Tap Rule Question

[Machiavelli999]

I am wondering if 240.21(B) Feeder Taps applies to my situation.

We are trying to tap the bus of a multi-meter, service switchboard which has a main fuse (1,000A). There are multiple meter sockets but no space for an additional one. We are trying to tap the bus and the tap conductor length and size is an issue. There isn't much space around this switchboard so the enclosed meter-main box would have to be about 10 feet from the switchboard. The tap conductor length would be greater than 10 feet.

Is this whole situation governed by the rules spelled in 240.21(B) feeder taps? Or are these considered service conductors and so governed by 240.21 (D) Service Conductors which just refers you to 230.91 which doesn't really specify any restrictions on lengths.

 

[texie]

If you tap down stream of the main then tap rules would apply.
But a bigger question for me is can you do this at all in a compliant way? In many areas the AHJ would require a field evaluation from a NRTL to do this.

 

[jap]

I think he's asking would that tap be a "Service" tap or a "Feeder" Tap, which is an interesting question when you start to think about it.

Jap>

 

[texie]

I think he's asking would that tap be a "Service" tap or a "Feeder" Tap, which is an interesting question when you start to think about it.

Jap>

If the tap is on the load side of the main then it is a tap and tap rules would apply. If on the line side then they are service conductors and tap rules do not apply.

 

[jap]

If the tap is on the load side of the main then it is a tap and tap rules would apply. If on the line side then they are service conductors and tap rules do not apply.

In a group metering setup the main is simply the overcurrent protection for the service conductors.

Are you saying the buss bars on the load side of that protection to the back of the meters to the line side of the tennant mains are not still service conductors?

JAP>

 

[texie]

In a group metering setup the main is simply the overcurrent protection for the service conductors.

Are you saying the buss bars on the load side of that protection to the back of the meters to the line side of the tennant mains are not still service conductors?

JAP>

Correct.

 

[jap]

Interesting.

What are they then? Feeder Conductors?

Jap>

 

[david luchini]

Interesting.

What are they then? Feeder Conductors?

Jap>

Yes, feeder conductors. The Code is pretty clear that the service conductors end at the service disconnecting means.

 

[jap]

Yes, feeder conductors. The Code is pretty clear that the service conductors end at the service disconnecting means.

And if you're considering the conductors on the load side of that overcurrent protection device to the line side of the meters "Feeder" conductors, why aren't the neutral and the ground points in a Group Metering setup not seperated?

Jap>

 

[augie47]

And if you're considering the conductors on the load side of that overcurrent protection device to the line side of the meters "Feeder" conductors, why aren't the neutral and the ground points in a Group Metering setup not seperated?

Jap>

FWIW 250.142(B) Exception allows that even though they are on the load side of the serve disconnect.

 

[Johnhall30]

Can your situation comply with the 25 ft tap rule? You may have to oversize the conductors

 

[jap]

I guess it all falls back on an install we did a few years back in the (6) movement or less days, where the Power Company would not connect to our 8 socket group metering setup because it had a single main switch type OCPD in the tap box.

It was drawn that way on the plans since there were more than 6 meter/mains and the designer felt it needed a single service disconnect.

In a group metering setup that disconnect generally incorporates overcurrent protection.

The POCO viewed the 8 individual tenant mains as their own individual service disconnects to the tenant spaces (regardless of the number of) and would not allow a switch of any type in their service conductors between the load side of their Xfmr and the line side of the meter bases where they plugged their meters in.

We have group metering of 15 or more meter/mains in our area that do not have a single means of disconnect in the tap box.

The example they gave was as if I were to build 8 individual meter risers next to each other on the back of the lease space, they would swing a service overhead from their pole top XFMR to the risers and connect them all together at the weather heads.

Then said " in that scenario, where do you see a switch of any type in the "Service Conductors" between our transformer and the line side of the 8 individual service disconnects ?",,,,, "You don't".

For that reason, I've always viewed the conductors from their transformer to the line side of a single Service Disconnecting means with overcurrent protection, or, in the case of group metering, the line side of the individual Tenant Mains as the service conductors.

You would think that if the power company actually did view the load side of a single disconnecting means with OCP in a group metering setup as the actual Service Disconnect (where their responsibility of the Service Conductors ends and the customer's responsibility of Feeders begins) , they would make the customer be responsible for the metering such as is the case where EMON metering is installed to meter "Feeder" loads.

Oh well,,,


Jap>

 

[david luchini]

I guess it all falls back on an install we did a few years back in the (6) movement or less days, where the Power Company would not connect to our 8 socket group metering setup because it had a single main switch type OCPD in the tap box.

If your power company forces you to build installations that don't comply with the National Electrical Code, that doesn't change the meaning of the Code.

 

[electrofelon]

Ok unless Im missing something we got into the weeds. Sounds to me like a

I am wondering if 240.21(B) Feeder Taps applies to my situation.

We are trying to tap the bus of a multi-meter, service switchboard which has a main fuse (1,000A). There are multiple meter sockets but no space for an additional one. We are trying to tap the bus and the tap conductor length and size is an issue. There isn't much space around this switchboard so the enclosed meter-main box would have to be about 10 feet from the switchboard. The tap conductor length would be greater than 10 feet.

Is this whole situation governed by the rules spelled in 240.21(B) feeder taps? Or are these considered service conductors and so governed by 240.21 (D) Service Conductors which just refers you to 230.91 which doesn't really specify any restrictions on lengths.

Back to the OP, we need to know whether you intend to tap on on the line side of the load side of the service disconnect. Irregardess (not a word) you may want to read this document:

https://code-authorities.ul.com/wp-content/uploads/2014/04/ul_TappingBusbarConsiderations.pdf

How/if you can tap the bus will depend on how picky your AHJ is and if you have any holes labeled "tap".

 

[kwired]

In a group metering setup the main is simply the overcurrent protection for the service conductors.

Are you saying the buss bars on the load side of that protection to the back of the meters to the line side of the tennant mains are not still service conductors?

JAP>

The main is also the service disconnect. Everything downstream is feeders or branch circuits, even the bus bars in the meter center.

If there is more than six meters there has to be a service disconnect ahead of them to comply with six disconnect rule. 2020 the allowance for multiple disconnects in same enclosure went away - doesn't really change anything for meter centers with more than six meters though as they needed a disconnect for all whether in same enclosure or not.

 

[jap]

The main is also the service disconnect. Everything downstream is feeders or branch circuits, even the bus bars in the meter center.

If there is more than six meters there has to be a service disconnect ahead of them to comply with six disconnect rule. 2020 the allowance for multiple disconnects in same enclosure went away - doesn't really change anything for meter centers with more than six meters though as they needed a disconnect for all whether in same enclosure or not.

I guess they were looking at the tenant breaker as the service disconnect for each individual apartment at the time.

There are several group metering setups around with more than 6 meters yet no single main disconnect in the Man Terminal boxes.

Jap>

 

[texie]

I guess they were looking at the tenant breaker as the service disconnect for each individual apartment at the time.

There are several group metering setups around with more than 6 meters yet no single main disconnect in the Man Terminal boxes.

Jap>

Then they are not NEC compliant. These rules have been in place for many decades.

 

[jap]

The main is also the service disconnect. Everything downstream is feeders or branch circuits, even the bus bars in the meter center.

If there is more than six meters there has to be a service disconnect ahead of them to comply with six disconnect rule. 2020 the allowance for multiple disconnects in same enclosure went away - doesn't really change anything for meter centers with more than six meters though as they needed a disconnect for all whether in same enclosure or not.

Does the 10' Tap rule require the tap conductor to land directly on an overcurrent device, or, can it land on a terminal block and then extend the same size tap conductor to the overcurrent device?

Jap>

 

[wwhitney]

Does the 10' Tap rule require the tap conductor to land directly on an overcurrent device, or, can it land on a terminal block and then extend the same size tap conductor to the overcurrent device?

If the terminal block is just functioning as a splice in the tap conductor, i.e. 1 in 1 out, then the tap conductor does land directly on the overcurrent device. You'll just need to include the terminal block and jumpers to the overcurrent device when checking the length of the tap conductor.

Cheers, Wayne

 

[jap]

Just verifying a No Fuse disconnect could serve as the tap splice prior to landing on overcurrent protection without issue per the 10' tap rule.

Thanks,

Jap>