Actually, there is a firehose rating. IPX8 is about as good as it gets. However, there is some wiggle room in that I've seen components to meet IPX7 but not IPX5 - the rating scale is not necessarily sequential.

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IP stands for "ingress protection". The following digits ('characteristic numerals') indicate conformity with the conditions summarized in the tables below. Where there is no protection rating with regard to one of the criteria, the digit is replaced with the letter X.




First digit

The First digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.

Level Object size protected against Effective against
0 — no protection against contact and ingress of objects
1 >50 mm any large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part
2 >12.5 mm
fingers or similar objects
3 >2.5 mm
tools, thick wires, etc.
4 >1 mm
most wires, screws, etc.
5 dust protected
ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact
6 dust tight
no ingress of dust; complete protection against contact





Second digit
Protection of the equipment inside the enclosure against harmful ingress of water.
Level Protected against Details
0 not protected —
1 dripping water
Dripping water (vertically falling drops) shall have no harmful effect.
2 dripping water when tilted up to 15°
Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position.
3 spraying water
Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.
4 splashing water
Water splashing against the enclosure from any direction shall have no harmful effect.
5 water jets
Water projected by a nozzle against enclosure from any direction shall have no harmful effects.
6 heavy seas
Water from heavy seas or projected in powerful jets shall not enter the enclosure in harmful quantities.
7 immersion up to 1 m
Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1 m of submersion).
8 immersion beyond 1 m
The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer.
NOTE: Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that produces no harmful effects.




Additional letters

The standard defines additional letters that can be appended to classify only the level of protection against access to hazardous parts by persons:
Level Protected against access to hazardous parts with
A back of hand
B finger
C tool
D wire

Further letters can be appended to provide additional information related to the protection of the device:
Letter Meaning
H high voltage device
M device moving during water test
S device standing still during water test
W weather conditions


Thanks Wikipedia.


Jake Kohl