Explosion-Proof Distribution Boxes

Distribution and control enclosures that house breakers, starters and terminals inside a certified flameproof or increased-safety housing.

Typical range

Lighting distribution box with MCB rails
Power distribution enclosure with isolator
Control and motor starter enclosure
Custom panel builds to drawing

Indicative specification

Protection: Ex d IIC T6 / Ex e
Ingress protection: IP66
Rated voltage: AC 220 / 380 / 400 V
Materials: die-cast or welded aluminium, stainless steel
Ambient: -40 to +55 °C

Applications

Process units, compressor houses, pump stations, tank farms and offshore modules.

Part of the explosion-proof electrical apparatus range. Request a quote with your single-line diagram.

What actually goes inside a hazardous-area distribution box

An explosion-proof distribution box is an assembly, not just an enclosure. The certificate covers a certified housing; what the panel builder puts inside it — breakers, starters, terminal rails, isolators — determines whether the finished box still meets the marking on its label. That is why the single-line diagram, not the enclosure size, is the document we ask for first.

How to specify a distribution box

Voltage and system. Our panels are built for AC 220 / 380 / 400 V systems; state the frequency and the earthing arrangement.
Protection concept. Ex d IIC T6 for enclosures that contain switching devices; Ex e for enclosures that mainly distribute and terminate.
Ingress protection. IP66 is standard across the range — appropriate for outdoor, wash-down and dusty locations.
Incoming and outgoing ways. Number of ways, rating of each device, and whether an incoming isolator is required.
Material. Die-cast or welded aluminium for most industrial sites; stainless steel where corrosion or wash-down drives the decision.
Ambient and installation. The standard range is rated −40 to +55 °C; say if the box will sit in direct sun, in a compressor house or on an offshore module.

Which of the four builds do you need?

Build	Typical content	Usually specified for
Lighting distribution box	MCB rails feeding lighting circuits	Plant-wide lighting circuits grouped by area, so a fault trips one zone instead of the whole site
Power distribution enclosure	Incoming isolator and outgoing ways	Local power distribution in process units, pump stations and tank farms
Control and motor starter enclosure	Starters and control devices	Compressor houses and remote pump or fan stations
Custom panel build	Built to drawing	Offshore modules and retrofit projects where the available space fixes the shape

Ask for the marking, not just the enclosure. Two boxes can share a catalogue size while carrying different Ex markings. When the panel is complete, the marking has to cover the whole assembly, including the devices inside it.

Design decisions that change price and lead time

Most of the cost of a distribution box is decided before the enclosure is chosen. The number of outgoing ways, the rating of the incoming device, whether an isolator is interlocked with the door, and whether the cable entries are on the bottom face or split across two faces all move the build from a catalogue item to a project item. Sending the single-line diagram together with the cable schedule lets us confirm the arrangement in one step instead of three.

For process units, compressor houses, pump stations, tank farms and offshore modules, the enclosure is normally specified together with the area classification drawing. If you tell us the zone and the group, we can confirm which marking the assembly has to carry before any device is selected.

Frequently asked questions

Can we install our own breakers inside your enclosure?

Only components that are covered by the certification may be installed, and the finished assembly has to keep the marking valid. Tell us which devices you intend to use and we will confirm whether they can be fitted as supplied or whether the build has to come from us.

Is a distribution box the same as a junction box?

No. A junction box terminates and loops conductors; a distribution box contains protective or switching devices. They are often mounted side by side, but the certification argument is different for each.

Why does the single-line diagram matter so much?

It fixes the ways, the ratings and the interlocks. Without it, any quotation is only an enclosure price, and the difference usually appears later as a change order.

Do you build to a drawing where the space is fixed?

Yes. Retrofits on existing structures and offshore modules are usually built to drawing, because the entry positions and the mounting centres are already fixed by the steelwork.

What about the cable entries?

Entries are agreed with the build: count, size, thread standard and face. They must be closed with certified fittings, and unused ways need certified stopping plugs.

What to send us for a quote

Single-line diagram or a list of ways with ratings
Voltage, frequency and zone / gas group
Enclosure material and required IP rating
Cable entry count, sizes and thread standard
Quantity and site location

Request a quote with the diagram attached and we will return an indicative specification.

See how Ex enclosures are produced in our factory and product videos — from aluminium die-casting to final assembly.

Explosion-Proof Distribution Boxes: Frequently Asked Questions

How hazardous-area distribution boards differ from junction boxes, and what to specify with them.

What is the difference between a junction box and a distribution box?

A junction box terminates and splices conductors: it has terminals but no protective or switching devices, so it never intentionally breaks a circuit. A distribution box contains the protective and switching devices themselves, circuit breakers, isolators, contactors, indicators, and distributes power to several outgoing circuits. That difference drives the protection concept, because the switching devices create the arcing risk the enclosure has to handle.

Can I use my own preferred breaker brand inside the enclosure?

In most cases yes. We build the Ex rated enclosure around the device family you already standardise on, and the internal layout is confirmed against the breaker dimensions and the required cable entry positions before production. What must be checked together is the ambient temperature, the device rating and the enclosure volume, because the combination determines the maximum permissible dissipation inside the box.

How many outgoing circuits can a distribution box carry?

It depends on the incoming rating, the outgoing device sizes and the terminal capacity you need, which is why we size the enclosure from your single-line diagram rather than from a stock list. Send the diagram or a table of incoming and outgoing circuits and we will return the enclosure size, entry layout and terminal arrangement.

Is a hazardous-area distribution box more complex to certify than a junction box?

Yes, and for a good reason: when switching and protective devices are enclosed for use in Zone 1, the assembly as a whole has to satisfy the flameproof or increased-safety requirements, not just the empty box. That is why we ask for the full device list up front, and why we will tell you clearly when a device combination needs a different protection concept or a separate enclosure.

Question not answered here? Send it to our engineering team — we answer hazardous-area selection questions with the relevant standard referenced.