How many subs off of a main panelboard

[dionlynch]

I am currently doing a renovation in an industrial building. Basically I am doubling the load of what is exsisting now. As far as I can tell right now I have a 100 amp breaker feeding two subpanels. The most amperage being pulled is on 34.3 amps in one panel and 23.8 amps in another panel. I also think the main is double lugged and the two panels are in parallel. If I'm going to be effectively doubling my load can I just take the highest amp reading and mulitply it by two to get a somewhat accurate account of what I am going to be pulling when the job is complete. All of the added load is going to be computer loads which aren't that much. I also know that you treat parelled and series loads differently. What is my best course of action?

And another thing is, (can't seem to find a diffinative answer in the NEC) how many subpanels can one have off of a main panelboard? Does anyone know the article #.

 

[bphgravity]

1. All loads should be calculated using Article 220 of the NEC.

2. There is no limit to the number of panelboards that can supplyied by one service. Only the number of loads is limited by the rating of the service.

 

[charlie b]

You can always figure out the load by adding the VA for each and every item that is connected to the panel, and seeing if you have overloaded it. But that is not often practical, and is not necessary. 220.87 gives you some other options.

There is no rule that restricts the number of subpanels that can be fed from a single panel. But there is a rule that says the panel?s rating must be at least as high as the calculated load. So if you started with your 100 amp panel, and connected 25 subpanels, each with a load of 4 amps, and then tried to add the 26th panel, you would violate 408.30.