What size meter breakers required for this multi-dwelling house?

[pkelectrical]

I have to replace 5 gang stack-able meter along with panels.
I will run 250 aluminium kcm feeder wires. Will run in pvc pipe. 220 amp according to Table 310.60(C)(76)
There is 4 apartments and one house panel, total 5 meters. It is an old house. I did load calculations and 80 amps is enough for the whole house. Each panel has 3-4 over-current devices.
My question is if I can put 60 amp main breaker in each meter and install 60 amp panels. My concern comes from the following:

408.30 General. All panelboards shall have a rating not
less than the minimum feeder capacity required for the load
calculated in accordance with Part III, IV, or V of Article
220, as applicable.
So if the minimum feeder capacity for the whole house is around 80 amps, does that mean I have to put 100 amp breakers in each meter?
Is the load calculated for each apartment or for the whole house?
Or am i reading this wrong? :?
How does that work with mullti-dwelling houses?

 

[LEO2854]

I have to replace 5 gang stack-able meter along with panels.
I will run 250 aluminium kcm feeder wires. Will run in pvc pipe. 220 amp according to Table 310.60(C)(76)
There is 4 apartments and one house panel, total 5 meters. It is an old house. I did load calculations and 80 amps is enough for the whole house. Each panel has 3-4 over-current devices.
My question is if I can put 60 amp main breaker in each meter and install 60 amp panels. My concern comes from the following:

408.30 General. All panelboards shall have a rating not
less than the minimum feeder capacity required for the load
calculated in accordance with Part III, IV, or V of Article
220, as applicable.
So if the minimum feeder capacity for the whole house is around 80 amps, does that mean I have to put 100 amp breakers in each meter?
Is the load calculated for each apartment or for the whole house?
Or am i reading this wrong? :?
How does that work with mullti-dwelling houses?

In my opinion each panel should be a 100 amp panel with a 100 amp main breaker.

Welcome to the forum.:thumbsup:

 

[GoldDigger]

I do not think that each panel needs to be rated to handle the load of the full house.
However, you have not said whether there is a single service drop feeding all of the meters and whether there is a single disconnect before the meters.
If not, then the five mains will meet the six disconnect rule, and do not individually need to match the service size.
But each panel and main breaker does need to be service rated and meet the available short circuit from POCO.

Sent from my XT1080 using Tapatalk

 

[pkelectrical]

Thank you. I've been here before just never registered or post anything

There is only 1 drop feeding all the meters, 250 kcm aluminum wire. rated to handle 220 amps in pvc pipe. The feeders need to be 60 feet long thou.
there is no disconnect before the 5 meters.

 

[pkelectrical]

I am not sure If I need a main disconnect before the meters. From what I read I dont. But maybe is better to be safe than sorry

230.90(A)Exception No. 3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors.

 

[novemberaudi]

In my opinion for 5 meters you do not need a disconnect before the meters. Also I have done 3 large houses that have a 400 amp service, and 2, 200 amp panels. One in the basement for the basement and first floor, and one in the second floor laundry room for the second and third floor. So I'm guessing that if the panel can handle the calculated load coming out of the panel you are ok.

 

[fmtjfw]

I have to replace 5 gang stack-able meter along with panels.
I will run 250 aluminium kcm feeder wires. Will run in pvc pipe. 220 amp according to Table 310.60(C)(76)
There is 4 apartments and one house panel, total 5 meters. It is an old house. I did load calculations and 80 amps is enough for the whole house. Each panel has 3-4 over-current devices.
My question is if I can put 60 amp main breaker in each meter and install 60 amp panels. My concern comes from the following:

408.30 General. All panelboards shall have a rating not
less than the minimum feeder capacity required for the load
calculated in accordance with Part III, IV, or V of Article
220, as applicable.
So if the minimum feeder capacity for the whole house is around 80 amps, does that mean I have to put 100 amp breakers in each meter?
Is the load calculated for each apartment or for the whole house?
Or am i reading this wrong? :?
How does that work with mullti-dwelling houses?

310.60?? 2kV to 35kV

How about the 310.15 tables?

 

[pkelectrical]

310.60?? 2kV to 35kV

How about the 310.15 tables?

^ I looked at the wrong tables was late at night hehe :ashamed1:
Then it would make 230 instead of 220, little difference, but good point.
Im actually thinking of using just 4/0. no need for 250 kcm if the overall load of the house is no more than 80 amps. Just the owner wanted a bigger service with bigger wires only reason I am going that high.

 

[pkelectrical]

In my opinion for 5 meters you do not need a disconnect before the meters. Also I have done 3 large houses that have a 400 amp service, and 2, 200 amp panels. One in the basement for the basement and first floor, and one in the second floor laundry room for the second and third floor. So I'm guessing that if the panel can handle the calculated load coming out of the panel you are ok.

Think your situation is a little different since you have feeders already rated for 400 amp so cant go over that no matter what, even if subpanels are installed from the panels, the 200 amp breaker from the panel wont allow more than 200 amp to go into those feeders.

I am putting feeders rated to handle 200 amps. each meter has 60 amp breaker. So If they are combined total amps =300. But because the 230.90 Exception 3, I am allowed to do this as long the total load for the house does not exceed the load the feeders can handle which is 200 amp. or 205 to be precise.

So I am 99% sure I do not need a main breaker. I will check with the township inspector just to be clear.
Thank your for your reply

 

[electrofelon]

I will run 250 aluminium kcm feeder wires. Will run in pvc pipe. 220 amp according to Table 310.60(C)(76)

I would say that you do two calculations, one for the common service entrance conductors feeding the meters and one for the service conductors/feeders to each unit. For the first, you would use 310.15(B)(16) , formally 310.16 is the table you want to use. However in your situation, note that for a service with multiple disconnecting means, you can size the common service entrance conductors to the load.

Now for the conductors on the load side of the meter, are you going right into your disconnects there at the meters or running a set of service conductors to each unit per 230.40 Ex 1? Some will say that the service disconnect for each apartment needs to be 60 amp minimum per 230.79(D), although some believe that you could put a smaller breaker in there as the 60 amp is the required rating of the disconnect, not necessarily the size of the OCPD. Note that when you consider the sizes allowed in 310.15(B)(7), you would need #2 AL for 100 amp and #4 for 60 amp so not huge cost savings there. There is a price break at above 60 amps for breakers, but again this wouldnt be very big for 5 breakers. Probably the increased labor for a larger pipe size (pipe or SE cable?) for the 100 amp would be the bigger consideration of what size to run.

 

[jaylectricity]

You do not need 100 amp panels for each apartment. 60 is fine for your situation, the house panel can be even less.

Also you don't need a main disconnect as long as the panels are all in one location. You need all the panels in one location or else you'd need overcurrent protection for feeders traveling throughout the building.

 

[electrofelon]

You do not need 100 amp panels for each apartment. 60 is fine for your situation, the house panel can be even less.

Code wise I agree. However there may be practically no cost savings in going with 60 instead of 100 depending on a few factors such as wiring method, location of panels in the units, whether the meters have service disconnects built in, and whether he can or chooses to use 230.40 ex 1.

Also you don't need a main disconnect as long as the panels are all in one location. You need all the panels in one location or else you'd need overcurrent protection for feeders traveling throughout the building.

Unless 230.40 ex 1 is used.

 

[jaylectricity]

Code wise I agree. However there may be practically no cost savings in going with 60 instead of 100 depending on a few factors such as wiring method, location of panels in the units, whether the meters have service disconnects built in, and whether he can or chooses to use 230.40 ex 1.



Unless 230.40 ex 1 is used.

Well he is already talking about multi-gang meter sockets, so he won't be using 230.30 ex 1. I think that exception is for something like a strip mall where you might have a different metering situations for different parts of the building, or maybe you added a separate space and don't want to replace the entire service just to add a meter for the new space.

As for the cost, it depends on what you consider "practically no cost savings." If you draw the line at $100, you might be right. But wouldn't you rather have a $100 than not have $100? You can get a 60 amp 2-pole breaker for $10. What does a 100 amp breaker cost?

 

[jaylectricity]

And #6 THHN is about 3/4 of the price of #4 THHN.

 

[electrofelon]

Well he is already talking about multi-gang meter sockets, so he won't be using 230.30 ex 1. I think that exception is for something like a strip mall where you might have a different metering situations for different parts of the building, or maybe you added a separate space and don't want to replace the entire service just to add a meter for the new space.

As for the cost, it depends on what you consider "practically no cost savings." If you draw the line at $100, you might be right. But wouldn't you rather have a $100 than not have $100? You can get a 60 amp 2-pole breaker for $10. What does a 100 amp breaker cost?

Why does a multi gang meter socket preclude/disallow 230.40 ex 1??? I think the use of this exception is common in some areas and obscure in others. It is pretty common around central NY for apartments. It really comes down to that word occupancy, how it is defined, who is defining it, and how much they look into it You could have an inspector say or think "looks like two occupancies to me" or he could say/think "show me a letter from you building department certifying that these are two occupancies".

As for cost, of course that is up to you and the client. I could imagine a few scenarios where it costs more to do 60 amp instead of 100.

 

[pkelectrical]

I have finished the job yesterday and waiting for inspection.
It was old house and the owner did not want me to drill through foundation and through the wood so I had to place the 5 meter gang in the basement by the window since there was old plumbing heating pipe running across everywhere else and that would violate 110.26E(1)(a).
I placed the 5 subpanels in the old location. I had to run 60 feet of service conductors to the meter gang and about 25 feet of feeder conductors to the subpanels. I ran #4 aluminium to the subpanels and put in 60 amp breakers. I saved about $300 by installing 60 amp instead of 100 amp.
I had to run 4/0 aluminium service conductors because of the working space. The basement is 6 feet maybe 3 inches.
As per 110.26A3 The height of working space should be 6 1/2 feet. Exception 1 sates: In existing dwelling units, service equipment or panelboards that do not exceed 200 amperes shall be permitted in spaces where the height of the working space is less than 6 1/2 feet. Not sure if this has anything to do with the size of service conductors but I just did it just to be safe.

I will update this after the inspection.

 

[jaylectricity]

Thanks for the update. It's so frustrating when people ask questions then disappear with no resolution.

I think $300 is a good savings.

I just paid $300 for a round-trip plane ticket from Boston to Albuquerque that gives me an extended weekend in ABQ.

/leaving Tuesday instead of Monday would have cost me an extra $300