Signal Construction Grounding New Hire Basics - Railroad Controls ...

Signal Construction Grounding 

New Hire Basics 

Railroad Controls Limited & ERICO ® 

Rev. 4/29/11

Why is Grounding Important? 

• Grounding techniques applied in 

Railroad Signaling address employee 

Safety & protect Signal Equipment 

from damage. 

• Railroads deal with Electric, 

Electromagnetic, Electrostatic and 

even sunspot induced interference. 

• As a new hire, you will be installing 

important pieces of the grounding 

puzzle.

Lightning is Beautiful When There Isn’t a Railroad Track Around!

Extremely 

High Voltage 

The Killing Zone can extend 

several hundred yards from 

the lightning strike 

A characteristic lightning strike 

spreads radially from the point 

of strike with a typical 

frequency of 640hz. The 

voltage gradient through 

ground can be lethal due to the 

difference in voltage potential 

within only a couple of feet in 

this killing zone. 

Low 

Voltage

Extremely 

High Voltage 

(Windmill on the open prairie) 

It is not uncommon for cattle to be 

electrocuted standing on wet ground 

in the vicinity of a lightning strike. The 

voltage gradient is due to the fact the 

soil is not a perfect “ground”.

A small lightning strike was captured by a City of Roseville, CA 

intersection camera. The strike came into the top of the city light 

pole near the UPRR signal cantilever. RCL has an Automated 

Horn System installed here which happened to have a horn 

mounted on this same light pole. Although the AHS did not have 

any damage, one railroad grade crossing predictor did.

Surge Interference Potentials: 

line to line; line to ground, rail to rail, rail to 

ground; ground to ground, and basically 

between ground and/or between every 

signal circuit, structure or component we 

install or touch. MOO

DANGER 

DO NOT TOUCH SIGNAL 

CIRCUITS INSIDE OR 

OUTSIDE OF SIGNAL 

HOUSINGS DURING AN 

ELECTRICAL STORM! 

This is like playing 

Russian Roulette

Refer to BNSF Standard 

DK-0002.00: 

Each RCL crew will have 

available both a BNSF 

Standards & Recommended 

Practices Manual and a Signal 

Instructions Manual. 

Let’s first discuss the ground 

rod and the exothermic ground 

rod connection.

Refer to BNSF Standard DK- 

0002: 

The 5/8” diameter, 5’ long Erico 

ground rods have a special 

thread-less coupler which is 

used to add additional rods 

when driving into the ground. A 

minimum depth of 10’ must be 

achieved. 

Ground rods are copper-plated 

steel rods. 

Note that these photos depict 

rods which are NOT yet properly 

cleaned for insertion.

Installing Ground Rods 

RCL uses the Eritech® 

Ground Rod Driver or an 

approved electric hammer 

driver to eliminate safety 

issues when installing 

ground rods. 

RCL does NOT allow the 

use of conventional fence 

post type drivers which 

expose us to personal 

injury.

Cadweld ® Products 

used on Railroads ALL 

have the F80 weld 

metal powders which 

have the yellow caps. 

BNSF uses #6awg soft 

drawn copper for their 

external ground connections 

on signals & bungalows.

CADWELD ® 

ONE-SHOT Process

How Hot is the Cadweld? 

• The reaction in the crucible reaches temperatures in 

excess of 4000°F 

• The molten welding material is hot enough to exceed 

the melting point of steel when it reaches the rail (or 

ground rod), i.e. > 2750°F (ref. AISI C1020 steel).

Safety First 

• Always wear 

protective safety 

glasses and gloves 

while working with 

CADWELD 

exothermic products

NOTE: 

Yellow Cap 

Rail Applications 

One-Shot Materials 

• System requires a 

CADWELD One- 

Shot ceramic mold, 

welding material, 

wire brush for 

cleaning, flint igniter, 

and propane torch.

Inspect Ceramic Mold 

• Check to ensure 

ceramic mold is not 

broken or cracked 

which would cause 

leakage of molten 

weld metal during 

the reaction.

Torch Dry Conductors 

• Conductors should 

be clean and dry 

before the 

connection is made. 

Use a propane torch 

to dry conductor and 

ground rod.

Wire Brush Conductors 

• Use a wire brush to 

further prepare 

conductor.

Wire Brush Conductors 

• Use a wire brush to 

further prepare 

ground rod.

Twist Onto Rod 

• Gently turn the 

CADWELD One- 

Shot onto the 

ground rod until the 

ground rod reaches 

the stopper and 

cannot to any 

further.

Insert Conductors 

• Inset the conductors 

and position them 

for the connection.

Insert Conductors 

• Depending upon 

the type of oneshot 

used, insert 

wires into each 

whether used or 

not to ensure the 

weld metal is held 

in the weld.

Dish Side UP 

• Place the steel disk 

into the CADWELD 

One-Shot with the 

concave side facing 

up.

Proper Fit 

• Ensure that the steel 

disk is properly 

seated inside the 

CADWELD One- 

Shot mold. This 

forms the crucible 

for the reaction.

NOTE: 

Yellow Cap 

Rail Applications 

Blue Tube 

• Next, take the tube 

of welding material 

included in the 

CADWELD One- 

Shot package and 

remove the lid over 

the crucible.

Weld Material 

• Dump the loose 

welding material 

powder into the 

CADWELD One- 

Shot.

Mold Cover 

• Place the cover on 

the top of the 

CADWELD One- 

Shot.

Starting Material 

• The bottom of the 

weld material tube 

contains the 

compressed 

material (starting 

material). Tap tube 

to loosen.

Starting Material 

• Pour the starting 

material onto the 

CADWELD One- 

Shot cover.

Start the Reaction 

• Ignite the starting 

material on the mold 

cover. Withdraw the 

igniter quickly to 

prevent fouling of 

the flint.

Break Ceramic Mold 

• Break the ceramic 

CADWELD One- 

Shot mold off the 

connection. Avoid 

contact with hot 

materials.

Inspect Connection 

• See “Installers & 

Inspectors Guide” to 

see whether a 

quality connection 

has been made.

Successful Connection 

• You are ready to 

make another 

CADWELD One- 

Shot connection.

Need More Info? 

ERICO International 

1-800-447-RAIL 

http://www.erico.com

Erico Cadweld Welders: 

We will also use Cadweld Welders 

for splicing ground wires and for 

welding to ground rods, structures, 

and the rail. These have re-useable 

graphite molds. 

Always wear the appropriate 

personal protective equipment.

Erico Cadweld 

Exothermic Process: 

Here is a photo of a rail head 

bond being applied with rail 

head welders. 

Let’s talk about the safety 

concerns we see here: 

• Hinged crucible lids not in 

place. 

• Positioned on wrong side 

of the welder. 

• Sleeves rolled up. 

• Bonding tray could 

explode. 

• Goggles/face shield. 

• Hand on the rail. 

• Gasoline grinder.

Erico Cadweld 

Exothermic Process: 

Here is a photo of a One- 

Shot just applied on a 

ground rod. 

DANGER: 

NEVER ignite the crucible 

when ANY moisture is 

present on the rail, ground 

rod, in the mold, or if it is 

raining or snowing. 

An EXPLOSION will occur 

spraying hot molten brass 

at a temperature in excess 

of 2500°.


DK-0002.00: 

Signal masts we will install are 

provided with a special 

aluminum to copper ground 

wire transition permanently 

attached to the mast. 

Although aluminum to copper 

connections have difficulty 

maintaining a good electrical 

connection due to oxidation, 

the aluminum sleeve is “spun” 

onto the copper at high speed 

and sealed providing an 

excellent connection.


DK-0002: 

Ground rods will be installed 

outside of each of the four 

corners of a signal bungalow 

and two rods will be installed at 

a signal case. 

All of BNSF bungalows and 

cases have an aluminum to 

copper ground wire connection 

welded underneath the 

bungalow. These must be 

brought out and welded to the 

ground rods along with a 

#6awg counterpoise 

connecting all ground rods.

What is a Counterpoise? 

• A counterpoise is the 

ground wire connecting all 

the ground rods around 

the bungalow or case. This 

provides employee 

protection by keeping the 

ground potential just 

outside the bungalow the 

same as that of the 

bungalow itself. It also aids 

in dispersing ground 

currents from the 

bungalow.

• The counterpoise perimeter 

ground wiring should be 

installed a minimum of 12” from 

the perimeter of the bungalow 

or case and should be in soil 

approximately 4” to 6” under 

the ground level of the dress 

rock at the bungalow or case. 

Bungalow 

Frame Grounding 

pigtails 

Counterpoise 

Ground Wire 

Ground 

Rods

Tower Grounding grid will 

be connected to the 

bungalow grounding grid. 

Intermediate ground rods 

will be installed every 10 ft. 

Refer to BNSF IS/Telecom 

Instructions.

If the tower ground 

were NOT connected 

to the bungalow 

ground grid, 

electrocution could 

occur if touching both 

the tower and the 

bungalow.

Make gradual, sweeping bends in ground conductors. When 

heavy ground current flows in a ground conductor, sharp 

bends act as a resistance to the magnetic field produced 

around the ground conductor by the surge current flowing to 

ground creating a huge difference of potential at the bend. This 

can elevate the voltage potential of our ground buss damaging 

equipment. 

Surge 

current 

flowing to 

ground 

Concentrated 

lines of flux which 

try to straighten 

the ground wire 

Extremely high 

difference of potential 

and smoked 

equipment 

Gradual 

bends can 

make a big 

difference

If an older bungalow is 

encountered which has the 

grounding pigtails on the 

terminal board frame, bring 

these through the hole in 

the floor directly below the 

pigtail and then weld them 

to the closest ground rods of 

the counterpoise.

Refer to BNSF Standard DK-0002 or your Supervisor for other 

important grounding information.


DR-0014: 

To reduce surge current coupling 

into adjacent conductors, keep 

underground cable conductors a 

safe distance away from both 

grounding conductors & “Clean” 

bungalow wiring. 

If you have to run underground 

cable parallel to clean house 

wiring, maintain a distance greater 

than 8”. Crossings at 90° have 

little coupling effect to surge 

currents, however, maintain a 

minimum 8” distance whenever 

possible.

Induced 

Current 

Flux 

Field 

Builds 

Heavy 

Ground 

Current 

Refer to BNSF Standard DR- 

0014: 

As heavy current flows through 

any conductor, lines of flux 

build around the conductor. As 

these lines of flux cut across 

adjacent parallel conductors, 

current flow in the opposite 

direction will be induced in any 

adjacent conductor. 

The closer the adjacent 

conductor, the logarithmically 

greater the induced current. 

Therefore, maintain a minimum 

8” distance whenever possible.

Refer to BNSF Standard DR- 

0014: 

Underground cables leaving 

the bungalow en route to 

signals, switches and other 

signal enclosures will have the 

10mil bronze cable gopher 

shield grounded in the 

bungalow on only one end of 

the cable. 

(Refer to RCL Basic Cable 

Installation program for 

installation of this shield 

grounding connection.)


DR-0014: 

Install cable and arresters as 

shown which provide for the 

following: 

• Underground cable conductor 

can be isolated by opening the 

gold test nut for megging tests. 

• The Lightning Arrester can be 

replaced WITHOUT 

disarranging the circuit. 

• The Equalizer can be replaced 

WITHOUT disarranging the 

circuit.

Refer to BNSF Signal 

Instruction 14.1: 

When installing lightning 

arresters which have serrated 

teeth, orient them with the teeth 

pointed upward or horizontal. 

These teeth will melt away 

maintaining a ground free zone 

once the surge is dissipated. 

Otherwise, the molten slag can 

drip together and short the 

arrester to ground. 

BNSF will maintain ground 

rods at a minimum of 25Ω to 

ground.

There are many 

different types of 

lightning arresters and 

equalizers. Refer to the 

location circuit plan for 

proper application. 

Always install the 

arresters once the 

cable is terminated to 

protect the equipment. 

Legend: 

1 

2 

3 

2 

Heavy Duty Track Arrester – Safetran 022615-1X UP 

Heavy Duty Equalizer – Safetran 022700 -1X 

1 

1 

3 

To Track 

Clearview Lightning Arrester – Safetran 022485-28X UP 

To Signal, 

Switch, Electric 

Lock, or other 

B12 or B24 

circuit.

The arresters used on signal 

circuits are an “Air Gap” type. 

They are designed to maintain 

signal circuits free from ground 

while still doing their job.

Equalizer 

Clearview 

Lightning 

Arrester – 

Teeth UP

Each conductor 

entering a BNSF 

bungalow from the 

outside will be 

terminated and have a 

lightning arrestor, 

surge suppressor, or a 

combination of 

arrestor/equalizer at 

the entry point. 

There may easily be 

over 100 conductors 

to terminate and 

arrest.

Track wire terminations with Heavy Duty Lightening 

Arrestors & Equalizers with wires properly tagged.

GROUNDING REMINDERS 

• Make gradual, sweeping bends in 

ground conductors 

• Keep cable conductors greater than 

8” from grounding conductors or 

“clean” conductors when running 

parallel to each other. 

• Do NOT run grounding conductors 

within the same riser pipe as cables. 

• Weld all ground rod connections 

• Properly install all lightning & surge 

arresters to complete the process.

GROUNDING QUESTIONS?

Signal Construction Grounding New Hire Basics - Railroad Controls ...

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