Why is 16.2 kg called a combination that should not occur?

Answer: It is 2.2 kg of shell plus a 14 kg load, or 159 N on one hand. A 5 kg tray and a 9 kg layer bring the heaviest lift to 11.2 kg.

Is IP54 enough on site?

Answer: For the shell of an electrician/plumber portable plastic tool box it is. IP54 covers dust and splashes and claims nothing about immersion.

Where does the 300 N handle figure come from?

Answer: 159 N static at 16.2 kg, times 1.9, rechecked at 240 N for 60 °C and rounded to 300 N.

Electrician/plumber portable plastic tool box

Q: Why does an electrician/plumber portable plastic tool box open to 100°?

Answer: At 90° the lid cannot stand and falls back at a touch. At 100° its centre of gravity sits 55 mm behind the hinge, so it rests on the stops, clear of the door swing.

Quick answer: An electrician/plumber portable plastic tool box is sized by its tightest position: 420 × 320 × 180 mm, 2.2 kg empty, a 100° lid, a 300 N handle.

Three work positions, one shell
Flat in front of the panel: 100° and the door swing
Upright in a shaft: 300 N against 16.2 kg
Above the ceiling: one hand on the lid, 5 kg tray
1.0 m drop, IP54 and −15 °C to 60 °C
FAQ

1. Three work positions, one shell

The same electrician/plumber portable plastic tool box stands flat at a distribution board, upright in a riser shaft and level above a ceiling. The three postures pull the design apart: flat needs a self-standing lid, upright a handle that takes the load, overhead low weight and one free hand.

The shell is 420 × 320 × 180 mm outside, 380 × 280 × 145 mm inside, 3.0 mm wall, 2.2 kg empty. Those figures were worked back from the narrowest position: a shaft is often 700 mm clear, so a 420 mm side still turns and 50 mm more would rub the wall.

Table 1: What each position asks of the shell

Work position	Lid and placing constraint	Shell value
At a board	Flat, lid clear of the door	100°, 420 × 320 mm footprint
In a shaft	Upright in one hand, 700 mm clear	420 mm side, 300 N handle
Above a ceiling	One hand free, 450 × 450 mm hatch	2.2 kg empty, 200 N latches

2. Flat in front of the panel: 100° and the door swing

An open board door sweeps 800 mm. An electrician/plumber portable plastic tool box set inside that arc has a problem at 90°: the lid stands on the vertical and comes back at the first knock, onto the back of a hand. The opening angle is set at 100° so the lid passes vertical by 10°.

Electrician/plumber portable plastic tool box in black open from above, egg-crate lid foam, six die-cut compartments, twin latches and a pressure valve

Passing vertical moves the centre of gravity. The lid is 320 mm wide, and at 100° its outer edge sits about 55 mm behind the hinge line, so the mass is on the far side and the lid rests on two 20 mm stops moulded with the body.

The cost is headroom: at 100° the highest point is 495 mm off the floor, and a board often sits 600 mm up, so the case is shut before it goes under.

3. Upright in a shaft: 300 N against 16.2 kg

A shaft has no floor to work on, so the electrician/plumber portable plastic tool box stands on its 420 × 180 mm face, handle up. The wall then takes the side load of a 14 kg load, and 3.0 mm of wall plus four lid ribs keeps a knee from pushing it out of shape.

One handle, designed for 300 N. A 16.2 kg total on one hand is a static 159 N, so 300 N is a factor of 1.9, covering the dynamic load of walking rather than inviting more weight.

That is where the contradiction sits: 16.2 kg should not occur. Sites fill 14 kg and carry it up three flights by the handle, loading wrist and seat together. Two layers fix it: a 5 kg tray out first, then 9 kg in the body, so the heaviest lift is 11.2 kg.

Table 2: Load path when carried upright

Part	How it carries	Design and actual
Handle	One, moulded with the lid	300 N design, 159 N static
Handle root	2 mm fillet	Intact after a 1.0 m drop
Wall	3.0 mm, four lid ribs	No bow under side load

4. Above the ceiling: one hand on the lid, 5 kg tray

Hatches are often 450 × 450 mm, so the 420 mm side goes through on the diagonal and the 320 mm side goes straight. One hand holds on, one works the lid, so the electrician/plumber portable plastic tool box needs draw latches a finger can trip: 200 N of hold is about 25 N to open.

Electrician/plumber portable plastic tool box, six black shells with orange handles in a studio, the largest open showing egg-crate foam and shallow trays

The upper tray of the electrician/plumber portable plastic tool box is rated 5 kg on four hooks at 30 N each against an actual 12 N, a factor of 2.4. With the tray out, 9 kg stays in the body, which is 11.2 kg and still steady on one hand.

5. 1.0 m drop, IP54 and −15 °C to 60 °C

The drop is 1.0 m at 16.2 kg, once on each of six faces. No latch may release, the tray must stay on its hooks, and the joint must open no more than 1.5 mm. A step-stool drop rarely clears 1.0 m, so this covers a mid-ladder slip.

IP54 on an electrician/plumber portable plastic tool box is two numbers: class 5 for dust, where ingress does not stop the box working, and class 4 for splashes. A 5 mm single-lip EPDM gasket at 20% compression handles splash without latch force climbing into the IP67 band.

The −15 °C to 60 °C band is where the PP shell works, 60 °C covering a summer van and a ceiling void. At the top end the modulus falls to six tenths, so the 300 N handle is rechecked at 240 N.

Table 3: Environmental and mechanical values

Item	Condition	Criterion
Drop	1.0 m, 16.2 kg, six faces	No release, gap ≤ 1.5 mm
High temperature	4 h at 60 °C	Handle hold ≥ 240 N
Low temperature	4 h at −15 °C	Latch opens with one finger

Conclusion

An electrician/plumber portable plastic tool box is sized by its tightest position, not by how many tools fit: 420 × 320 × 180 mm clears a 450 × 450 mm hatch and still turns in a 700 mm shaft, and a 100° lid stands by itself at a board. With 2.2 kg empty and a 14 kg load, the 16.2 kg total is split into two lifts, which is what gives the 300 N handle its meaning.