One building being served by a metallic water line underground and outside has several water lines tapped and coming underground into each tenant space. With a main service disconnect outside and individual service disconnects for each tenant space, can the water line bond be taken from each panelboard?
Water line bonding
- Thread starter TODD B.
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I should add that the individual waterline taps are metallic as well coming into each tenant space. According to Article 250, it sounds as if 250,122 can be used to size the water line bond since the main water line is outside and underground but common to the building.
If by water line bond, you mean just bonding, yes.
If you mean grounding electrode conductor(s), no.
However, if it is all continuous metal water line, your grounding electrode system has already bonded the entire water piping system [250.104]
So you feel that Table 250.122 can be used instead of 250.66
Same answer.
Acording to your statement SMART are you stating that a single grounding electrode from the main service disconnect (which are 750 Al. to 800 a main) one could run a 1/0 copper to one of the metallic water lines coming up through the floor or use Table 250.122 and run a #4 copper from each individual service disconnect panel board to each copper water line entry (200 amp panel boards in each tenant space)
No. I,m saying your water line gec (sized per T250.66) covers the bonding of your water piping system as long as it is continuous metal (you may also need to install bonding jumpers around meters, depends on where they are located). If at any point in the water piping system, sections are electrically isolated through the use of non-metallic piping or dielectric unions or such, then you have to bond those isolated sections. Bonding of the isolated sections can be from the dwelling unit panelboard and sized per T250.122. However, it may be easier and less costly to simply install bonding jumpers between isolated sections.
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