Service enterence definiton

[jaehlee99]

Firstly, when sizing the equipment grounding cable at the service entrance, we usually follow the Table 250-66.
However, I can not quite define the service entrance. I am still wondering which table(Table-66 or Table-122) should be applied the drawing what I am doing.
For example, a transformer is owned by customer, does the service entrance begin from primary side of transformer or the other point?
Someone says that if OCPD is installed the place, we have to apply Table 250-122 .

Thanks in advance

 

[fmtjfw]

I assume you use the Canadian Electric Code.
Or am I confused by your location?

 

[jaehlee99]

Even I am in Canada, I am working for the USA project now.

 

[fmtjfw]

Service point

Service point

The service point is where utility wiring ends and the premises wiring begin. If you have a high voltage service is typically where your OCPD is located or where the metering point is.

In our case we have a bit more than 100 metered services. Only two are high voltage, the rest 120, 120/240, 208Y/120, 240 center grounded delta, and 277Y/480.

In one of our installations, it is the air switch on the pole on someone else's property before the fuses and the metering transformers. In another case it is the metering transformers before the fused disconnect before the 7200V oil switch.

Usually the contract with the power company specifies it unless it is specified by the tariffs. [They surprised us when we were shown in the contract that we owned the air switch.]

We have switching rights on those services, but not on POCO owned fused disconnects before POCO owned transformers. [Not that we haven't opened them in emergencies and argued afterwards.]

From there on it is Art 225/399 until we pass through transformers and into buildings or (onto poles holding lighting fixtures). We probably use NESC for high voltage fusing for underground cables and for transformers.

For Code purposes we treat the laterals or overhead conductors from the transformer secondaries as though they were individual "services" in terms of grounding, OCPDs, etc. We use NEC, not NESC (power company) sizing for laterals, and triplex for overhead conductors. We place the OCPDs inside the buildings. We use T250.66 for GECs. The electricity doesn't know where the service point is.

 

[augie47]

From the '11 Code:
Service Point. The point of connection between the facilities of the serving utility and the premises wiring.
Informational Note: The service point can be described as the point of demarcation between where the serving utility
ends and the premises wiring begins. The serving utility generally specifies the location of the service point based
on their conditions of service.

The particulars may vary. The text in red is usually the key.
Where transformers are concerned your system bonding jumper is still sized by 250.66.
A fairly accurate key is to ask "are these conductors directly protected by and overcurrent device. If so you normally use 250.122, if not 250.66.

 

[Dennis Alwon]

Once you pass the service disconnect then use T 250.122 for the equipment grounding conductor. Before the main disco is T. 250.66 and it is called the grounding electrode conductor.

 

[Smart $]

Firstly, when sizing the equipment grounding cable at the service entrance, we usually follow the Table 250-66.
However, I can not quite define the service entrance. I am still wondering which table(Table-66 or Table-122) should be applied the drawing what I am doing.
For example, a transformer is owned by customer, does the service entrance begin from primary side of transformer or the other point?
Someone says that if OCPD is installed the place, we have to apply Table 250-122 .

Thanks in advance

If the customer-owned transformer is pad mounted, it's quite likely there is no service entrance. Also, there is likely no EGC on the primary side.

Your transformer will likely be connected as an SDS. The grounding conductor between the transformer and secondary disconnect is called the supply-side bonding jumper... 250.30(A)(2)(a) wire type ---> 250.102(C) ---> Table 250.66 in each raceway or cable.

 

[jaehlee99]

Thank for your time and consideration.

Have a nice day