VTI FDP Series - Fused Distribution Panel

Wall-mounted High-speed Fused Power Distribution Unit

FDP unit, door open
30 Circuit Main Breaker FDP with the Circuit Breaker Lockout Kit
FDP - 125V with hinged door closed
FDP unit mounted with doors closed
19 inch FDP unit
UL Label Supplied US/Canada

VTI's  Fused Distribution Panel (FDP) is designed to provide electrical power distribution in applications requiring high-speed clearing of branch-circuit load faults from the supply source. The FDP is available for single-phase and three-phase input voltages and can accomodate single, double, or three pole switches, up to 42 pole positions per unit (or more by special order). Each branch switch output feeds a high-speed, sub-cycle clearing fuse which in turn feeds the load.

The VTI Fused Distribution Panel is supplied with UL or CUL labels. They are engineered, assembled and tested at our factory to your specifications, and then are shipped to the customer's site ready for installation. The net result is a completely self-contained, easy to order, and easy to install fused power distribution panel meeting OSHA and NEC electrical standards.

Product News Bulletin

Change to Panelboard Configuration
Sep 29 2008

VTI standardized on using Square D panelboards in our Unitized Distribution Substations (UDSs) and the Fused Distribution Panels (FDPs) back in the 1980s. Please be advised that Square D is discontinuing the type NQOD panelboard. The new panelboard will be Square D’s type NQ.

The type NQ panelboard is functionally interchangeable with NQOD and will use all of the same branch circuit breakers. The most significant change in the new type NQ panelboard is the number of pole spaces available on the 100 amp single phase and the 100 amp 3 phase panelboards. Square D is offering only 18 circuits and 30 circuits in the 100 amp configuration of the NQ panelboard.

For VTI products this change will only affect the Fused Distribution Panels. The 20 circuit single phase FDP and the 24 circuit 3 phase FDPs will no longer be available. Both the single phase and the 3 phase panelboards will now be 18 circuits. If 18 circuits are insufficient for your requirements then use the 30 circuit panelboard and VTI will only populate the number of circuits you require.

Please contact VTI if you need clarification or have any questions.

FDP Design Guide

Our online Design Guides allow you to configure our products to your specifications, and instantly generate a written Quote, including pricing. Registration for this service is easy and free.
Find out more...


Typical applications include power distribution from an uninterruptable power supply, where standard thermomagnetic breakers are too slow to coordinate with the automatic transfer bypass circuit in a UPS. During a branch circuit fault, the UPS transfers back to the utility source to clear the fault. After the fault is cleared, the UPS transfers back to the UPS output. This transfer takes place because the UPS has limited short circuit capacity and cannot produce enough short circuit current to cause an ordinary branch breaker to reach its instantaneous trip level. On occasion you can drop the load during the transfer cycle or worse case, have the UPS transfer to the utility voltage source that is not there. The solution is to incorporate the Fused Distribution Panel (FDP) into your system network. Select the proper high-speed fuse with appropriate clearing time curve and current rating (from 0.1A to 30A).

The FDP is also useful for power distrubution to multiple small electrical loads such as electronic instruments, where fuses can be sized down to 0.1Amps for precise load protection for sensitive instruments. This offers an advantage over a standard panelboard where the smallest breaker is 10 Amps).

The FDP-DC is also available for DC power applications.


Industrial grade, 14-gauge steel with gray enamel finish, providing:
  • Access to switches and fuse holder through hinged door secured by quarter turn door fasteners.
  • Extra large wiring gutters for field terminations, accessed through removable trim panel.
  • Removable covers on top and bottom for load connections
  • NEMA 1 standard (also available in NEMA 3, 4, 4X and 12 enclosures) [NEMA Enclosure definitions]
Branch Circuit Switch
30 amp
Circuit Protection
Each branch switch output feeds a high-speed, current-limiting sub-cycle clearing fuse which in turn feeds the load. Neon lights on each output to indicate blown fuses are optional
Fuse Compatibility
Fuse holders for NEC Midget Style Fuses(13/32" x 1-½" (10x38mm), i.e. Ferraz-Shawmut Type A15QS or Bussmann Type KTK)
Circuit Indicators
Neon Blown Fuse Indicators (Optional) ("ON" when fuse is blown)
Incoming Line Protection
One of:
  • Main Breaker (MB) A molded case main circuit breaker sized to the load requirements.
  • Fused Disconnect (FD) A molded case breaker sized for panelboard rating with high speed fuses sized to coordinate with power source and load requirements.
  • Main Lug Only (MLO) No disconnecting device in the incoming line feeder.


Fused Distribution Panels can use either a molded case circuit breaker (MB Series) or a fused disconnect switch (FD Series) as the main secondary protection device. The FDP is also available with a Main Lug Only disconnect option (MLO Series).

Optional neon indicator lights on each output will indicate blown fuses.

All of our fused power distribution panels can be configured from the following options:

Main Disconnect:
  • Molded-case circuit breaker (MB)
  • Fused disconnect switch (FD) - high-speed current-limiting fuses in series with the Main Breaker
  • Main Lug Only (MLO)
Power Input:
  • 240/120V single phase
  • 120V 2-wire single phase
  • 208/120V three phase 4-wire
Branch Switches:
  • single pole for 120V circuits
  • double pole for 208 or 240V circuits
  • three pole for 3-phase 208V circuits
  • NEMA 1 (standard)
  • NEMA 3, 4, 4X and 12 also available
Optional Features:
  • Neon Blown Fuse Indicator Lights (BFI)
  • All-copper bus, lugs and neutral (ACU)
  • Bolt-on circuit breakers (BON)
  • Isolated Ground Bus - Aluminum (IGB) or Copper (IGBCU)
Number of Poles and Main Disconnect Current Rating:
  Input Voltage
  1Ø 120V 2 wire 1Ø 240/120V 3Ø 208/120V
No. of Poles 18 30 42 18 30 42 18 30 42
Max. Breaker/
Fuse Size
100 225 225 100 225 225 100 225 225

Note: DC Voltages are also available for 24V, 48V, or 125V units. More Details...


Front view door closed
Front view door closed
Angle view door closed
Angle view door closed
Mounted installation
Mounted installation
Door open
Door open
view of fuse holders & circuit breaker lockout kit
view of fuse holders & circuit breaker lockout kit
Trim panel removed showing internal view
Trim panel removed showing internal view
wide view with panel removed
wide view with panel removed
Internal view of 20 circuit main lug only panel
Internal view of 20 circuit main lug only panel
Front panel of FDP with blown fuse indicators and circuit breaker lockout kit installed
Front panel of FDP with blown fuse indicators and circuit breaker lockout kit installed
Top Entry FDP Panel closed.
Top Entry FDP Panel closed.
Top Entry panel open
Top Entry panel open
Top Entry Panel with the trim panel removed
Top Entry Panel with the trim panel removed
Bottom Entry panel closed
Bottom Entry panel closed
Bottom Entry panel open
Bottom Entry panel open
Bottom Entry panel with trim panel removed
Bottom Entry panel with trim panel removed


The following materials are available:

Ordering Information:

VTI can custom build FDP units to your requirements for type and number of fuses, circuit breaker ratings, and input power. We recommend our online FDP Design Guide, which will allow you to configure FDP units to your specific needs, and automatically generate a Quotation for one or more units, including pricing. Registration for this service is easy and free, and includes access to Design Guides for our other products as well.

You are also welcome to contact VTI directly via email or phone with questions or to discuss specific requirements or to order FDP units.

FDP Model Number Construction Guide

VTI uses a systematic method to construct descriptive Model Numbers for the Fused Distribution Panel. These model numbers include complete specifications on any unit and are suitable for inclusion in your Request for Quote, Project Plan or other documents. To build a model number for a Fused Distribution Panel, please use the following guide:

FDP-[disconnect][size (A)]-[phase][volts]-[# circuits]/[optionlist]

where the components of the model number include:
disconnect type FD (Fused Disconnect)
MB (Main Breaker)
MLO (Main Lug Only - on disconnect)
main disconnect size (Amps)
FD: indicate required main fuse rating (e.g., 100A)
MB: indicate required main breaker rating (e.g., 100A)
MLO: indicate Main Bus Bar rating: 100, or 225 Amp *
phase 1 Phase or 3 Phase
voltage 1Ø : 120 or 240 Volt
3Ø : 208 Volt
# circuits 18, 30 or 42 Circuit
note: larger panelboards available by request, please contact factory.
optionlist separated with commas, any of:
BFI (Blown Fuse Indicator lights)
BON (Bolt-on Branch Circuit Breakers)
ACU (All-copper Bus, Lugs and Neutral)
GBCU (Copper Ground Bus)
IGB (Isolated Aluminum Ground Bus)
IGBCU (Isolated Copper Ground Bus)
CP (Copper Panelboard Bus)
BE (Bottom Entry)
3R (NEMA 3R Weather-proof Enclosure)
4X (NEMA 4 Stainless-steel Enclosure)
NEMA12 (NEMA 12 Enclosure)
* Note:
30 circuit MLO panels are available in 100A or 225A Main Bus
18 circuit MLO panels are available in 100A Main Bus only
42 circuit MLO panels are available in 225A Main Bus only

a 3 phase, 208V FDP with a 60A Main Breaker and 42 Branch Circuits, and including the Blown Fuse Indicator lights and Copper Ground Bus, would have the model number:


Panel Schedule: To complete any order, please provide a panel schedule to specify the Amp rating and number of Circuit Breakers and Fuses. One can be downloaded from this page under the "Documents" section above.

Please note that our online Fused Distribution Panel Design Guide will automatically generate model numbers for you, as well as provide a written Quotation for any number of units, including pricing. You are welcome to Register for VTI Technical Services now to use this service. You will then have access to the FDP Design Guide as well as Design Guides for other products.


typical dimensions
Dimensional Diagram of typical configuration
[click for more detail]
Enclosure Dimensions
Voltage Poles Breaker/Fuse Size Dimensions
Weight (lbs)
1 240/120 18 60A 32"/34.5" 90
1 240/120 30 150A 42"/44.5" 110
1 240/120 42 225A 42"/44.5" 110
3 208/120 18 60A 32"/34.5" 90
3 208/120 30 100A 42"/44.5" 110
3 208/120 42 150A 42"/44.5" 110
VTI · P.O. Box 9086 · 24 McMillan Way · Newark, DE 19714 · USA
Phone: (302) 738 0500 · Fax: (302) 738 6594

sales   |   webmaster
Privacy Policy / Terms of Use © 2001-2008 VTI.