thelead wires parallel to each other and close together.

5. If loops are unavoidable, keep them small andorient them broadside towards the transmittingantenna.

6. Keep wires on the ground in blasting layouts. Bareconnecting points should be elevated slightly toprevent current leakage.

7. Arrange all lead lines out of the beam of directionaldevices such as radar or microwave relay stations.

8. If there is any doubt as to the RF hazards in relationto your blasting operations, a non-electric blastingsystem should be used until you have consulted witha person qualified in RF energy as it relates to blast-ing operations.

13

Transportation of Electric DetonatorsThe transportation of electric detonators does not cre-

ate a hazard from radio energy as long as the detona-tors are in their original containers. In their originalcontainers, the leg wires of the detonators are folded orcoiled so as to provide effective protection against cur-rent induction. Also, the metal body of a vehicle virtual-ly eliminates the penetration of RF energy.

If vehicles equipped with radio transmitters are usedto transport electric detonators to and from a job: (1)the caps should be carried in an enclosed metal boxlined with a non-sparking material and (2) the trans-mitter should be turned off when the caps are removedfrom the box.

Citizens Band Transmitters andCellular Telephones

CB radios are the most common radio communicationin existence today, but cellular telephone use is rapidlyincreasing. These radios often are in operation in bothmobile and base units within close proximity of blastingoperations. The units are used constantly on the high-ways, which are at times close to blasting operations.CBs are used by haul truck drivers, employees, andcompany officials.

Although the power (maximum 5 watts) is low on CBradios and cellular telephones, precautions should betaken in their use around electric blasting operations.CB radios and cellular telephones should not be operat-ed by anyone on the property during blast hole loadingoperations. In areas close to public roads where it isimpossible to control their usage, mine operators andconstruction crews should restrict the use of electricdetonators and use a non-electric blasting system.

14

2Tables of Distances—RF

Sources and Electric DetonatorsThe tables in this part of the guide are offered to

assist mine and quarry operators and commercialblasters. The tables include all of the obvious type of RFtransmitters that would be encountered around mines,quarries, and other blasting operations.

The tables were derived from analytical “worst case”calculations. They are based on an assumed 40-milli-watt no-fire level of commercial detonators. Field testshave shown the tables to be conservative, as would beexpected. There are numerous uncertainties involved infield tests respecting the efficiency of RF energy pickupand its delivery to the detonator. Thus, both the NorthCarolina Department of Labor and the Institute ofMakers of Explosives strongly recommend that thetables in this guide be followed.

Table I

Recommended Distances for CommercialAM Broadcast Transmitters

15

(0.535 to 1.605 MHz)

Transmitter Powera Minimum Distance

(watts) (feet)

Up to 4,000 8005,000 900

10,000 1,30025,000 2,00050,000b 2,900

100,000 4,100500,000 9,100

a. Power delivered to antennab. Maximum power of U.S. broadcast transmitters in this frequency

range

16

Table II

Recommended Distances for Transmitters up to 50 MHz

– – – – – – –

Table III

Recommended Distances for VHF TV and FMBroadcasting Transmitters

(Excluding AM Broadcast—Calculated for aSpecific Loop Pickup Configuration)a,b

Transmitter Powerc Minimum Distance

(watts) (feet)

100 800500 1,700

1,000 2,5005,000 5,500

50,000 17,000500,000d 55,000

a. Based on the configuration shown in figure 11 using 20.8 MHz,which is the most sensitive frequency

b. This table should be applied to international broadcast transmittersin the 10–25 MHz range

c. Power delivered to antennad. Present maximum for international broadcast

Effective Radiated Minimum Distance (feet)Power (watts) Channels 2 to 6 FM Radio Channels 7 to 13

Up to 1,000 1,000 800 60010,000 1,800 1,400 1,000

100,000a 3,200 2,600 1,900316,000b 4,300 3,400 2,500

1,000,000 5,800 4,600 3,30010,000,000 10,200 8,100 5,900

a. Present maximum power channels 2 to 6 and FMb. Present maximum power channels 7 to 13

17

Table IV

Recommended Distances for UHF TV Transmitters

Effective Radiated Power Minimum Distance

(watts) (feet)

Up to 10,000 6001,000,000 2,0005,000,000a 3,000

100,000,000 6,000

a. Present maximum power channels 14 to 83

18

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to r

ecen

t cha

nges

mad

e in

am

ateu

r ra

dio,

1,5

00 w

atts

of p

eak

pow

er o

utpu

t is

now

per

mis

sibl

e on

all

radi

o fr

eque

n-ci

es a

ssig

ned

to th

e am

ateu

r ra

dio

serv

ice.

Add

ition

al h

igh

freq

uenc

y ba

nds

have

als

o be

en a

ssig

ned

to th

e 30

-met

er b

and.

22

Ap

pen

dix

Sta

nd

ard

s a

nd

Reg

ula

tion

s fo

r th

e U

se o

f E

lect

ric

Det

ona

tors

aro

un

d R

ad

io F

req

uen

cy H

aza

rds

Sub

part

U—

Bla

stin

g an

d th

eU

se o

f Exp

losi

ves:

29

CF

R19

26.9

00(k

)—D

ue p

reca

utio

nssh

all b

e ta

ken

to p

reve

nt a

cci-

dent

al d

isch

arge

of e

lect

ricbl

astin

g ca

ps fr

om c

urre

ntin

duce

d by

rad

ar, r

adio

tran

s-m

itter

s, li

ghtn

ing,

adj

acen

tpo

wer

lines

, dus

t sto

rms,

or

othe

r so

urce

s of

ext

rane

ous

elec

tric

ity. T

hese

pre

caut

ions

shal

l inc

lude

: (1)

Det

onat

ors

shal

l be

shor

t-ci

rcui

ted

inho

les

whi

ch h

ave

been

prim

edan

d sh

unte

d un

til w

ired

into

the

blas

ing

circ

uit.

(3)(

i) T

hepr

omin

ent d

ispl

ay o

f ade

quat

esi

gns,

war

ning

aga

inst

the

use

of m

obile

rad

io tr

ansm

itter

s,on

all

road

s w

ithin

1,0

00 fe

et

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealth

Sta

nd

ard

s fo

r th

eC

on

stru

ctio

n In

du

stry

Sub

part

H—

Haz

ardo

usM

ater

ials

: 29

CF

R19

10.1

09(e

)(vi

i)—D

ue p

reca

u-tio

ns s

hall

be ta

ken

to p

reve

ntac

cide

ntal

dis

char

ge o

f ele

c-tr

ic b

last

ing

caps

from

cur

rent

indu

ced

by r

adar

, rad

io tr

ans-

mitt

ers,

ligh

tnin

g, a

djac

ent

pow

erlin

es, d

ust s

torm

s, o

rot

her

sour

ces

of e

xtra

neou

sel

ectr

icity

. The

se p

reca

utio

nssh

all i

nclu

de: (

b) T

he p

ostin

gof

sig

ns w

arni

ng a

gain

st th

eus

e of

mob

ile r

adio

tran

smit-

ters

on

all r

oads

with

in 3

50fe

et o

f the

bla

stin

g op

erat

ions

.

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealt

h S

tan

dar

ds

for

Gen

eral

Ind

ust

ry

Sam

e as

N.C

. Occ

upat

iona

lS

afet

y an

d H

ealth

Sta

ndar

dsfo

r G

ener

al In

dust

ry, 2

9 C

FR

1910

.109

(e)(

vii)

and

(e)(

vii)(

b)an

d th

e N

.C. O

ccup

atio

nal

Saf

ety

and

Hea

lth S

tand

ards

for

the

Con

stru

ctio

n In

dust

ry,

29 C

FR

192

6.90

0(k)

.

Fed

eral

Occ

up

atio

nal

Sa

fety

an

d H

ea

lth

Sta

nd

ard

s

Cha

pter

7—

Use

of E

xplo

sive

Mat

eria

ls fo

r B

last

ing:

7-1

.15

Pre

caut

ions

sha

ll be

take

n to

prev

ent a

ccid

enta

l dis

char

geof

ele

ctric

det

onat

ors

from

curr

ent i

nduc

ed b

y ra

dar

and

radi

o tr

ansm

itter

s, li

ghtn

ing,

adja

cent

pow

erlin

es, d

ust

stor

ms,

or

othe

r so

urce

s of

extr

aneo

us e

lect

ricity

. The

sepr

ecau

tions

sha

ll in

clud

e: (

a)T

he p

ostin

g of

sig

ns w

arni

ngag

ains

t the

use

of m

obile

radi

o tr

ansm

itter

s on

all

road

sw

ithin

350

feet

(10

7 m

) of

blas

ting

oper

atio

ns. (

b)O

bser

vanc

e of

the

late

st r

ec-

omm

enda

tions

with

reg

ard

tobl

astin

g in

the

vici

nity

of r

adio

tran

smitt

ers

or p

ower

lines

, as

Nat

ion

al F

ire

Co

de

23

of b

last

ing

oper

atio

ns. W

hen-

ever

adh

eren

ce to

the

1,00

0fo

ot d

ista

nce

wou

ld c

reat

e an

oper

atio

nal h

andi

cap,

a c

om-

pete

nt p

erso

n sh

all b

e co

nsul

t-ed

to e

valu

ate

the

part

icul

arsi

tuat

ion,

and

alte

rnat

ive

prov

i-si

ons

may

be

mad

e w

hich

are

adeq

uate

ly d

esig

ned

to p

re-

vent

any

pre

mat

ure

firin

g of

elec

tric

bla

stin

g ca

ps. A

desc

riptio

n of

any

suc

h al

ter-

nativ

es s

hall

be r

educ

ed to

writ

ing

and

shal

l be

cert

ified

as

mee

ting

the

purp

oses

of t

his

subd

ivis

ion

by th

e co

mpe

tent

pers

on c

onsu

lted.

The

desc

riptio

n sh

all b

e m

ain-

tain

ed a

t the

con

stru

ctio

n si

tedu

ring

the

dura

tion

of th

ew

ork,

and

sha

ll be

ava

ilabl

e

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealth

Sta

nd

ard

s fo

r th

eC

on

stru

ctio

n In

du

stry

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealt

h S

tan

dar

ds

for

Gen

eral

Ind

ust

ry

Fed

eral

Occ

up

atio

nal

Sa

fety

an

d H

ea

lth

Sta

nd

ard

s

set f

orth

in IM

E S

afet

y Li

brar

yP

ublic

atio

n N

o. 2

0, S

afet

yG

uide

for

the

Pre

vent

ion

ofR

adio

Fre

quen

cy H

azar

ds in

the

Use

of E

lect

ric B

last

ing

Cap

s.Nat

ion

al F

ire

Co

de

24

for

insp

ectio

n by

rep

rese

nta-

tives

of t

he C

omm

issi

oner

of

Labo

r. (

3)(ii

) S

peci

men

s of

sign

s w

hich

wou

ld m

eet t

here

quire

men

ts o

f sub

divi

sion

(i)

of th

is s

ubpa

ragr

aph

(3)

are

the

follo

win

g:

(4)

Ens

urin

g th

at m

obile

rad

iotr

ansm

itter

s w

hich

are

less

than

100

feet

aw

ay fr

om e

lec-

tric

bla

stin

g ca

ps, i

n ot

her

than

orig

inal

con

tain

er, s

hall

bede

ener

gize

d an

d ef

fect

ivel

ylo

cked

.No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealth

Sta

nd

ard

s fo

r th

eC

on

stru

ctio

n In

du

stry

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealt

h S

tan

dar

ds

for

Gen

eral

Ind

ust

ry

Fed

eral

Occ

up

atio

nal

Sa

fety

an

d H

ea

lth

Sta

nd

ard

sN

atio

nal

Fir

e C

od

e

BL

AS

TIN

GZ

ON

E10

00 F

T

TU

RN

OF

F2-

WA

YR

AD

IO

Abo

ut 4

8" X

48"

Abo

ut 4

2" X

36"

25

(5)

Com

plia

nce

with

the

rec-

omm

enda

tions

of t

he In

stitu

teof

Mak

ers

of E

xplo

sive

s w

ithre

gard

to b

last

ing

in th

e vi

cini

-ty

of r

adio

tran

smitt

ers

as s

tip-

ulat

ed in

Rad

io F

requ

ency

Ene

rgy—

A P

oten

tial H

azar

din

the

Use

of E

lect

ric B

last

ing

Cap

s IM

E P

ublic

atio

n N

o. 2

0.

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealth

Sta

nd

ard

s fo

r th

eC

on

stru

ctio

n In

du

stry

No

rth

Car

olin

aO

ccu

pat

ion

al S

afet

y an

dH

ealt

h S

tan

dar

ds

for

Gen

eral

Ind

ust

ry

Fed

eral

Occ

up

atio

nal

Sa

fety

an

d H

ea

lth

Sta

nd

ard

sN

atio

nal

Fir

e C

od

e

GlossaryAmateur Service. A service of intercommunications andtechnical investigations carried on by duly authorizedpersons interested in radio techniques.

Aviation Services. Services of fixed and land stations andmobile stations on land and on board aircraft primarilyfor the safe expedition and economical operation of air-craft.

Broadcasting Service. A radio communication service inwhich the transmissions are intended for direct recep-tion by the general public.

Citizens Band Radio. A radio communication service offixed, land, and mobile stations intended for personal orbusiness radio communication, radio signaling, (and)control of remote objects or devices.

Fixed Service. A service of radio communication betweenspecified fixed points.

Fixed Station. A station in the fixed service.

International Broadcast Service. A service whosetransmissions are intended to be received directly bythe general public in foreign countries.

Land Station. A station in the mobile service intendedto be used while in motion or during halts at unspeci-fied points.

Maritime Services. Services intended for maritime radiocommunication and including fixed stations, land sta-tions, and mobile stations on land and on board ships.

Megahertz. 1,000,000 cycles per second.

Mobile Service. A service of radio communicationbetween mobile and land stations, or between mobilestations.

26

Mobile Station. A station in the mobile service intendedto be used while in motion or during halts at unspeci-fied points.

Standard Frequency Terms and Bands.High Frequency Band (HF): 3–30 MHzGigahertz (GHz): 1 GHz = 1,000,000,000 cycles per secondMedium Frequency Band (MF): 0.3–3 MHzMegahertz (MHz): 1 MHz = 1,000,000 cycles per secondUltra High Frequency Band (UHF): 300–3,000 MHzVery High Frequency Band (VHF): 30–300 MHz

27

ReferencesAtlas Powder Company. Handbook of Electric Blasting.

Dallas, Texas, 1985.

E.I. Dupont de Nemours. Dupont’s Blasters’ Handbook.175th Anniversary Ed. Wilmington, Delaware, 1977.

Institute of Makers of Explosives. Safety LibraryPublication No. 20. Washington, D.C., 1988.

National Fire Code. Use of Explosive Material forBlasting. Chapter 7.

North Carolina OSHA Standards for General Industry.29 CFR 1910.

North Carolina OSHA Standards for the ConstructionIndustry. 29 CFR 1926.

28

The following industry guides are available from the N.C. Depart-ment of Labor’s Division of Occupational Safety and Health:1#1. A Guide to Safety in Confined Spaces1#2. A Guide to Procedures of the Safety and Health Review Board of North

Carolina1#3. A Guide to Machine Safeguarding1#4. A Guide to OSHA in North Carolina1#5. A Guide for Persons Employed in Cotton Dust Environments1#6. A Guide to Lead Exposure in the Construction Industry1#7. A Guide to Bloodborne Pathogens in the Workplace1#8. A Guide to Voluntary Training and Training Requirements in OSHA

Standards1#9. A Guide to Ergonomics#10. A Guide to Farm Safety and Health#11. A Guide to Radio Frequency Hazards With Electric Detonators#12. A Guide to Forklift Operator Training#13. A Guide to the Safe Storage of Explosive Materials#14. A Guide to the OSHA Excavations Standard#15. A Guide to Developing and Maintaining an Effective Hearing

Conservation Program#17. A Guide to Asbestos for Industry#18. A Guide to Electrical Safety#19. A Guide to Occupational Exposure to Wood and Wood Dust#20. A Guide to Crane Safety#21. A Guide to School Safety and Health#23. A Guide to Working With Electricity#25. A Guide to Personal Protective Equipment#26. A Guide to Manual Materials Handling and Back Safety#27. A Guide to the Control of Hazardous Energy (Lockout/Tagout)#28. A Guide to Eye Wash and Safety Shower Facilities#29. A Guide to Safety and Health in Feed and Grain Mills#30. A Guide to Working With Corrosive Substances#31. A Guide to Formaldehyde#32. A Guide to Fall Prevention in Industry#33. A Guide to Office Safety and Health#34. A Guide to Safety and Health in the Poultry Industry#35. A Guide to Preventing Heat Stress#36. A Guide to the Safe Use of Escalators and Elevators#37. A Guide to Boilers and Pressure Vessels#38. A Guide to Safe Scaffolding#39. A Guide to Safety in the Textile Industry#40. A Guide to Emergency Action Planning#41. A Guide to OSHA for Small Businesses in North Carolina

Occupational Safety and Health (OSH)Sources of Information

You may call 1-800-NC-LABOR to reach any division of the N.C.Department of Labor; or visit the NCDOL home page on the World WideWeb, Internet Web site address: http://www.nclabor.com.N.C. Division of Occupational Safety and Health

Mailing Address: Physical Location:4 W. Edenton St. 111 Hillsborough St.Raleigh, NC 27601-1092 (Old Revenue Building, 3rd Floor)Local Telephone: (919) 807-2900 Fax: (919) 807-2856

For information concerning education, training and interpretations of occupationalsafety and health standards contact:Bureau of Education, Training and Technical Assistance

Mailing Address: Physical Location:4 W. Edenton St. 111 Hillsborough St.Raleigh, NC 27601-1092 (Old Revenue Building, 4th Floor)Telephone: (919) 807-2875 Fax: (919) 807-2876

For information concerning occupational safety and health consultative servicesand safety awards programs contact:Bureau of Consultative Services

Mailing Address: Physical Location:4 W. Edenton St. 111 Hillsborough St.Raleigh, NC 27601-1092 (Old Revenue Building, 3rd Floor)Telephone: (919) 807-2899 Fax: (919) 807-2902

For information concerning migrant housing inspections and other related activi-ties contact:Agricultural Safety and Health Bureau

Mailing Address: Physical Location:4 W. Edenton St. 111 Hillsborough St.Raleigh, NC 27601-1092 (Old Revenue Building, 2nd Floor)Telephone: (919) 807-2923 Fax: (919) 807-2924

For information concerning occupational safety and health compliance contact:Safety and Health Compliance District Offices

Raleigh District OfficeTelephone: Safety (919) 662-4597 Fax: (919) 662-4709

Health (919) 662-4711Charlotte District Office(901 Blairhill Road, Suite 200, Charlotte, NC 28217-1578)Telephone: Safety (704) 342-6163 Fax: (704) 342-5919Winston-Salem District Office(901 Peters Creek Parkway, Winston-Salem, NC 27103-4551)Telephone: Safety (336) 761-2700 Fax: (336) 761-2326

Health (336) 761-2700 Fax: (336) 761-2130Wilmington District Office(1200 N. 23rd St., Suite 205, Wilmington, NC 28405-1824)Telephone: (910) 251-2678 Fax: (910) 251-2654Asheville District Office(204 Charlotte Highway, Suite B, Asheville, NC 28803-8681)Telephone: (828) 299-8232 Fax: (828) 299-8266

***To make an OSHA Complaint, OSH Complaint Desk: (919) 807-2796***For statistical information concerning program activities contact:Planning, Statistics and Information Management

Mailing Address: Physical Location:4 W. Edenton St. 111 Hillsborough St.Raleigh, NC 27601-1092 (Old Revenue Building, 2nd Floor)Telephone: (919) 807-2950 Fax: (919) 807-2951

For information about books, periodicals, vertical files, videos, films, audio/slidesets and computer databases contact:N.C. Department of Labor Library

Mailing Address: Physical Location:4 W. Edenton St. 111 Hillsborough St.Raleigh, NC 27601-1092 (Old Revenue Building, 5th Floor)Telephone: (919) 807-2848 Fax: (919) 807-2849

N.C. Department of Labor (Other than OSH)4 W. Edenton St.Raleigh, NC 27601-1092Telephone: (919) 733-7166 Fax: (919) 733-6197