SES Maxed out

[joser]

I have a 600A SES that has five 200A fuseable pullout disconnects. I am currently maxed out, but need to add one more load center. May total current draw from one load center is 78 amps, while the other is at 58 amps. My question is like this. Can I add two 200A fuseable disconnects outside the SES and wire them from the same 200A fuseable pullout disconnect?. My total current draw on the SES is 320A.

[Wgoodrich]

Before you add load to a main service you need to know that the demand load is already on that service. Once you have figured a demand load calculation then you can make in informed decision whether you can add sub panels to these 200 amp main service rated panels.

Good Luck

Wg

[suemarkp]

If your calculated load is really 320A, then yes you can do this. Your problems are going to be more of a mechaincal one -- how to run two 200A wires from a disconnect lug designed for one. Can you get double lugs? Do you have room to split bolt on a second wire? Do you want to use the tap rules and run these into smaller panels with local overcurrent protection (e.g. 100A or 125A main breaker panels). Why not just put a small 200A panel off one of the disconnects and use 100A and 125A feeders for your new loadcenters?

A 600A service with five 200A breakers is ripe for overloading. Why are there so many 200A pullouts for such a small calculated load? Can any of those other feeders be utilized to serve what you need?

[joser]

First, Thanks for helping out. What's going on with this SES is the following. Before I got involved, the SES had been tapped several times with diffrent load centers without any protection (main breakers) from the same 200A fuseable pullout disconnects. All five. There is a total of five seprate offices and one saw (this is a truss fabricating plant). Slowly I was able to designate circuits to individual load centers, but as you can see, I am one shy. So what I currently have is one 200A fuseable pullout disconnect with to 2 main lugs load centers feeding off of it. With all five offices and saw powered on, my total load is 320A. The SES is 600A. I took some amp readings on all 5 discs. and are as follows:1-28A, 2-78A, 3-40A, 4-72A, 5-69A, SAW-33A, Total-320A. So what I am trying to do is as follows: Install two 200A fuseable disconnects outside the SES, and feed power from a 200A distribution block feed from the available disconnect. What do you think? Will it work? Thanks.

[Wgoodrich]

What it looks like to me is you may be able to solve your problem by taking the smallest load main service disconnect out and replace with a feed through distribution panel.

I question your demand load declaration. Did you take only one amp reading at one given time. How much equipment was not being run in those offices or in that production plant during this amp reading test ? You need to be prepared for all this equipment to decide to run at one given time. Increase your largest motor load 125% then add the full load amp of each piece of equipment that is direct connected or permanently set then calculate 3 volt amps per square feet plus add a total answer of 180 va per receptacle in those offices to that load. Then you need to consider if this is single phase or three phase service. This will give you what your demand load calculation is in approximation per NEC rules. You taking a half dozen readings throughout the day only gives you a rough guess what the demand load is depending on how many people were working, how much equipment was not running at the time of the tests and any future growth involved.

Just my opinion

Wg

[joser]

I will do a complete full test tomorrow on load demand, and we will see where we stand. I understand what you are saying, and I agree. I was not taking certain things in consideration. Once again, thanks for your help and I will post my readings tomorrow. Have a good one.