Enough power not enough breaker locations

[mmiller]

I have a number of 800A 480v panels in our plant. All of them are full up with breakers in all positions (14) Most of the loads are small 30 amps or so and then a couple of larger loads maybe 125 and 100a.

Can I take a breaker that is allowed for the panel let say a 125 and run a sub panel with that with say qty of 4 - 30A breakers buying me back a net of 3 positions ?

A second question.
We also have a number of 75kva 480 / 240 delta transformers installed. The system was put in 7 years ago to go with all of our machines which at the time were 480v, we have been upgrading and now most of the newer equipment is only available 240v How large of a transformer can I run off the 800 amp panels? or could I have a more qualified person come in and remove one of the large 800a panels and install a "larger" step down transformer with a multiple 240 sub panels to feed the equipment.

I have the company that did the install 7 years ago coming out to take a look, but I wanted to get other opinions besides just his.

Located in Northern California - we do plastic injection molding and have 56 machines

 

[LarryFine]

Can I take a breaker that is allowed for the panel let say a 125 and run a sub panel with that with say qty of 4 - 30A breakers buying me back a net of 3 positions ?

Yes, loads permitting, of course. Use a 3p breaker in place of three existing circuits, and reroute those, along with your new load, to the new panel. You get as many additional spaces as your new sub-panel allows.

If your new load is a decently-large 3ph load, you might want to place the new load in the existing panel, moving six existing 1ph loads (or equivalent) to the sub-panel instead. This lessens the load on the new feeder.

How large of a transformer can I run off the 800 amp panels? or could I have a more qualified person come in and remove one of the large 800a panels and install a "larger" step down transformer with a multiple 240 sub panels to feed the equipment.

That's not such a simple question. In theory, an existing load at half the voltage requires twice the current. It's usually easier and cheaper to get new loads that match the existing supply voltage. Your idea isn't cheap.

Yes, a qualified person needs to do calculations, not to mention the installation. There is major rework to be done. I repeat the suggestion that getting the equipment to match the existing voltage is the better route.

 

[cowboyjwc]

I'm of the school that you shouldn't limit your spaces, you said something about 4 at 30 amps. If you can install a 100 amp sub panel then that's what I would do, then next time you are looking for space you'll have it.

 

[mmiller]

sub panel

sub panel

I would love to buy the correct voltage machines but most of the all electric servo drive machines are all 240v 3 phase. Most of the machines are from Japan and their servo drive systems are all based around 200v. We have some German machines and they run at 480v

If I were to measure all the loads and add them up my target is 80% of the 800 amp Breaker feeding the panel is that correct ? So i shouldn't exceed 640 amps per panel then. I have a lot of identical machines so I can measure just a couple and determine the entire load +/- a little bit.

I'm having our local supply house quote out some sub panels to see what the cost is going to be.

 

[neutral]

Hi
MMilller, Do you not have a Plant Engineering Dept at the plant you are working for? How long have you been with the company? Have you considered contracting out the work to an Engineering Group or to an outside Electrical contractor with an engineering staff?

 

[Jim W in Tampa]

Many places that have an in house electrician on duty 24 / 7 still hire out larger jobs. We had one that even used company i was with to relamp and repair parking lot lights. If your qualified to do load calculations then sure you can add a sub panel. Lot depends on what all they hired you to do. Maintenance would not usually be adding new but no reason they can't and it adds to your value as an employee if you can save them money.
This comes down to what your qualified to do. Seen one company that let a not too smart
in house man rewire a 240 volt receptacle to a 120 for a UPS for the IT equipment. BOOOM there went $3,000. I fixed the receptacle for about $300. Put them in bind till they got new UPS. Know your limitations.

 

[hotwire1955]

I would love to buy the correct voltage machines but most of the all electric servo drive machines are all 240v 3 phase. Most of the machines are from Japan and their servo drive systems are all based around 200v. We have some German machines and they run at 480v

If I were to measure all the loads and add them up my target is 80% of the 800 amp Breaker feeding the panel is that correct ? So i shouldn't exceed 640 amps per panel then. I have a lot of identical machines so I can measure just a couple and determine the entire load +/- a little bit.

I'm having our local supply house quote out some sub panels to see what the cost is going to be.

Why not put a step down transformer prior to the input of the machine.
We install converting machinery and that is always done. Buy American machines Keep Americans working.

 

[mmiller]

Consultant

Consultant

I have the company that installed the system coming out next week to look at what options are available for us. Even though it was installed only 7 years ago, we kind of hit the ground changing and evolving. I'm all for doing things the right way and knowing when to let others help me out. This is one of those times where I need someone to help me out.

I actually have a bunch of things for him to look at with me, and possibly having him fix, or give me the direction on how to fix it.

I'm in charge of the Maint. dept. here and we have no Facilities Eng. dept to speak of.....not bad thing to consider though.....

I'm also open if there is someone on the forum that works in Northern California would possibly want to come and do some work.

 

[augie47]

My input:
There is certainly no problem with your adding sub-panels at your 800 amp panels for the smaller circuits. This is very common to allow for bigger breakers in your 800 amp panel. Just be sure to keep the AIC ratings in mind and make sure your smaller added breakers have the proper AIC ratings either full or series.

As others have indicated, you can install one or more larger transformers at your 480 panel as desired. You are looking at a 2:1 ratio so 400 amps of 480 would give you 800 amps of 240, but since the 480 volt circuits are a smaller wire you might want to look at the location of the 240 loads and have one or two transformers rather than one large one.
It's a situation where, as suggested, you might want some engineering as you need to consider transformer losses vs cost of installation, etc.

 

[Pierre C Belarge]

My input:
There is certainly no problem with your adding sub-panels at your 800 amp panels for the smaller circuits. This is very common to allow for bigger breakers in your 800 amp panel. Just be sure to keep the AIC ratings in mind and make sure your smaller added breakers have the proper AIC ratings either full or series.

As others have indicated, you can install one or more larger transformers at your 480 panel as desired. You are looking at a 2:1 ratio so 400 amps of 480 would give you 800 amps of 240, but since the 480 volt circuits are a smaller wire you might want to look at the location of the 240 loads and have one or two transformers rather than one large one.
It's a situation where, as suggested, you might want some engineering as you need to consider transformer losses vs cost of installation, etc.

Some very good advice here!



Augie, I read your signature "I'm so old when I got out to eat they ask me to pay in advance" - very funny indeed

 

[mmiller]

Not enough Breaker spaces update

Not enough Breaker spaces update

So I talked with the company that did out initial install. They are going to send out a guy with the proper PPE gear and will take amp readings on all of our panels and see where we are at. He will the determine what I can do as far as adding sub panels and make some more room in the main panels.

Also we are going to look at a few transformers that I suspect are on the edge of having too much juice pulled through them.

Thanks for all the input on this.