Panel grounding multiple dwelings

[OLDTIMER]

My house is one of four row houses that are conected with one single metal water pipe to the city service[ very outdated arangement and not curent with city standards] this pipe emerges in my basement and branches off to the other 3 houses.My panel is grounded to this pipe and so are the other houses .
Is this safe and code [Ontario]?
Rule 10-700 refers to grounding for [B]single family house not multiple houses.
Help appreciated
Oltimer

[Eddy Current]

How are the services done? Meters inside or out? One service with all the meters or each unit have it's own overhead or underground feed?

[OLDTIMER]

Tnx for reply

Each unit has it own overhead feed, all meters are inside and 99.9% sure none has any grounding rods.Three of these units were rewired about 30 yrs ago ,dont know who did the electrical work or if permits were issued. Where can I call to find out if there are records of permits issued for the electrical work?

[Eddy Current]

The grounding is fine and to code. If I had to inspect that house right now I would look for the ground wire to be connected to the water pipe at the point that it enters that unit. I would also look for a jumper from the cold water to the gas pipe (if there is one)

[b]Rule 10-700 refers to grounding for single family house not multiple houses.


Actually refers to ALL installations. Residential and commercial.

[OLDTIMER]

Thank you for your insight, this common water pipe runs over 30' inside my basement before the ground connection for my house, then splits into a T, over 20' to the right going through a common wall and to the left side is about 30' and grounds 2 houses










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[Eddy Current]

A water pipe is the best option for a grounding electrode. Picture the pipe as a long ground rod that goes under ground quite a distance. Now compare that to a couple of 10 foot rods or a ground plate. The water pipe is the better one. Other houses tied onto that pipe is fine. Remember that there is no voltage or current running on the ground. It is just an easy path to ground in a fault condition.

[joed]

Actually it is a route to ground in a lightning strike and a bond to the water system in case of a short to the water pipes. The fault current flows through the neutral back to the transformer. The neutral and ground are tied together in the main panel.

[Eddy Current]

Interesting.......I had always thought that short current travelled down the grounding electrode like a lightning strike does.

[OLDTIMER]

How is the neutral at the transformer grounded?

[suemarkp]

There is usually a ground rod or a copper sheet on the bottom of the pole holding up the power company wires. The primary and secondary "neutrals" are both grounded to this rod or sheet. So there is always a return path through the earth to the POCO source. A long water pipe and thousands of power poles make a decent path, but it still isn't good enough to trip a 15A breaker at 120V. But it is plenty enough to kill you or allow a decent fraction of the returning current to take this path.

Sometimes, 5 or 6 houses can be fed from the same transformer. Since they all go back to a common neutral, this is very similar to each house being connected to a metal pipe. Even more so since the pipe in each house are required to be bonded to the neutral. So your metal pipes are electrically connected to your neighbors pipes (and my pipes too), even if your water service from the street is plastic.