200a service cable/100a panel

[iand74]

I have a customer who wants to replace his 100a service cable with a 200a one but keep his 100a MB panel.

Anyone ever do this?

It would be 200a service cable from drop to meter
200a meter
100a service cable from meter to panel
100a panel

 

[infinity]

That's fine but it might not fit into the 100 amp terminals. Also you may need to increase the size of your GEC's

 

[iand74]

That's fine but it might not fit into the 100 amp terminals. Also you may need to increase the size of your GEC's

My thinking was that I'd use 100a cable from meter to panel

 

[Dennis Alwon]

My thinking was that I'd use 100a cable from meter to panel

What is the purpose of this. It does not increase the service size.

 

[iand74]

What is the purpose of this. It does not increase the service size.

The service cable is frayed so needs to be replaced but panel is fine. Customer is trying to keep cost down for now but allow increase to 200a in future.

 

[kwired]

Nothing wrong at all. If this conductor has any length to it it just reduces voltage drop.

Around here we have one POCO that has standard policy for underground services - especially 200 amp and smaller single phase no matter if residential, commercial are all the same. Owner is responsible to bury raceway (to POCO specifications) and POCO pulls and installs service lateral conductor. They do not install anything but 4/0 aluminum for all services 200 amp and under - even if you only need a 60 amp service. So you better install a 200 amp meter socket as the 4/0 is not going to work in a 125, and you can connect 60 amp conductors to the load side if that is all you need.

 

[infinity]

My thinking was that I'd use 100a cable from meter to panel

That would work if the 200 amp meter enclosure had lugs small enough for the 100 amp coductors. Also the GEC woud need to be sized according to the largest service entrance conductors which in this case would be the 200 amp conductors.

 

[jdixon]

We do that up here all the time. most use other half of service to feed unattached garage or out building. Also leaves room to hook-up exterior hot tub or AC unit without filling house panel

 

[jap]

I'd probably put in a Combo 200 Amp Meter Main with a 4 space distribution section, Stab in a 2p 100 in the branch space for now to refeed the existing, then if an upgrade to a 200 Amp in the Future came along I'd intall a MLO Panel and feed it from the 200 amp lugs, then you'd also have distribution on the outside if you needed it.

But thats just me.

 

[jxofaltrds]

The service cable is frayed so needs to be replaced but panel is fine. Customer is trying to keep cost down for now but allow increase to 200a in future.

That would work if the 200 amp meter enclosure had lugs small enough for the 100 amp coductors. Also the GEC woud need to be sized according to the largest service entrance conductors which in this case would be the 200 amp conductors.

(2) Individual Grounding Electrode Conductors. A
grounding electrode conductor shall be connected between
the grounded conductor in each service equipment disconnecting
means enclosure and the grounding electrode system.
Each grounding electrode conductor shall be sized in
accordance with 250.66 based on the service-entrance conductor(
s) supplying the individual service disconnecting
means.

GEC sized to 100 Amps

 

[infinity]

(2) Individual Grounding Electrode Conductors. A
grounding electrode conductor shall be connected between
the grounded conductor in each service equipment disconnecting
means enclosure and the grounding electrode system.
Each grounding electrode conductor shall be sized in
accordance with 250.66 based on the service-entrance conductor(
s) supplying the individual service disconnecting
means.

GEC sized to 100 Amps

That doesn't apply here because you left out the heading of that section "(D) Service with Multiple Disconnecting Means Enclosures."

Take a look under the heading of Table 250.66. It says "Size of Largest Ungrounded Service-Entrance Conductor or Equivalent Area for Parallel
Conductors (AWG/kcmil)"

This single service has two different sized SEC's you need to size the GEC according to the largest.

 

[augie47]

(2) Individual Grounding Electrode Conductors. A
grounding electrode conductor shall be connected between
the grounded conductor in each service equipment disconnecting
means enclosure and the grounding electrode system.
Each grounding electrode conductor shall be sized in
accordance with 250.66 based on the service-entrance conductor(
s) supplying the individual service disconnecting
means.

GEC sized to 100 Amps

IMO, the size would depend on where the connection was made. If you connected the GEC at the meter, I would say you would size it per the service conductors supplying the meter. If you connected at the service disconnect means, I would say size per the service conductors supplying the disconnect.
Again, my opinion.

 

[Smart $]

IMO, the size would depend on where the connection was made. If you connected the GEC at the meter, I would say you would size it per the service conductors supplying the meter. If you connected at the service disconnect means, I would say size per the service conductors supplying the disconnect.
Again, my opinion.

It's my opinion... you can't have it.

 

[infinity]

IMO, the size would depend on where the connection was made. If you connected the GEC at the meter, I would say you would size it per the service conductors supplying the meter. If you connected at the service disconnect means, I would say size per the service conductors supplying the disconnect.
Again, my opinion.

The SEC's begin at the drop. IMO you need to use the largest size SEC's for sizing the GEC even if they terminate in the 100 amp service panel.

 

[jxofaltrds]

That doesn't apply here because you left out the heading of that section "(D) Service with Multiple Disconnecting Means Enclosures."

Take a look under the heading of Table 250.66. It says "Size of Largest Ungrounded Service-Entrance Conductor or Equivalent Area for Parallel
Conductors (AWG/kcmil)"

Correct wrong section:

250.66 Size of Alternating-Current Grounding Electrode
Conductor. The size of the grounding electrode conductor
at the service, at each building or structure where
supplied by a feeder(s) or branch circuit(s), or at a separately
derived system of a grounded or ungrounded ac system
shall not be less than given in Table 250.66, except as
permitted in 250.66(A) through (C).

This single service has two different sized SEC's you need to size the GEC according to the largest.

IMO, the size would depend on where the connection was made. If you connected the GEC at the meter, I would say you would size it per the service conductors supplying the meter. If you connected at the service disconnect means, I would say size per the service conductors supplying the disconnect.
Again, my opinion.

Agreed.

 

[infinity]

Agreed.

View attachment 7490

As stated previously the SEC's begin at the drop. How is using the smaller SEC's permitted where T250.66 says to use the largest?

 

[jxofaltrds]

As stated previously the SEC's begin at the drop. How is using the smaller SEC's permitted where T250.66 says to use the largest?

So are you saying that we 'tapped' at the meter?

 

[iand74]

That would work if the 200 amp meter enclosure had lugs small enough for the 100 amp coductors.

That's a good point that I hadn't thought of. Does anyone know the wire size range for the lugs in a 200a meter?

 

[jxofaltrds]

That would work if the 200 amp meter enclosure had lugs small enough for the 100 amp coductors.

That's a good point that I hadn't thought of. Does anyone know the wire size range for the lugs in a 200a meter?

http://www.milbankmfg.com/Products/Catalogs/CatalogFiles/PDF/REC.pdf

 

[Smart $]

As stated previously the SEC's begin at the drop. How is using the smaller SEC's permitted where T250.66 says to use the largest?

Your interpretation of "largest" is one of at least two possible interpretations:

1. Largest at any routing point along SEC(s).
2. Largest at the routing point where GEC is connected.

We see using the rules for multiple disconnect enclosures that individual grounding electrode conductors "...shall be sized in accordance with 250.66 based on the service-entrance conductor(s) supplying the individual service disconnecting means." What does that mean? Say we have a 600A service with two sets of 350's to a trough above the service disconnects. Three disconnects rated 100, 200, 300 are supplied by taps (which are still service entrance conductors) of #3, 3/0, 350kcmil, respectively. If we use (1) above, we would have to install based on the 2 sets of 350's, because they do supply all three disconnects... and thus the GEC to each of the three disconnects would be have to be 2/0. However, if we use (2) above, we would install GEC's sized #8, #4, #2, respectively. Which way is correct?


With that in mind, you would be compelled to ask why then is it stipulated to use the largest. And the short answer is (I don't know , or...) just in case someone decides to use different size line conductors to compensate for such things as an unbalanced service.