How to calculate what size of panel is needed

[PG Eng 0]

How do you go about knowing what size of panel to order for a build? Use CAD to scale the components together, allowing a % extra space? Order all the components 1st and mock lay them out? (Which would mean you would have to guesstimate when you are quoting for the job, as you don't know what size and hence what price of panel required..)

[BobLfoot 302]

When I was working for a System Integrator they always CADed the panel using scale component models and don't forget you have minimum clearance distance rules and bend radius for larger wires to account for also.

[PG Eng 0]

Thanks, can you recall what software they used?

[BobLfoot 302]

Gonna date myself here but it was AutoCad R13.

[ElecPneuGuy 1]

I hate to say it.... But if you have to ask that question, you probably shouldn't be doing panel designs....

[PG Eng 0]

We all have to start somewhere... and I don't design panels, but if I ever do in future I'll now know how to size them. Yes, we learn by our mistakes, but we also learn from those with experience.

[TConnolly 13]

I use cad. I create the component footprint in CAD (often I can use a mauf. provided cad file) and put a dotted line box around it to represent clearances. The dotted line box is on a layer named clearances so that I can turn it off later. The component and the clearance box are grouped in a block so that it can be moved together. From experience, I draw duct 1/4" (600mm) wider than it really is. In no cases are parallel ducts closer than 6" (15mm) when components, including teminals, will be between them. Its been years since I mocked up a panel but back in the 80's thats how I did it. To get the initial size for odering a panel before I had all the components I layed out sticks of wire duct on the floor with a yardstick. Real engineers used one of these: but I was pencil challenged before the pc made it pc to be pc (pun intended) Edited 26 Mar 2008 by Alaric

[ssommers 20]

Alaric - I like the idea of putting a clearance box on a separate layer! I've seen too many cases of a Micrologix shoved into a spot where it's impossible to attach the programming cable due to whatever was shoe-horned next to it. I'm like everyone else here... I try to lay it out in CAD first since most of my vendors have at least 2D drawings of the parts I buy. If I'm doing a small build & happen to have all the components on the shelf, I might simply play with them on a piece of plywood. Then I try to allow for 20% spare space, but may fill some of that up with empty terminal blocks so I don't get accused of being wasteful. Remember, stuff expands to fill the available space, so go at least 1 or 2 sizes larger than you think you need if you have the room.

[Clay B. 1]

Clearances are very important when dealing with Drives. have seen pannels where there was not enough room around the drives for them to stay cool and not heat up other parts. I have used smart draw to lay out cabinets. It is almost as good as CAD just cheaper. Always error on the larger side. Open space does not cause problems, not enough space does.

[Taotaoba 0]

At least 20%.

[Chris Elston 79]

There are no "stupid" questions at MrPLC. Please always try to encourage each other. Not directing this to the original poster, but we get alot of college kids that ask questions. I am glad we all help them, they will be our replacements one day, so we have to train them good. Thanks everyone. -Chris

[robh 12]

As large as possible. Theres no such thing as too big. Unless it won't physicaly fit in the building, then you need a bigger building.

[TimWilborne 108]

Rob, I want to come do work for you. I have never done a job where the customer says "Oh, we have plenty of room, make the panel as large as you want" It is usually quite the opposite