Two services sharing the same ground rods .

[Alaskatron]

Hi , posting a question here from the anchorage , alaska area .

I recently had a storage lot project , where we had two separate 120/240 volt service drops
fed from the same utility transformer that then feed two separate meterbases mounted right
Next to each other on a pipe rack . These were for general site lighting and gate openers .
I was told to drive one set of two ground rods and run the gec. Connecting the two ground rods
And then up into one of the services where it terminated to the neutral/ground bonding lug as normal , and then connecting the gec . from this lug over to the 2nd.meterbases neutral/ground bonding lug . Therefore using one set of ground rods for two meterbases .

My question is , does this not create a solid grounding loop from transformer through first feed and then connected through gec.back on 2nd feed to transformer ?
Should two separate sets of ground rods be used in this case ?
Thanks in advance for any replies .

 

[iwire]

Therefore using one set of ground rods for two meterbases .

Pretty much required. see the part I made red.

250.58 Common Grounding Electrode. Where an ac system
is connected to a grounding electrode in or at a building
or structure, the same electrode shall be used to ground
conductor enclosures and equipment in or on that building or
structure. Where separate services, feeders, or branch circuits
supply a building and are required to be connected to a
grounding electrode(s), the same grounding electrode(s) shall
be used.

Two or more grounding electrodes that are bonded together
shall be considered as a single grounding electrode
system in this sense.

 

[hurk27]

Here we would not get two drops to multiple meter bases on one building unless they were for service of a different type like a single phase and a three phase or of a different voltage such as 120/208 and a 277/480.

A new service would have a multiple meter pack or would have two single meters tied together under a trough with a single riser.

The only time we put in separate risers and meters is when we have two separate properties, such as a condo or zero spacing housing very rare, but in all these cases each unit would be treated as a separate structure and each would have it own meter and riser or lateral, townhouses are common for this type of service and even though they are connected together structurally they are treated as separate structures if under separate owners, here we are not allowed to trespass on another's property, so all utility's including gas, water, cable, telephone, and electric can not be placed upon another's property so each would get its own grounding electrode system.

Condos depend upon how the deed was drawn up, many have a clause written in it to state that the owner only owns as deep as the paint of the inside walls, everything outside including the roof, and outside walls are under a common area clause that might say is under the management of the POA, but if there is no such clause then care must be taken as to where you place the service and run the conductors not installing anything that belongs to one unit on or in the other units.

We had a case at some 6 unit town houses that were sold as separate houses, the electrical contractor installed a 4 gang meter pack on one end and a two gang meter pack on the other end, they ran the feeders under the slab to the middle units, one of the home owners in a end unit decided to install a sunk in hot tub in what was the dinning room because they didn't use it, well his contractor cut right through two sets of feeders to middle units, he was advised by his lawyer that because of the fact that the electrical contractor caused utility trespass he was not responsible for the repairs to get power to the two units, the owners of the inside units took him to court but lost, they had to bring suit against the builder and the electrician who had to re-feed the middle units from meters that had to be located on each unit, even the water lines had to be redone as well as the gas lines, the electrical contractor had to also pay for a place for these two family's to rent until the work was done, it was a very costly mistake, it was a very bad situation as there were no easements in the back of the units so there was no way to run a lateral to each unit without crossing another's property, so the electric and gas meters as well as water, phone and cable all had to be run from the street easement to the front of each of the inside units, floors had to be cut to re-feed them, these owners also sued for property devaluation because of having to have all these meters on the front of their units, the builder went belly up and the homeowners had to go after his bonds and insurance which hired us to finish the electric side of the job.

Just something to keep in mind if this is separately owned units.

 

[kwired]

Is two service drops allowed? Read through 230.40

230.2 mentions multiple underground service conductors connected together at supply end but not the load end is acceptable but nowhere I am aware of is there similar language about overhead service conductors.