If you’ve ever seen “IP55” or “IP66” on an EV cable spec sheet and wondered what those two numbers actually mean, you’re not alone. The IP code (short for Ingress Protection) is a two-digit shorthand governed by IEC 60529. The first digit tells you how well a product resists solid particles like dust and grit; the second tells you how well it resists water. For an EV cable used outdoors in the UK, both digits matter, and the minimum you should accept is IP55.
What the two digits mean: a plain-English decode
Ingress Protection ratings are defined by IEC 60529 (Degrees of protection provided by enclosures). The format is always “IP” followed by two digits. If you see an “X” in place of either digit, it simply means that aspect was not tested, not that protection is absent. “IPX5” means tested against water jets but not rated for solids; “IP5X” means rated for dust but not specifically tested for water.
- FIRST DIGIT (Solids):
- 0 = No protection
- 1 = Protected against objects >50mm (e.g. back of hand)
- 2 = Protected against objects >12.5mm (e.g. fingers)
- 3 = Protected against objects >2.5mm (tools, wires)
- 4 = Protected against objects >1mm (small wires, nails)
- 5 = Dust-protected, no harmful deposits (most EV cables)
- 6 = Dust-tight, total protection
- SECOND DIGIT (Liquids):
- 0 = No protection
- 1 = Dripping water (vertical only)
- 2 = Dripping water up to 15° tilt
- 3 = Spray water up to 60° from vertical
- 4 = Splashing water from any direction
- 5 = Low-pressure water jets from any direction ← used on most portable EV cables
- 6 = Strong water jets from any direction ← used on outdoor EV sockets
- 7 = Immersion up to 1m for 30 minutes
- 8 = Immersion beyond 1m (manufacturer-specified)
- HIGHLIGHT: IP55 row and IP66 row in brand colour
First digit: solids protection (0-6)
The first digit is about solids: dust, grit, particles. The scale runs from 0 (no protection at all) to 6 (completely dust-tight). Most portable EV charging cables carry a first digit of 5, which means dust-protected: enough protection to prevent any deposit that would interfere with the cable’s operation, but not the hermetic dust-tight seal of a 6. For a cable used on a typical driveway, gravel path or car park, a 5 is entirely adequate.
Second digit: liquids protection (0-9)
The second digit is about liquids, specifically water. The scale runs from 0 (no protection) up to 9K (high-pressure steam jets, used in food industry wash-down). For EV cables, the meaningful range is 4-7:
- 4 (splash from any direction), adequate for covered parking only
- 5 (low-pressure water jets from any direction), the minimum for outdoor use, rain and drizzle
- 6 (strong water jets from any direction), better for fully exposed outdoor installations
- 7 (immersion to 1m for 30 minutes), required if the cable might be submerged
The testing for digit 5 involves a 12.5 litre-per-minute jet of water at 30kPa pressure from any direction. UK rain, even at its most persistent, is far less forceful than this. An IP55 cable has been tested to conditions significantly more demanding than a British autumn.
Which IP rating do you actually need?
Indoor charging (garage, carport): IP44 minimum
If your cable is stored inside and used in a dry garage or covered carport where it is never directly rained on, IP44 is a workable minimum. IP44 means protection against solid objects larger than 1mm and against water splashed from any direction. The limitation is that IP44 does not cover sustained rain on an uncovered drive.
Outdoor charging on a driveway: IP55 minimum
For any outdoor use (open driveway, street parking, uncovered car park), IP55 is the floor. BS 7671:2018+A2:2022 Section 722 references IP66 for fixed outdoor EV sockets because a fixed socket is always exposed; for a portable cable that you can bring inside when not in use, IP55 is the accepted working standard. Every cable we stock for outdoor use is rated at minimum IP55.
Connector caps and their own IP rating
This is a detail competitors consistently miss: the dust cap that covers the vehicle-side connector when it is not in use has its own IP rating, which may differ from the cable body. A well-specified cap provides at least IP55 protection to the idle connector, keeping rain, grit and debris out of the pin cavities when the cable is not connected to the car. Check the cap specification separately when assessing your cable’s outdoor storage capability. If the cable came without a cap, or the cap is damaged, a replacement EV charging accessory is worth adding.
IP55 vs IP66: what’s the practical difference?
IP55 handles rain. IP66 handles a pressure washer. In practice, the difference matters mainly for the fixed outdoor socket or wallbox mounted on the exterior of your house, not the portable cable.
A fixed outdoor socket at IP66 can withstand a powerful jet of water, the kind you might accidentally direct at it when cleaning the car or driveway. For the portable cable, IP66 gives added protection if the cable will live permanently outdoors through a full UK winter rather than being brought in after each charge. If you charge regularly on an exposed street with the cable coiled on a wet pavement, IP66 is a better choice.
- Charging location | Minimum IP rating | Why
- Dry garage / covered carport (cable stored indoors) | IP44 | Never directly rained on
- Open driveway, cable brought in after charging | IP55 | Rain & low-pressure jets from any direction
- Exposed street / cable left coiled on wet pavement | IP66 | Strong jets, permanent winter exposure
- Fixed outdoor socket or wallbox (always exposed) | IP66 | BS 7671 Section 722 references IP66 for fixed outdoor equipment
- Connector dust cap (idle connector) | IP55 min | Keeps grit & rain out of pin cavity between charges
- HIGHLIGHT: IP55 row (the everyday default) in brand colour
An outdoor EV charging socket should target IP66 as a matter of course. See our guide to outdoor EV charging sockets for what to look for in a permanently mounted unit.
The submersion myth: what IP67 and IP68 do NOT mean for EV cables
You may occasionally see an EV accessory rated to IP67 or IP68, and assume these are simply “better” versions of IP55. In one sense they are: a higher second digit means greater water protection. But IP67 and IP68 mean full immersion tolerance, not improved rain resistance. A product rated IP55 is not “almost” submersion-proof; it is rated for a completely different type of exposure.
This matters because EV charging cables are not designed to be submerged, and should not be left where they could be. The IP55 rating on a cable means rain, drizzle and careful wash-down are safe. It does not mean leaving the cable lying in a puddle, in a flooded driveway, or submerged in standing water. For more on what this means in practice, see our guide to leaving your EV cable out in the rain.
If you ever do find a cable has been submerged (during flooding, for example), retire it from service and arrange a replacement before using it again, even if the cable appears undamaged.
Does a higher IP rating affect charging performance?
No. IP rating has zero effect on charging speed, current capacity or power delivery. A 32A IP55 cable and a 32A IP66 cable will both deliver the same 7.4kW (single-phase, 32A) to your car. The IP number tells you only about the enclosure’s resistance to environmental ingress, not about the cable’s electrical specification.
The electrical specification is determined separately by the conductor cross-section (typically 2.5mm² for 16A cables and 6mm² for 32A cables), the contact resistance of the connector pins, and the current rating stamped on the plug. These are governed by IEC 62196-2, not by IEC 60529.
Frequently asked questions
What does the IP rating on an EV charging cable mean?
IP stands for Ingress Protection, defined by IEC 60529. It is a two-digit code: the first digit rates protection against solid particles (dust, grit) on a scale of 0-6; the second digit rates protection against liquids (water) on a scale of 0-9. A cable marked IP55 is dust-protected and resistant to low-pressure water jets from any direction.
What is the minimum IP rating for an EV cable used outdoors?
IP55 is the accepted minimum for a portable EV charging cable used outdoors in the UK. The second-digit 5 covers rain, drizzle and light snow. If your cable will be left fully exposed year-round rather than brought indoors between charges, IP66 provides additional protection against stronger water jets.
Is my IP55 cable safe to use in heavy rain?
Yes. Heavy UK rain falls well within the protection that the second digit 5 provides: the test condition is a 12.5-litre-per-minute jet at 30kPa, which is far more intense than rainfall. The cable body, connectors and the vehicle inlet are all sealed when connected.
Does IP55 mean my cable is waterproof?
Not in the full sense. IP55 covers water jets but not immersion. Do not leave connectors sitting in standing water or deliberately submerge the cable. For immersion-level protection you would need IP67 or IP68, but EV cables are not typically rated to these levels and should not be submerged regardless.
Do connector caps have their own IP rating?
Yes. The dust cap that covers the idle connector end has its own IP rating, which may differ from the cable body. A good quality cap provides at least IP55 protection to the connector. Check the cap specification separately. It is often overlooked when comparing cables.
Does a higher IP rating mean the cable charges faster?
No. IP rating measures environmental protection only. Charging speed depends on the cable’s current rating (16A or 32A), conductor cross-section and your car’s onboard charger capacity, none of which are related to IP.
