Fuses Made Simple™- Control Circuits
The easiest and fastest way to select and specify the right control circuit fuse
Bussmann’s Fuses Made Simple program provides the easiest and fastest way to select and specify the right fuse. Whether it’s branch circuit or control circuit (supplemental) fuses, we take the guesswork out of selecting the right fuse. What’s more, we make it simple to replace fuses with six color groups (categorized by voltage rating)--all while enhancing the safety of the electrical system.
Find the control circuit fuse you need in three simple steps:
Select the fuse type. Select from time-delay (for inductive loads) or fast-acting (for resistive loads).
Select the voltage rating needed. Keep in mind that fuse voltage rating must be equal to or greater than the circuit voltage.
3. Interrupting Rating
Verify that the interrupting rating of the fuse selected is sufficient for the circuit application. Keep in mind that the interrupting rating must be equal to or greater than the available short-circuit current.
Use the table below to find and select the right control circuit fuse, click on the fuse family for product details
|Fuse Type||Maximum Voltage Rating||Fuse Family||Color Code||Amp Range||Interrupting Rating|
|600Vac||Recommend using Low-Peak LP-CC Class CC fuses*|
|500Vac||FNQ||Orange||1/10 to 30A||10kA|
|FNM||Green||1/10 to 1A||35A|
|FNM||Green||1-1/8 to 3-1/2A||100A|
|FNM||Green||4 to 10A||200A|
|FNM||Green||12 to 30A||10kA|
|FNA2||Green||1/10 to 8/10A||35A|
|FNA2||Green||1 to 6A||200A|
|125Vac||FNA2||Blue||6-1/4 to 15A||10kA|
|48Vac||Upgrade to 125Vac|
|32Vac||FNA2||Grey||20 to 30A||1kA|
||KTK||Black||1/10 to 30A||100kA|
|KLM3||Black||1/10 to 30A||100kA|
|BBS1||Black||1/10 to 6A||10kA|
|500Vac||Upgrade to 600Vac|
|BAF||Green||1/4 to 1A||35A|
|125Vac||Upgrade to 250Vac|
|For ultimate protection, any of the control circuit fuses above can be upgraded to a branch circuit Low-Peak LP-CC Class CC fuse.*|
1. Fuse is 1-3⁄8” long.
2. Fuse is pin indicating .
3. Fuse is also rated for 600Vdc, 50kA interrupting rating .
* For primary protection of control transformers, use FNQ-R.
** For interrupting rating, contact factory.
Importance of voltage rating and interrupting rating
Control circuit fuses have many different voltage ratings, ranging from 32Vac to 600Vac, and interrupting ratings up to 100kA. Because their physical size does not vary with voltage or interrupting ratings, the most frequent cause of misapplication is due to improper voltage or interrupting rating selection. This leads to compromised system integrity, and equipment and personnel safety. It is important to note, though, that when a fuse is applied beyond its ratings, there may not be any initial indicators. Adverse consequences typically result when a system fault occurs and an improperly sized fuse attempts to interrupt an overcurrent event.
Voltage rating is extremely important. The proper application of an overcurrent protective device, according to its voltage rating, requires that the voltage rating of the device be equal to or greater than the system voltage.It can be higher but not lower. For instance, a 600V fuse can be used to safely protect a 208V circuit.However, when an overcurrent protective device is applied beyond its rating, there may be potential for fire and arcing energy, which poses a severe fire risk to other components in the panel.
Interrupting rating is also of critical importance. An overcurrent protective device must be able to withstand the destructive energy of short-circuit currents of the equipment it is protecting. If a fault current exceeds a level beyond the capacity of the protective device, the device may actually rupture, causing additional damage. It is therefore important when applying a fuse to use one that can sustain the largest potential short-circuit currents. Failure to apply fuses with the appropriate interrupting rating can be a serious safety hazard.
Fuses Made Simple™ - Control Circuits helps enhance safety
Bussmann's Fuses Made Simple - Control Circuits helps minimize the risk of misapplication by clearly and consistently indicating both the voltage rating and interrupting rating on the fuse label. The voltage rating is easily identified by both the color code band and the large print on the fuse label. Additionally, the interrupting rating is printed on the side of each fuse.
Color-coded by voltage
Each fuse label has a unique identifying color band that represents the fuse’s maximum voltage rating. When it’s time to replace a fuse, Bussmann makes it easy to search for the replacement. Select the voltage needed by simply looking for the Bussmann fuse with the right color band in the storage bin. This narrows the search and speeds replacement time.
- 600Vac - Black (KTK, KLM BBS)
- 500Vac - Orange (FNQ)
- 250Vac - Green (FNM, FNA2, BAF, BBS1, MIC2)
- 125Vac - Blue (FNA2)
- 48Vac - Purple (BBS1)
- 32Vac - Grey (FNA2, MIC2)
1. Fuse is 1-3/8" long.
2. Fuse is pin indicating.
3. Fuse is also rated for 600Vdc.
Consistent look for each label
Every fuse label now has a consistent look. Critical fuse information is presented in an easy-to-read format across the entire Bussmann control circuit fuse portfolio to help speed replacement.