Service Disconnect Before the Meter?

Status
Not open for further replies.
P

Part-Time

Member
Location
Houston, Texas
Can i mount a service disconnect on a commercial building with the mast coming in the top with the service conductors and then run to the meter ?
and then from the meter to the service panel.
 
You cannot re-bond the neutral on the load side of the service disconnect. There was a recent thread here about utility required isolation switches on the supply side of the meter
 
Last edited:
Here isolation switches where required by our utility for 480/277 line metered services for a long time, I think the allowances for them made it into the 2005 code cycle I may be wrong about that but it was way after the common use of them had been around for years
 
It's really more of a POCO question. Other than the bonding situation david mentioned above, the NEC has little to say. Around here most POCOs will not allow a customer service disconnect ahead of the meter (they feel it promotes tampering/theft). They will, at their discretion, call for a "meter disconnect" as mentioned above but they normally lock those with their locks and it is not serviceable or operable by the customer.
 
david said:
You cannot re-bond the neutral on the load side of the service disconnect.
Click to expand...

In this case it may be acceptable. See exception 2.

250.142 Use of Grounded Circuit Conductor for
Grounding Equipment.

(B) Load-Side Equipment. Except as permitted in
250.30(A)(1) and 250.32(B) Exception, a grounded circuit
conductor shall not be used for grounding non?
current-carrying metal parts of equipment on the load
side of the service disconnecting means or on the load
side of a separately derived system disconnecting means
or the overcurrent devices for a separately derived system
not having a main disconnecting means.

Exception No. 1: The frames of ranges, wall-mounted ovens,
counter-mounted cooking units, and clothes dryers under
the conditions permitted for existing installations by
250.140 shall be permitted to be connected to the grounded
circuit conductor.

Exception No. 2: It shall be permissible to ground meter
enclosures by connection to the grounded circuit conductor
on the load side of the service disconnect where all of the
following conditions apply:

(1) No service ground-fault protection is installed.

(2) All meter enclosures are located immediately adjacent
to the service disconnecting means.

(3) The size of the grounded circuit conductor is not
smaller than the size specified in Table 250.122 for
equipment grounding conductors.

Exception No. 3: Direct-current systems shall be permitted
to be grounded on the load side of the disconnecting means
or overcurrent device in accordance with 250.164.
Exception No. 4: Electrode-type boilers operating at over
600 volts shall be grounded as required in 490.72(E)(1)
and 490.74.
Click to expand...
 
Part-Time said:
Can i mount a service disconnect on a commercial building with the mast coming in the top with the service conductors and then run to the meter ?
and then from the meter to the service panel.
Click to expand...

In my area this would be entirely up to the power company. The NEC is OK with wither way.

I would not proceed without contacting the power company for that location and asking them. Or often you can find the info on their web site.
 
Part-Time said:
Can i mount a service disconnect on a commercial building with the mast coming in the top with the service conductors and then run to the meter ?
and then from the meter to the service panel.
Click to expand...

The NEC recognizes this as a "meter disconnect switch" and can not be used as the service disconnect and would have no overcurrent protection. You can only have a meter disconnect switch if the POCO requires same. In others words you would have the meter disconnect, then the meter and then the service disconnect. The meter disconnect can be grounded, like any other metallic items up to and on the line side of the service disconnect, by simply bonding it to the neutral in a compliant manner. Most POCOs I'm familiar with call this "cold sequence" metering. The 2014 NEC 230.82(3) was changed to require labeling of the meter disconnect as such as opposed to a service disconnect.
 
Our POCO requires a disconnect ahead of meter for over 300 V ph to ph. It can have fuses or OCP and in that case its the service disconnect as required by the NEC.
 
texie said:
The NEC recognizes this as a "meter disconnect switch" and can not be used as the service disconnect and would have no overcurrent protection.
Click to expand...

That is a design decision not a requirement,

I can, and do install fused discos or work on jobs with main breakers ahead of metering.

The NEC allows a 'meter disconnect' to comply with the power company if the power company requires that they maintain exclusive control of the switch.

When the power company maintains control of the switch it will have to be designed as a meter disconnect.

If the customer retains control of the switch it can be a service disconnecting means.
 
Status
Not open for further replies.
Top