Future Load - one lateral or two

[ptonsparky]

Customer is expanding his operation now and again in the future. Not soon.
Plan at the moment is to set a 400 amp service with transfer switch that will feed what is planned now. The future load will be an additional 400 amp but will not require generator back up, so an additional 400 switch in the same location as the xfer is anticipated. Can I have two paralleled laterals to this, one set for each 400 or must it only be one set.. Four paralleled for both vs two for each service. Conduit and grounded conductor size would change.

Code reference is what I'm looking for.

 

[tom baker]

So you will have 2 400 amp service disconnects, with parallel conductors to each?

 

[ptonsparky]

So you will have 2 400 amp service disconnects, with parallel conductors to each?

That would be correct. I believe I can only have one lateral to the grouped disconnects, not one lateral for each.

 

[tom baker]

I need to review this before I answer.

 

[augie47]

As I read 230.2 you are o.k. but wait for tom's answer as he's a lot brighter bulb on this tree than i am.

 

[electrofelon]

I dont see this as a a two service 230.3 thing, but rather one service utilizing 230.40 exception #2, so you can have 6 sets, nothing says you cant also use the parallel rules within each set. The key is you can have multiple sets of "service entrance conductors" fed from one "......service lateral" so perhaps you need to be a bit more specific and clarify what exactly it is you are calling a "lateral" (I am thinking it is not a service lateral).

 

[ptonsparky]

It is a service lateral. Direct from a POCO padmount. Two sets of 250 al will give me the 400 I need, with 1/0s for grounded conductor. Tying the 4 sets together at both ends would require 4/0s.

 

[electrofelon]

It is a service lateral. Direct from a POCO padmount. Two sets of 250 al will give me the 400 I need, with 1/0s for grounded conductor. Tying the 4 sets together at both ends would require 4/0s.

OK, so the service point is on the line side meter lugs? I was envisioning service point at transformer spades which is more typical around here. I see what Augie was saying now, and I sort of agree. On one hand the NEC should stop at the service point and everything ahead of that should be invisible, but on the the other hand, 230.2 does use the vague, seemingly catch all term "underground sets of conductors...connected together at their supply end" so it is a rather interesting question. If you take the former perspective, all you see is two laterals, not connected at their supply end, and two services.

 

[synchro]

That would be correct. I believe I can only have one lateral to the grouped disconnects, not one lateral for each.

If you have two laterals will you be effectively paralleling their grounded conductors together anyway through a common EGC and/or GEC that's connected between the two service disconnects? If not then you can ignore this post. If so, then the neutral current drawn at either service disconnect will split and flow through both laterals because their grounded conductors are connected together by the EGC and GEC. And the neutral current that's drawn through one service disconnect but flowing through the other lateral will be conducted through the common EGC/GEC.

 

[ptonsparky]

If you have two laterals will you be effectively paralleling their grounded conductors together anyway through a common EGC and/or GEC that's connected between the two service disconnects? If not then you can ignore this post. If so, then the neutral current drawn at either service disconnect will split and flow through both laterals because their grounded conductors are connected together by the EGC and GEC. And the neutral current that's drawn through one service disconnect but flowing through the other lateral will be conducted through the common EGC/GEC.

Yes, they will be physically grouped on the same metallic support structure. Even if it were wood they would be using a common GE. I don‘t believe that is an issue forbidden by the NEC. FWIW, there will be No normal neutral load, in this case.

 

[electrofelon]

If you have two laterals will you be effectively paralleling their grounded conductors together anyway through a common EGC and/or GEC that's connected between the two service disconnects? If not then you can ignore this post. If so, then the neutral current drawn at either service disconnect will split and flow through both laterals because their grounded conductors are connected together by the EGC and GEC. And the neutral current that's drawn through one service disconnect but flowing through the other lateral will be conducted through the common EGC/GEC.

I dont see that as an issue because that is the same thing that happens when utilizing 230.40 exception #2, or having two services fed from the same transformer (or even different transformers if an MGN system).

 

[jap]

My question would be the metering for the additional future service.

Around here 400a services and below are self contained. 600 and above are generally CT'd.

When the future 400a service is installed will they then CT at the Padmount? and, if so, What will become of the 400a Self Contained meter you will be installing now?


JAP>

 

[electrofelon]

My question would be the metering for the additional future service.

Around here 400a services and below are self contained. 600 and above are generally CT'd.

When the future 400a service is installed will they then CT at the Padmount? and, if so, What will become of the 400a Self Contained meter you will be installing now?


JAP>

Good question, although I dont see any issue with 2 meters as long as POCO doesnt care. Around here is $17/month for a meter. I was also thinking might want to get approval from POCO for the two laterals as I could see them not wanting to do that, in which case one could tap off a single lateral to two discos/meters.

 

[jap]

Good question, although I dont see any issue with 2 meters as long as POCO doesnt care. Around here is $17/month for a meter. I was also thinking might want to get approval from POCO for the two laterals as I could see them not wanting to do that, in which case one could tap off a single lateral to two discos/meters.

It is a good question, but, I'm asking the OP.

JAP>

 

[ptonsparky]

It is a good question, but, I'm asking the OP.

JAP>

CT metering at the secondary of the pad mount

 

[jap]

That should make your life much easier for this install.

JAP>

 

[ptonsparky]

That should make your life much easier for this install.

JAP>

It is easy, just the decision on one lateral or two. Sounds like two is okay.

 

[synchro]

If you have two laterals will you be effectively paralleling their grounded conductors together anyway through a common EGC and/or GEC that's connected between the two service disconnects?

I dont see that as an issue because that is the same thing that happens when utilizing 230.40 exception #2, or having two services fed from the same transformer (or even different transformers if an MGN system).

In the 2020 code, 230.40 Exception No. 2 reads:

Where two to six service disconnecting means in separate enclosures are grouped at one location and supply separate loads from one service drop, set of overhead service conductors, set of underground service conductors, or service lateral, one set of service-entrance conductors shall be permitted to supply each or several such service equipment enclosures.

So I think having two separate laterals feed one group of service disconnects does not seem to be consistent with this allowed exception.

 

[electrofelon]

In the 2020 code, 230.40 Exception No. 2 reads:

Where two to six service disconnecting means in separate enclosures are grouped at one location and supply separate loads from one service drop, set of overhead service conductors, set of underground service conductors, or service lateral, one set of service-entrance conductors shall be permitted to supply each or several such service equipment enclosures.

So I think having two separate laterals feed one group of service disconnects does not seem to be consistent with this allowed exception.

But see 230.2

 

[synchro]

230.40 Exception No. 2 reads:

Where two to six service disconnecting means in separate enclosures are grouped at one location and supply separate loads from one service drop, set of overhead service conductors, set of underground service conductors, or service lateral, one set of service-entrance conductors shall be permitted to supply each or several such service equipment enclosures.

So I think having two separate laterals feed one group of service disconnects does not seem to be consistent with this allowed exception.

But see 230.2

I read 230.2 as saying that for the purpose of 230.40 Exception #2, multiple underground laterals supplying one building or structure shall be considered as supplying one service, and therefore allowed. But I don't see it as allowing more than one lateral to feed the same group of disconnects, which would be beyond the one lateral that's allowed by 240.40 Exception. #2

The illustration on pg. 24 of the following slides illustrates compliance to 230.2 and 240.40 Exception. #2.
Each group of service disconnects has one lateral feeding it.

www.iaei-western.org/Files/2011/Programs/Service%20Installations%20-%20NEC%20Article%20230%20-%202011IAEI%20Western%20Section%20Mtg.pdf