What the two digits mean, what each common rating actually protects against, the four things IP ratings do not cover, and condensation — the most overlooked cause of outdoor driver failure.
IP65 does not mean submersible and IP67 does not mean permanent underwater use. The real trap in outdoor selection is not the size of the number — it is the three things an IP rating never covers: condensation, UV and surge.
How to read the code
The two digits after IP cover two separate things. Do not add them and do not treat one as "better":
First digit: solids (0–6). 0 unprotected, 5 dust-protected (limited ingress, no effect on operation), 6 dust-tight
Second digit: water (0–9). 4 splashing from any direction, 5 water jets, 6 powerful jets, 7 temporary immersion, 8 continuous immersion under manufacturer-defined conditions
Left: how to read the code. Right: what an IP rating never tells you
Common ratings compared
Rating
What it really protects
Typical use
Note
IP20
Finger-safe, no water protection
Dry indoors: ceilings, coves, risers
Not for bathrooms, kitchens or balconies
IP44
Small solids plus splashing from any direction
Damp indoor areas, sheltered soffits
Splash-proof is not jet-proof — not for open rain
IP65
Dust-tight plus water jets
Outdoor walls, facades, signage, factories
Handles rain and washdown; not immersion
IP67
Dust-tight plus temporary immersion
In-ground, water features, pooling spots
Temporary and to a stated depth, not permanent underwater
What IP does not cover
This is where outdoor selection usually goes wrong — the IP tests only look at the ingress of solids and water. They say nothing about:
UV — housings chalk, embrittle and discolour in sun; ask about UV-resistant material
Condensation — moisture sealed inside condenses with temperature swing, and IP67 does not stop it
Corrosion — coastal salt mist and chemical environments need material choices beyond IP
Surge and lightning — induced surge on outdoor runs is a leading cause of driver death
Temperature — rooftops and light boxes run hot; check the operating range and derating curve
Four more things to check
Operating temperature range — inside a sealed light box or on a west-facing roof the enclosure can sit 20–30 °C above ambient; check the maximum case temperature (tc point)
Surge immunity — for long outdoor and overhead runs, look at differential and common-mode surge ratings and add an SPD at the front end where needed
Potting versus gaskets — fully potted construction is usually more stable than gasket-only, particularly in-ground or in damp locations
Mounting position and cooling — sealing for ingress protection costs convection; leave air space and do not pack a small enclosure full
Condensation: the hidden failure
An enclosure heats up in the sun by day and cools at night; moisture sealed inside condenses on the board — that water comes from within, and IP67 cannot stop it. It shows up as intermittent protection trips, falling insulation resistance and corroded terminals, and it tests perfectly normal during the day.
Prevent — prefer fully potted products so moisture cannot reach the circuit; mount high enough to avoid standing water
Mitigate — use enclosures with a breather vent so pressure and humidity equalise
Detail — point cable entries downward, use proper glands and a drip loop so water cannot track along the cable
Do not stop at "what IP is it". Ask what temperature range it covers, whether it is potted, what surge level it survives and whether the housing is UV-stable. Those four answers predict outdoor service life far better than the IP number.
Specifying an outdoor job? Tell us where it mounts, the ambient temperature and whether water can pool — we will pick the right protection class from 47 models. Contact →