Passivelysafe roadside cabinets forelectrical equipment
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PASSIVE SAFETY Passively safe roadside cabinets for electrical equipment By David Milne INTRODUCTION Signs and lighting columns now being installed on trunk roads with- out barriers are now usually passively safe to EN 12767:2007 - "Passive safety of support structures for road equipment" . This passively safe street furniture is proving exceptionally safe with al- most no recorded severe injuries in vehicle impacts. Passively safe sign- .posts and lighting columns are prov- ing a most economical alternative to traditional steel signposts and light- ing columns with associated protec- tive barriers and energy absorbing terminals. This direct financial sav- ing explains why passive safety is proving so popular on our trunk roads. Regrettably rural non-trunk A roads with their serious accident rates are far behind in their use of passively safe street furniture. Until now crash tested passively safe roadside cabinets have been un- available. Cabinets on trunk roads have typically been either installed behind barriers, up embankments or otherwise safely clear of the carriage- way. Now Ritherdon have developed a cabinet which is passively safe to EN 12767. Ritherdon make high quality, long lasting, weatherproof, painted stainless steel cabinets for highway use. Their cabinets are used for feeder pillars for lighting column and to house electrical apparatus in- cluding traffic light controllers and motorway communication equip- ment. Cabinets are needed to pro- vide a dry accessible environment for the increasing amounts of electrical equipment on our roads. Ritherdon's use of stainless steel construction for their cabinets allows thinner mate- rial to be used without fear of corro- sion reducing weight and lessening impact forces thus making such con- struction well suited to the passively safe cabinet they have developed. Crash Testing Ritherdon's Pas- sively Safe Cabinet at the Trans- port Road Laboratory in accord- ance with BS EN 12767 "Passive safety of support structures for road equipment. Requirements, classification and test methods" Ritherdon crash tested their "RE800 Passive Cabinet" at TRL in December 2012 and January 2013. The cabinet was 800 wide 380mm deep and 1200 high and loaded with two weighted shelves each weighing 13.1 kg to represent the weight of electrical equipment. THE RITHERDON CABINET AND TRl CRASH TEST VEHICLE Two BS EN 12767 crash tests were conducted where cabinets were hit by 900 kg cars at 3S kph and 100 kph. In both tests the cabinet sheared away near its base on impact. In the tests the cabinet was knocked ahead of the vehicle in the impact and ended up down the track close to the path of the vehicle. The shear ar- rangement for mounting the cabinet to give the passive safety perform- ance has been developed and pat- ented by Ritherdon. The TRLtesting gave the cabinet a passive safety classification to BSEN 12767 of 100 NE 3. ELECTRICAL ISOLATION Electrical cables pose a problem for passively safe equipment in an im- pact. The National Annex to BSEN 12767 demands any electrical sup- ply is isolated in an impact to pre- vent apparatus becoming electri- cally live. Also cables must pull away and not tether the cabinet in any impact. Ritherdon sought Poletech's ex- pertise in electrical isolation systems gained from supplying cabling sys- tems to passively safe lighting col- umns and illuminated signs.The test cabinet was provided with 4 multi- core cables to represent a typical ca- bles arrangement. The cables were provided with moulded PolePlug IP 68 rated weatherproof plugs. The plugs separate at or below ground level when the cabinet is knocked forward during the impact. Impact will also trigger a shock sensor mounted in the cabinet which then isolates the power sup- ply at a relay safely safely sited away from the cabinet. The isolation arrangements worked perfectly in the test. New cabinets could have been readily in- stalled on the existing undamaged foundation units utilizing the plugs on the feeder cables. The Ritherdon Cabinet and TRL Crash Test Vehicle The car after a 100 kph crash test with the Ritherdon cabinet www.tecmagazine.com
Transcript of Passivelysafe roadside cabinets forelectrical equipment
PASSIVE SAFETY
Passively safe roadsidecabinets for electricalequipmentBy David Milne
INTRODUCTIONSigns and lighting columns nowbeing installed on trunk roads with-out barriers are now usually passivelysafe to EN 12767:2007 - "Passivesafety of support structures for roadequipment" .This passively safe street furniture
is proving exceptionally safe with al-most no recorded severe injuries invehicle impacts. Passively safe sign-.posts and lighting columns are prov-ing a most economical alternative totraditional steel signposts and light-ing columns with associated protec-tive barriers and energy absorbingterminals. This direct financial sav-ing explains why passive safety isproving so popular on our trunkroads. Regrettably rural non-trunk Aroads with their serious accidentrates are far behind in their use ofpassively safe street furniture.Until now crash tested passively
safe roadside cabinets have been un-available. Cabinets on trunk roadshave typically been either installedbehind barriers, up embankments orotherwise safely clear of the carriage-way. Now Ritherdon have developeda cabinet which is passively safe toEN 12767. Ritherdon make highquality, long lasting, weatherproof,painted stainless steel cabinets forhighway use. Their cabinets are usedfor feeder pillars for lighting columnand to house electrical apparatus in-cluding traffic light controllers andmotorway communication equip-ment. Cabinets are needed to pro-vide a dry accessible environment forthe increasing amounts of electricalequipment on our roads. Ritherdon'suse of stainless steel construction fortheir cabinets allows thinner mate-rial to be used without fear of corro-sion reducing weight and lesseningimpact forces thus making such con-struction well suited to the passivelysafe cabinet they have developed.
Crash Testing Ritherdon's Pas-sively Safe Cabinet at the Trans-port Road Laboratory in accord-ance with BS EN 12767 "Passivesafety of support structures forroad equipment. Requirements,classification and test methods"Ritherdon crash tested their
"RE800 Passive Cabinet" at TRL inDecember 2012 and January 2013.The cabinet was 800 wide 380mmdeep and 1200 high and loaded withtwo weighted shelves each weighing13.1 kg to represent the weight ofelectrical equipment.
THE RITHERDON CABINET AND TRlCRASH TEST VEHICLETwo BS EN 12767 crash tests wereconducted where cabinets were hit by900 kg cars at 3S kph and 100 kph.
In both tests the cabinet shearedaway near its base on impact. In thetests the cabinet was knocked aheadof the vehicle in the impact andended up down the track close to thepath of the vehicle. The shear ar-rangement for mounting the cabinetto give the passive safety perform-ance has been developed and pat-ented by Ritherdon.The TRLtesting gave the cabinet a
passive safety classification to BSEN12767 of 100 NE 3.
ELECTRICAL ISOLATIONElectrical cables pose a problem forpassively safe equipment in an im-pact. The National Annex to BSEN12767 demands any electrical sup-ply is isolated in an impact to pre-vent apparatus becoming electri-cally live. Also cables must pullaway and not tether the cabinet inany impact.Ritherdon sought Poletech's ex-
pertise in electrical isolation systemsgained from supplying cabling sys-tems to passively safe lighting col-umns and illuminated signs.The testcabinet was provided with 4 multi-core cables to represent a typical ca-bles arrangement. The cables wereprovided with moulded PolePlug IP68 rated weatherproof plugs. Theplugs separate at or below groundlevel when the cabinet is knockedforward during the impact.Impact will also trigger a shock
sensor mounted in the cabinetwhich then isolates the power sup-ply at a relay safely safely sited awayfrom the cabinet.The isolation arrangements
worked perfectly in the test. Newcabinets could have been readily in-stalled on the existing undamagedfoundation units utilizing the plugson the feeder cables.
The Ritherdon Cabinetand TRL Crash TestVehicle
The car after a 100 kphcrash test with theRitherdon cabinet
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PASSIVE SAFETY
Ritherdon found the Poletech expertise in ca-bling and electrical isolation married in so wellwith their all weather electrical cabinet businessthat they have now taken over the finn.
The combination of Poletech cabling tech-nology and the Riverdon shear failure mode atthe underside of the cabinet has the followingadvantages:a) The supply cables with their moulded
plugs and the buried cabinet base will al-most certainly be undamaged in a vehicleimpact so a replacement cabinet to bequickly installed (minimizing traffic delaysand traffic management during installa-tion)
b) Cabinets can be fully factory fitted outprior to installation. Cabinets can be re-turned to the factory for equipment up-grading and maintenance. This facilitates a"plug and play" approach to electrical in-stallations and their maintenance.
c) The cabling and cabinet below ground basecan be installed early in the contract andplated over. Cabinets containing the elec-trical equipment can then be quickly in-stalled after the civil works are completed
Inset: The plinth andcables after the 100
kph impact (thecables and underlying
cast-in foundationunit are totally
undamaged but thevisible plinth isdesigned to be
replaced).Main pic: The cabinet
after the 100 kphimpact showing the
separated "PolePlugs"
CONCLUSIONSThe concept of a "passively safe road" with onlypassively safe street furniture is a great conceptfor a road scheme and Ritherdon's new cabinetswill help make it achievable. Passive safety ad-vances have been nearly always product led andRitherdon's passively safe cabinets will continuethis pattern.
When passively safe street furniture began tobe widely used in the UK in 2003/2004 theproducts were Scandinavian. Now uk industry isdeveloping our own passively safe products.
Ritherdon aim to have a range passively safecabinets that are smaller and lighter than thecrash tested cabinet to create a family of pas-sively safe products meeting the requirementsof EN 12767.
If you are need to install electrical equipmentin a cabinet or cabinets for a road scheme wherethey would be vulnerable to vehicle impact youmay well find a passively safe cabinet providesthe cheapest and safest solution.
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