Ballast FAQ

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Ballast Frequently Asked Questions

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1.001 What might cause a ballast to fail?

1.002 What is Class P Protection?

1.003 How can I tell if a thermal protector is operating?

1.004 What can I do to stop or prevent thermal cycling?

1.005 What sections of UL48 (9/3/98) require ½” elevation of ballasts apply to me?

1.006 What can I do to fix a lamp that won't start or fails early?

1.007 I just installed a France ballast and the lamps are “swirling” inside.

1.008 Can a France sign ballast be flashed or dimmed?

1.009 What power factor should I expect from a from a sign ballast?

1.010 How Do You Calculate the Cost of Operating a Sign Ballast?

1.001 What might cause a ballast to fail?

Extreme heat or moisture

Mount ballast in the coolest area of the sign
Mount ballast where it is not exposed to water (standing, spray or drips)
Make sure ballast makes metal-to-metal contact for proper heat dissipation
Make sure there is adequate ventilation provided in the sign
Provide adequate drainage in the sign

Improper input voltage

Make sure input voltage is +/- 5% of the ballast’s rated value

Improper wiring

Refer to the ballast label to ensure proper wiring for number and length of lamps
Tripped breakers/blown fuses suggest a circuit short

Improper grounding

Make sure the ballast and the sign are properly grounded Connect the white lead of the ballast to the neutral side of the power supply

Absent filament voltage

Heavy darkening at the lamp ends indicates an improper or absent filament voltage
Inspect lamp sockets for evidence of arcing, misalignment, foreign material, breakage, etc. Replace any defective sockets; clean others. Check all secondary leads for damage or deterioration.

1.002 What is Class P Protection?

Excessive overheating of a ballast might create a fire or shock hazard. Class P Protection is an Underwriters Laboratories requirement created to address this potential overheating of a ballast either because of ballast failure or during operation in an abnormally high temperature situation.

In magnetic ballasts, a temperature-activated switch is used to help conform to the UL test requirements for Class P. This switch removes primary power from the ballast when the ballast is being exposed to excessively high temperatures for whatever reason. After the ballast cools down, this switch resets automatically and the ballast attempts to operate again.

UL also requires Class P Proection in electronic fluorescent ballasts. Some of these ballasts may use a temperature-activated switch to conform, but many only use circuitry that will not create temperatures or situations that can cause fire or electical shock. This is called "inherently protection." Additional UL requirements apply to ballasts utilizing inherent protection.

1.003 How can I tell if the temperature-activated switch is operating?
It is very likely that the ballast has been installed in a too-hot environment, and is thermally cycling, if the lamps are cycling on and off in a very predictable pattern over a long period of time (30 minutes to hours).

1.004 What can I do to stop or prevent thermal cycling?

Increase air circulation to the ballast by adding vents or louvers to the sign.
Locate the ballast in a cooler portion of the installation such as lower side of the sign and on a surface the other side of which faces the outside environment.
Mount the ballast so there is metal-to-metal contact between the ballast and the sign body.
Do not double-nut mount a ballast. If you are required to mount a ballast in a location requiring spacing between the ballast and the sign, place ½" thick of solid metal between the ballast and sign body. Metal-to-metal contact is always preferred.
Do not install fewer feet of lamps than ballast rating.

1.005 What sections of UL48 (9/3/98) require ½” elevation of ballasts apply to me?
Paragraph 27.2.6 of UL48 (Sept. 3, 1998 revision) states that in an outdoor sign, a non-weatherproof ballast must be raised at least ½" off the bottom of the sign.

1.006 What can I do to fix a lamp that won't start or fails early?

Use only HO (high output, 800 mA), T12 lamps. Do not use energy-saving, 1 amp HO, 1.5 amp HO lamps on 800 mA ballasts
Do not use energy-saving lamps!
Total footage of lamps greater than rated load or ballast.
Heater windings not properly connected to lamp holder – check ballast label for wiring diagrams. Assure heater voltage is present across all lamp holders (should be 3.8 to 4.5 volts). Heater voltage problems are usually accompanied by short term end blackening of the lamps.
Ballast and/or sign not grounded – assure proper grounding.
Bad or damaged lamp holders
Low primary voltage – verify primary voltage is rated +/- 5%.
Check for pinched wiring between ballast and lamps.
Install starting strips. These create an electric field between lamp and strip to help break down gas in the tube and aids lamp starting. Two types:

1" Wide mounted within 1" of lamp
1/2" Wide, 1/2" from lamp also works

Make sure to ground the starting strip.

1.007 I just installed a France ballast and the lamps are “swirling” inside.

New lamps need at least 100 hours of “seasoning” for stable operation. Try turning the lamps on and off several times. This will usually correct the problem.

1.008 Can a France sign ballast be flashed or dimmed?

No.

1.009 What power factor should I expect from a from a sign ballast?

The line power factor for all France sign ballasts is greater than 90%. To be considered high power factor, power companies, listing agencies, etc. usually require that the power factor be at least 90%.

1.010 How Do You Calculate the Cost of Operating a Sign Ballast?
Since all France ballasts present a high power factor to the line, the power drawn from the line is approximately equal to:

P = Vp x Ip

Where:

P = watts

Vp = primary voltage

Ip = primary current

So, if the 688DR ballast was fully loaded the input power would be:

P = 120 x 5 = 600 watts

This calculation is only valid if the ballast is fully loaded. For instance, a 688DR ballast is fully loaded when 6, 8 foot high output (800 mA) lamps are connnected to the ballast. This constitutes a total lamp footage of 48 feet. If less than 48 feet of lamps are used then the input power may be approximated by scaling:

P = Vp x Ip x (actual footage operated)
fully loaded footage

So, if the 688DR ballast was used to operate 6, 6 ft lamps (total = 36 feet) the input power would be:

P = 120 x 5 x 36/48 = 450 watts

To calculate the cost of operating a sign ballast:

Use one of the above methods to calculate power (watts) and plug the result into the following formula:

$/day = watts x (hrs/day) x ($/kwh)
1000