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DP and DCB in FTTH Network : Precious Information

DP (Distribution Point Box) in FTTH : This article will cover the basic information of DP. what is DP in a FTTH network and why use DP. In this article I will also cover the DCB (distribution/connection box). You don't have to be confused about DP and DCB, DP and DCB have very close similarity. Read this article till the end, hope that full information will be given.

DP boxes shall be used to house terminal modules for cross-connections of secondary distribution cables and subscriber’s indoor cables/wires. The boxes shall be installed on walls inside building premises.

The distribution/connection box (DCB) shall be used either as a distribution point (DP) box for the secondary network or as a connection box for the customer's service wires. The DCB shall be installed outdoor at the customer's perimeter wall, either flushed or surface mounted. Now I will discuss in detail about DP and DCB.

detail explanation about DP and DCB
Distribution boxes in FTTH Network


Indoor Distribution Point Box

The metallic box which houses and protects the terminal blocks or modules and other hardware contained within the box. The box is installed inside building premises.

DP : Distribution Point

These are terminals which serve as an interface point for direct connections or cross-connection of secondary distribution cables and indoor cables/wires.

DP : Technical Requirements

The DP boxes shall be designed and constructed to be suitable for surface mounting installations.The DP box 30-pair terminal blocks shall be common for direct terminations of both the secondary cable and the customer's indoor cables/wires. Cross-connection is not required.

The DP boxes 50 and 100 pairs shall have cross-connection facilities for secondary cable and the customer's cables/wires. The DP box shall not have any sharp edges or other defects, which may be injurious to personnel or potentially damaging to other components and materials used with the box.

The DP housing shall be protected from the environment and protected against solid objects greater than 1 mm, and protected against direct sprays of water up to 15 degrees from the vertical. All materials used in the DP box shall be non-toxic and dermatologically safe.

DP Design Requirements 

The indoor distribution box shall be supplied in 3 types-
Type-1 : 30 pairs for the Maximum Secondary Pair Terminations. Type-1 application for direct termination of up to 30 pairs secondary cable and indoor cable/wires. No cross-connection is required.

Type-2 : 50 pairs For Maximum Secondary Pair Terminations .Type-2 application for the cross-connection of up to 50 pairs secondary cable and 50 pairs indoor.

Type-3 : 100 pairs For Maximum Secondary Pair Terminations. Type-2 application For cross-connection of up to 100 pairs secondary cable and 100 pairs indoor cable/wire.

The DP box shall be designed and have provisions for major components like- BASE PANEL, CABLE ENTRY HOLES,FIXING HOLES FOR MOUNTING,CABLE SUPPORT,BACKBOARD FOR FRAMES, COVER, DP LOCK, MOUNTING FRAMES, WIRE GUIDES, EARTHING TERMINAL, RUBBER GASKET/GROMMETS.

BASE PANE : Material used for base panel is Steel sheet. Base Panel of DP generally made-up of Steel sheet. Coating of metal surface by the high quality paint or epoxy resin. Wall thickness of DP approx 1.5 mm, minimum.

Outside dimensions of DP, Type 1 ( 30-Pair) width- 250 mm, height- 220 mm, depth- 110.
Outside dimensions of DP, Type 2 ( 50-Pair) width- 450 mm, height- 350 mm, depth- 110.
Outside dimensions of DP, Type 3 ( 100-Pair) width- 450 mm, height- 500 mm, depth- 110.

CABLE ENTRY HOLES : Cable entry holes details mentioned below-
Type 1 ( 30-Pair) : Two 40 mm diameter at top and bottom panels.
Type 2 ( 50-Pair) : Two 40 mm diameter at top and bottom panels.
Type 3 (100-Pair) : Two 50 mm diameter at top and bottom panels.

FIXING HOLES FOR MOUNTING : Four-5 mm diameter fixing holes.

CABLE SUPPORT : U-shaped steel plates opposite the entry holes, at top and bottom, to serve as hooks for Plastic Cable Ties.

BACKBOARD FOR FRAMES: Generally it is made-up of non-conductive material.

COVER : Generally material used for DP cover is Steel sheet . Wall thickness of DP cover approx 1.5 mm, minimum. 

Outside dimensions of DP Cover, Type 1 ( 30-Pair) width- 250 mm, height- 220 mm, depth- 15 mm.
Outside dimensions of DP Cover, Type 2 ( 50-Pair) width- 450 mm, height- 350 mm, depth- 15 mm.
Outside dimensions of DP Cover, Type 2 ( 50-Pair) width- 450 mm, height- 500 mm, depth- 15 mm.

HINGES: - Types 1, 2 and 3: Shall be fixed on the right side of cover/base. Cover shall swing from left to right to minimum 135° opening angle.

DP LOCK : Male, hexagonal-type, 12 mm between the flats.location for DP lock at middle left side of cover.

MOUNTING FRAMES: Material used for mounting frames is Stainless steel.Dimensions of frames is mentioned below in details-

Type 1 ( 30-Pair): Width-104.5 mm,  Height-92 mm, Depth-50 mm, Thickness- 1 mm,  Pitch- 35 mm.
Type 2 ( 50-Pair): Width-104.5 mm,  Height-160 mm, Depth-50 mm, Thickness- 1 mm,  Pitch- 35 mm.
Type 3 ( 100-Pair): Width-104.5 mm,  Height-335 mm, Depth-50 mm, Thickness- 1 mm,  Pitch- 35 mm.

WIRE GUIDES: Material used for wire guide is Stainless steel. For Type 1 (30-Pair) total of 4 wire guides placed 2 each on left and right side of mounting frame. For Types 2 and 3 (50 and 100-Pair) total of 9 wire guides placed 3 each on both sides and center of the box.

EARTHING TERMINAL: Type of earthing terminal used Screw-type, to accommodate 3 mm diameter earthing wire.It shall be fixed near the secondary cable entry hole.

RUBBER GASKET/GROMMETS: Material used for rubber gasket is Vulcanized rubber, Application for rubber gaskets between all mating surfaces, i.e., between cover and base and application for rubber grommets all cable entry holes. Grommets shall be 'push-thru' type.

Packing And Marking Of DP 

The indoor distribution point boxes shall be packed in individual boxes fully assembled. The packing shall be suitable to protect the DP boxes from damage during shipping by land, sea, and during storage.

The individual packages may be multi-packed to a maximum weight of 25 kg. The shipping cartons shall be of sufficient strength and durability to protect the contents from normal handling, storage and transportation.Each box shall contain full assembly instructions in English.

Marking on Each individual package and multi-packed carton shall be marked in legible color with the information in English, on at least two sides of the package/carton.

DCB Distribution/Connection Box 

Above I have already mentioned that the distribution/connection box (DCB) shall be used either as a distribution point (DP) box for the secondary network or as a connection box for the customer's service wires. The DCB shall be installed outdoor at the customer's perimeter wall, either flushed or surface mounted.

The DCB is intended for use in areas where the secondary distribution network are installed direct buried or in ducts and which overvoltage protection is not required.

If used as a distribution point box, the DCB shall contain one or two 10-pair terminal module for the terminations of maximum 20 secondary cable pairs and seven 4-pair buried service wires (BSW) on the network side, including the direct connection of the customer's service wire which is served directly by the box.

If used as a connection box, the DCB shall contain only one 10-pair terminal module for the interconnection of one or two 4-pair BSWs and the customer's service wires.

Detail description of DCB


The DCB is a non-metallic, wall-mounted box with inside dimensions of 160 (W) x 220 (H) x 80 mm (D). The box accommodates two 10-pair terminal modules. It is designed to fit into a wall opening of 180 width x 240 height x 80 mm depth, for flush-mounting installation.

Terminal Module: This is a 10-pair disconnection-type module, with a standard overall height of 21 mm. The module is used for the termination or connection of secondary cable pairs, BSWs, and the subscriber's indoor wires, via the insulation displacement connection (IDC) technique.

The DCB shall be designed and constructed to be suitable for outdoor installations, either flush-mounted or surface-mounted on concrete walls. For flush-mount applications, the DCB shall fit properly onto a wall opening of 180 width x 240 height x 80 mm depth.

The DCB shall be designed such that its cover shall protrude outside the surface of the opening and covers the outside perimeter around the wall opening, for flush-mount installations.The hinges of the DCB shall be designed such that the cover can be opened without hindrance to a minimum 105° turn, from left to right, for flush-mount installations.

The DCB shall be designed to allow removal and replacement of its cover for maintenance purposes. All components of the DCB shall be of high quality design, workmanship and finish. The box shall be free from flaws, pinholes, bubbles, cracks, inclusions, or other defects visible with the naked eye. The box shall exhibit a uniform finish both inside and outside.

The DCB shall be sturdy and impact-resistant against damage during placing or installation operations.The DCB shall be protected from the environment also protection against dust (no aggressive deposits), and protection against splashing water from all directions.

All plastics and rubber components of the DCB shall be inhibited against ultra-violet degradation due to direct sunlight exposure.The design of the DCB shall minimize weight and bulk. The overall appearance of the installed unit shall be reasonably aesthetically pleasing. All materials used in the DCB shall be non-toxic and dermatologically safe.

DCB Design Requirements


The DCB shall be designed and have provisions for major components,DCB BASE, CABLE ENTRY HOLES, FIXING HOLES FOR BOX, BRACKET-LOCK, DCB COVER, DCB HINGES, LOCKING SYSTEM, MOUNTING FRAME FOR MODULE, WIRE GUIDES, CLAMP, CABLE SUPPORT, RUBBER SEALS.

DCB BASE : Material used for DCB based is Glass fiber reinforced polyester or polycarbonate, minimum wall thickness is 3.2 mm. Inside dimensions of base is approx 160 Width x 220 Height x 80 mm Depth.

CABLE ENTRY HOLES : Two 35.5 mm diameter, at bottom of box.
FIXING HOLES FOR BOX : Four-5 mm diameter, at corners of box.
BRACKET-LOCK : Shall be fixed onto the base to mate with the lock.

DCB COVER : Material used for DCB cover is Glass fiber reinforced polyester or polycarbonate. Minimum wall thickness is 3.2 mm. Minimum Outside dimensions is 180 Width x 240 Height x 15 mm Depth. Door swing- From left to right. Opening angle shall be 105°, minimum.

DCB HINGES : Hinge shall allow removal and replacement of the cover.

LOCKING SYSTEM : Locking system material is Non-corrosive steel. Lock and key type is hexagonal-type, 12 mm between the flats, 14 mm deep.

MOUNTING FRAME FOR MODULE : Material used Stainless steel for the mounting frame for module. It shall accommodate two 10-pair IDC disconnection-type modules. The modules shall clip onto the mounting frame.

WIRE GUIDES : Material used for wire guides Rigid plastic of high quality. Size of wire guide used is 25 mm inside diameter.

CLAMP, CABLE SUPPORT : Clamps shall secure 2 wire bundles of 9 mm diameters alternative solution is brackets to support plastic cable ties and cables.

RUBBER SEALS : Material used for rubber seal is Vulcanized rubber. GASKETS shall be provided between all mating surfaces. GROMMET OR SEALING PLUG shall be provided in cable entry holes.

Packing And Marking Of DCB

All components/parts for the DCB, as described in this specification, shall be provided and packaged as a complete assembled unit.Any auxiliary components or accessories not described in this specification, e.g., fixing screws and plastic tightening plugs, shall also be included in each package.

The DCB unit shall be covered with a protective material to prevent scratching or damage during shipping or storage, prior to placing the unit into the packaging carton.The individual DCB packages may be multi-packed in strong, weather resistant carton boxes suitable for shipping, handling and storage. The weight of each multi-packed carton shall not exceed 25 kg.

Each individual package and multi-packed carton shall be marked in legible color with the information in English, on at least two sides of the package and the multi-packed carton box.


Last Word

I have tried to give full information about DP and DCB.I hope you will be satisfied with the information given by me. If you all liked this article "DP and DCB in FTTH Network", then like and share.Stay connected with us to get similar information.

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