Number of spare breakers in a panel board

[Hameedulla-Ekhlas]

Greeting all,
I have one question regarding to spare breaker and space in a panel board.


I have a 3ph panel board as below

total demand load = 150kVA
20% future load = 30 kVA

Total Load demand load + future load = 180 kVA

Now I am thinking about the number of spare breaker to be installed in panel board.

According to me, The spare breaker's load capacity should not exceed the 20% future load. Because in future any time when someone connects a load or a feeder to this breaker that load should not exceed the capacity of spare. If it exceeds than there will be pressure on main breaker.

So, the number of spare breaker in a panel board should be per future load.

Am I right or not please advise me

Is there any special calculation or Code Reference about the spare breaker in a panel board and about the space in a panel board.

 

[ohmhead]

Greeting all,
I have one question regarding to spare breaker and space in a panel board.


I have a 3ph panel board as below

total demand load = 150kVA
20% future load = 30 kVA

Total Load demand load + future load = 180 kVA

Now I am thinking about the number of spare breaker to be installed in panel board.

According to me, The spare breaker's load capacity should not exceed the 20% future load. Because in future any time when someone connects a load or a feeder to this breaker that load should not exceed the capacity of spare. If it exceeds than there will be pressure on main breaker.

So, the number of spare breaker in a panel board should be per future load.

Am I right or not please advise me

Is there any special calculation or Code Reference about the spare breaker in a panel board and about the space in a panel board.

Well i think the code went the other way in 2008 but we had a 42 circuit limit and now its a free for all in a panel .

They manufacture panels with more spaces and they make piggy back breakers people abuse this .

But most jobs i work on the engineer has spare breakers in each panel and the actual load demand is less then the rating of the panel.


How they do this every panel has a different demand and the not the same when you look at the panel schedule its demand is less and a kinda balance load on ABC but can be less or more on each leg .


Your correct in your planning but i can not say what percent of load to panel is correct .

 

[infinity]

There is no NEC requirement to have spare capacity in a panel. The closest thing you'll get is 90.1(B) which is not enforceable.

 

[ceb58]

There is no NEC requirement to have spare capacity in a panel. The closest thing you'll get is 90.1(B) which is not enforceable.

And as a contractor unless it was specified in the drawings to supply and install spare breakers you would not get them. However, if there were X number of spare breakers specked and there were still available spaces left in the panel there would not be any thing stopping some one from adding more and exceeding the calculated load.