20 ft or 40 ft Container for a Generator Set?

In Short

A 20 ft container suits smaller generator sets and simpler transport, while a 40 ft container gives room for larger sets, more fuel and more sound attenuation. The generator set and the site requirements decide which size is right, and sometimes a non-standard length or a high-cube version is the better answer.

A generator container is built around the set, not the other way round, but the two ISO lengths - 20 and 40 feet - decide a great deal: what fits inside, how quiet the package can be, how much fuel it carries, and how it travels. This guide explains what each size takes, where the high-cube version helps, and when a non-standard length is the better answer.

What Fits in Each Size

A 20 ft container takes small and medium generator sets with their service space, an air inlet and outlet path and a modest fuel tank. A 40 ft container takes large sets, or a medium set with long silencers, a large belly or day tank and switchgear at one end. The deciding dimension is usually not the set's length but the length that remains for the air path and the acoustic treatment.

The high-cube version is taller, which helps with the radiator, the exhaust silencer on the roof structure, cable trays and service access over a tall engine.

Air, Sound, Fuel and Switchgear

The air must enter, pass the set, be drawn through the radiator and leave; in an acoustic container the inlet and outlet carry silencers, and their length is what buys the quiet. A tight sound limit therefore pushes a set from a 20 ft into a 40 ft container, or moves the radiator out to the roof or beside the container. The fuel tank - as a base-frame belly tank or a separate day tank - competes for the same space, and so does a switchgear room with the breaker, the controls and the auxiliary panel at the container end.

Weight, Transport and Certification

A container travels by truck, rail and ship without special permits as long as it keeps ISO dimensions and its weight stays within the road and the container rules; corner castings let it be lifted with standard spreaders. When it is to be shipped as freight on a container ship, it needs a CSC safety approval plate. A heavy large set in a 40 ft container approaches the weight limits, so the set, the tank filling for transport and the structure are checked together.

Where neither size fits - a set that needs a longer box, a package that must be wider for service - a non-standard enclosure is built and moved as an oversize load. AXON builds 20 ft and 40 ft containers, standard and high cube, and custom enclosures around generator sets of any make; send the set, the sound limit, the fuel autonomy and the transport route, and the proposal shows the container that fits.

In short

20 ft: small and medium sets, modest silencers and tank
40 ft: large sets or long silencers, large tanks, switchgear room
High cube is taller: more room for radiator, exhaust and cable trays
The sound limit and the silencer length often decide the size
CSC plates for shipping as freight; weight limits checked with the set
Non-standard enclosures where neither size fits

What to send with an enquiry

Generator set make, model, dimensions and weight
Sound limit and distance
Fuel autonomy and whether the tank is inside
Switchgear and controls to be housed
Transport route and lifting on site
Site ambient, altitude and corrosion class

Send an enquiry Send us files

Questions we are often asked

What size generator fits in a 20 ft container?

Small and medium sets with their service space and a modest air path; the exact fit depends on the set, the sound target and the tank. Large sets need a 40 ft container.

Is a high cube container worth it?

Often, for large engines: the extra height helps the radiator, the exhaust and the service access. It is still an ISO size and travels like any container.

Does a generator container need CSC certification?

Only if it is to travel as freight on a container ship or by intermodal transport under the CSC convention. Containers moved only by truck to site often do not need it.

Can the fuel tank be inside the container?

Yes, as a belly tank under the set or a day tank, within the space and weight limits; larger autonomies use an external bulk tank.

Can a container be longer than 40 ft?

Yes, as a non-standard enclosure, but it then travels as an oversize load and does not stack with ISO containers.