The load class on a manhole cover is the test load it must carry without failing. Pick too low and the cover cracks under a truck; pick too high and you overpay for every chamber on the job.
What the class means
EN 124 groups covers and gratings by where they are installed. Each class is tested with a static load on the frame; the number after the letter is that load in kilonewtons. D400 means 400 kN — roughly 40 tonnes.
The six classes
| Class | Test load | Typical location |
|---|---|---|
| A15 | 15 kN | Pedestrian and cycle areas |
| B125 | 125 kN | Footways, car parks |
| C250 | 250 kN | Kerbside channels |
| D400 | 400 kN | Carriageways, city streets |
| E600 | 600 kN | Loading yards, docks |
The 0.5 m kerb rule
C250 covers may sit in the kerbside channel only up to 0.5 m into the carriageway. Anything further out, in parking lanes that trucks cross, or at junctions belongs in D400.
Iron, composite or plastic
Ductile iron covers every class up to F900 and is the default for roads. Composite covers (typically B125–D400) have no scrap value, so they make sense where theft is common. Plastic covers suit A15 landscaping and meter boxes.
What to write in the BOQ
State the class, clear opening, frame shape and height, hinge and locking, and any cast marking. “Manhole cover, ductile iron, EN 124 D400, Ø600 clear opening, round hinged, with anti-rattle gasket, marked [utility logo]” leaves nothing to guess.
Technical sales engineer, GON. Specifies drainage and road products for municipal and IFI-funded projects.