OUTDOOR ENCLOSURES for BACKFLOW …

1 Most of us would probably agree t hat t he most import ant benef it of above ground backf low prevent er ENCLOSURES is t he eliminat ion of underground vault s or pit s whichare def ined by OSHA as conf ined spaces. In t he case of t he reduced pressure principle backf low prevent er, adequat e drainage is provided so t hat t he public wat er supply is prot ect ed. Worker saf et y is great ly improved because t he above ground enclosure is not a conf ined space as def ined by OSHA. There are, however, st ill some saf et y issues that have not been addressed unt il recent er s used f or f reeze prot ect ion in ENCLOSURES are powered by elect ricit y. Becauseelect ricit y is so common in our everyday lives, it is of t en not t reated wit h t he respectthat it deserves. Current f low of 1/ 10 of an amp or 100 milliamps is enough t o st opthe heart and cause fibrillat ion.

2 To put t his in perspect ive, one 1 2 wat t light bulb draws1/ 10 amp on a 120 volt circuit . It's easy t o underst and t hat a small amount of elect ricit y t hrough t he heart can dangerous as elect ricit y is in dry locat ions, damp and wet locat ions dramat icallyincrease the danger. We have all heard t he saying t hat wat er and elect ricit y do not American Societ y of Sanit ary Engineering ( ASSE) has recent ly made t he decision that the interiors of backf low prevent er ENCLOSURES are damp locat ions as def ined in Art icle 100 of the National Electrical Code. The reason for this ruling is that water and ot her liquids can accumulat e in the int erior of an enclosure f rom several sources. So m e o f these are list ed below:1. Sprays of wat er f rom t est cocks during t est ing and/ or maint Leaks in t he piping or backf low Dischar g e f rom a reduced pressure principle backf low prevent er caused byline pressure f luct uat ions, f oreign mat erial in t he check valves, a rupt ured diaphragmin t he relief valve assembly or normal relief operat Condensat ion caused by t he piping and backf low assembly surf ace t emperat urebeing below t he dew point t emperat ure of t he surrounding Intrusion of rain wat er bet ween t he concret e slab and t he walls of t he enclosureand under and t hrough drain Dampness inherent in a concret e slab placed on t he ore, t o meet t he requirement s of t he Nat ional Elect rical Code f or damp locat ions.

3 Heat ers used in backf low prevent er ENCLOSURES must be constructed and installedaccording t o Art icle 424-12(b) of t he Nat ional Elect rical ENCLOSURES f or BACKFLOW PREVENT I ON A SSEMBLI ES a nd ELECRICA L HAZA RDSpage 1 Art icle 424-12(b) of the 1999 and 2002 Editions of the Nat ional Elect rical Code st at esthat: "Heaters and related equipment installed in damp or wet locat ions shall beapproved f or such locat ions and shall be constructed and installed so t hat wat er or ot her liquids cannot ent er or accumulat e in or on wired sect ions, elect rical component sor duct work."Drainage syst ems f or backf low prevent er ENCLOSURES are designed t o meet t he requirement s of ASSE St an d ar d # 1 0 6 0 , OUTDOOR ENCLOSURES f or BACKFLOW Prevent ionAssemblies. This St andard st ates t hat : " The dept h of water within the enclosureshall not exceed 1 50 mm (6 inches) during f ull f low of t he backf low prevent er reliefdischarge, nor shall t he dept h of wat er exceed 8 mm ( 5 inches) af t er complet ionof f ull flow.

4 " See Figure 1 liquid levelallowable by ASSE 10606"Figure 1 Heat er s inst alled inside t he ENCLOSURES more t han six inches above t he f loor must be liquid t ight and suit able for use in damp or wet locat ions t o meet t he constructionrequirement s of Art icle 424-12( b) of t he Nat ional Elect rical can be seen t hat any heat er mount ed less t han six inches above t he f loor level of an enclosure can be submersed. Submersion of t he heat er virt ually guarant ees t heent rance and accumulat ion of wat er or ot her liquids in or on wired sect ions and elect rical component s inside t he heat er. Theref ore, t o sat isf y t he installation requirement s of Art icle 424-12(b) heaters must be mounted more t han six inches above t he floor t o prevent t he ent rance of wat er or ot her liquids int o t he heat 2 CONCRET E SL A BFlo o r LevelArt icle 424-12(b) of the 1999 and 2002 Editions of the Nat ional Elect rical Code st at esthat: "Heaters and related equipment installed in damp or wet locat ions shall beapproved f or such locat ions and shall be constructed and installed so t hat wat er or ot her liquids cannot ent er or accumulat e in or on wired sect ions, elect rical component sor duct work.

5 "Drainage syst ems f or backf low prevent er ENCLOSURES are designed t o meet t he requirement s of ASSE St an d ar d # 1 0 6 0 , OUTDOOR ENCLOSURES f or BACKFLOW Prevent ionAssemblies. This St andard st ates t hat : " The dept h of water within the enclosureshall not exceed 1 50 mm (6 inches) during f ull f low of t he backf low prevent er reliefdischarge, nor shall t he dept h of wat er exceed 8 mm ( 5 inches) af t er complet ionof f ull flow." See Figure 1 liquid levelallowable by ASSE 10606"Figure 1 Heat er s t hat are suit able f or use in damp or wet locat ions have been t est ed by ETLor UL f or conditions f ound in t hose environment s. The name plat e on t he heat erwill bear the stat ement "for use in damp or wet locations " and t he ETL or UL markand cont rol number.

6 These heat ers are not t est ed f or or meant t o be immersed;theref ore, t hey should not be mount ed less t han six inches above t he f is also st rongly recommended t hat ground fault circuit int errupt ers are inst alledin t he heat er circuit s for addit ional prot ect ion. However, It should be warned t hat GFCI ' s d o not t ake t he place of t he requirement s of Art icle 424-12(b) of the National El e c t r i c a l Code. GFCI ' s a r e s u s cept ible t o damage by volt age surges f rom ut ilit y companies and light ning strikes and can cont inue t o deliver power when t hey no longer provide ground f ault prot ect ion. According t o OSHA: " Due to the complexity of a GFCI, it is necessary to test the device on a regular basis. For permanent ly wired devices, a mont hly t est is recommended.

7 GFCI ' s h a v e a built -in t est circuit which imposes an artificial ground fault on t he load circuit to assure that the ground f ault is st ill f unct ioning. Test and reset but t ons areprovided f or t est ing." Aside f rom being complex devices requiring frequent t est ing, no one can be assuredthat GFCI's will be installed in t he field. The Nat ional Elect rical Code only requires GFCI' s in bathrooms, kit chens and on roof t ops in commercial and indust rial buildings. See Art icle (B) of the 2002 m e d e signers and owners consider t he heat er operat ion essent ial t o prevent f reezedamage t o t heir wat er supply, t heref ore, t hey prohibit t he inst allat ion of GFCI's in t he heat er circuit due t o nuisance t ripping. For t he same reason, GFCI' s are not used onrefrigerat ors and f ASSE, The Nat ional Elect rical Code, UL and ETL:Si n ce it s incept ion in 190 6, t he ASSE ( American Societ y of San it ar y Engineering) hasadopt ed the f undament al policy of " Prevent ion Rat her Than Cure".

8 This policy hasbeen used in t he f ormulat ion of programs t o educat e t he plumbing indust ry and t hepublic in the saf e and correct manuf act ure and inst allat ion of plumbing component ore, backf low prevent ion devices represent a large part of t he ASSE St andardsPr o g r am . ASSE 1 060, The Standard for OUTDOOR ENCLOSURES for BACKFLOW Prevent ionAssemblies was issued in 19 3 The Nat ional Elect rical Code was est ablished in 1 896 and has evolved int o being t hemost widely recognized code in t he world. It is adopt ed by law t hroughout t he Unit edSt at e s. The Code is sponsored by t he NFPA (Nat ional Fire Prot ect ion Associat ion) and is also known as NFPA 7 0 . The Code brings t he lat est elect rical saf et yrequirement s to the elect rical indust ( Un d er w i t er s L ab orat ories) and ETL ( Edison Test ing Laborat ories) are independent , product saf et y t est ing and cert ificat ion organizat ions.

9 UL was f ounded in 1894 andET L w a s f o unded in 1904. These organizat ions t est product s of all descript ions (plumbing, elect rical, mechanical, et c.) t o known st andards and list t hem as cert if ied to the applicable test standard. Bot h are members of NRTL (Nationally Recognized Test ing Laborat ories) by OSHA. page 4