Newbie questions on panel building

[halczakp]

Hi Folks

I am about to start building my first panel that is of a fair size. Therefore I would like to ask for advice on certain things before make mistake. I got myself familiar with posts with tricks & tips on panel building, however still would like to get few bits clarified. They're as follows:

1. What distance would you normally leave between top of device/component and wire duct?
2. I do understand that it is recommended to keep the switching/power part in separate enclosure than control part, how critical this is though? If I have small pumps, few boilers and other bits and pieces without VSD etc. to worry about, do I really need that separation or would it be acceptable to throw everything in large non-separated enclosure? I have larger 'control' part that I would need large enclosure for and then I would left with half empty switching part (relays, contactors, MCBs etc) to match the size of control one, hence the desire in one large enclosure with everything in.
3. How do you attach components such as duct to the door? Is it glued?
4. What wire numbering systems do you use? I am aware there is no standard for it and every organisation using own internal methodology, could you suggest something to start with in order to let me develop own methodology based on?
5. How do you estimate cooling requirement for panel (i.e. fan or vent slots).

Your comments are much appreciated, at the moment I am a little bit limited with choice of enclosures I can use so have to work with what I have access to. I have done some cad layouts following best practice but they do not necessary work well for me and need lot of tweaking. Particularly the distances between devices confuse me. I do not want clutter and also would like to ensure good air flow for cooling and no interference.

Thanks

Pat

 

[rootboy]

"What distance would you normally leave between top of device/component and wire duct?"

Enough distance to get fingers around them should be sufficient. There's no need for more room than that, and at least where I'm at, running conduits from the top of the panel is discouraged.


"I do understand that it is recommended to keep the switching/power part in separate enclosure than control part, how critical this is though? If I have small pumps, few boilers and other bits and pieces without VSD etc. to worry about, do I really need that separation or would it be acceptable to throw everything in large non-separated enclosure? I have larger 'control' part that I would need large enclosure for and then I would left with half empty switching part (relays, contactors, MCBs etc) to match the size of control one, hence the desire in one large enclosure with everything in."

Keeping everything that would require suiting up off to one side is a big advantage. I wish we had done this with our panels.


"How do you attach components such as duct to the door? Is it glued?"

Yup. It's either that, or have nuts welded to the door prior to painting it.


"What wire numbering systems do you use? I am aware there is no standard for it and every organisation using own internal methodology, could you suggest something to start with in order to let me develop own methodology based on?"

I've seen a few, and I prefer the sheets to increment by 100's with each line on the sheet incrementing by 1 (i.e the first line would be 100, then 101, 102, etc.). Split the sheet into two halves, and limit the number of lines to around 20 per side. Start the numbering on the second side at 150. The wire number takes the sheet number and concatenates a 0 for the first contact, 1 for the next, etc...


"How do you estimate cooling requirement for panel (i.e. fan or vent slots)."

Is the panel going to be located at the South pole, or in Death Valley?

 

[cjd1965]

Hi
Are you looking to CE mark the panel? Is it going to conform to EMC ? Is the any risks you need to mitigate etc

I dont want to sound harsh but you maybe wiser having it built for you by a professional panel builder.

Best of luck

 

[uptown47]

"How do you attach components such as duct to the door? Is it glued?"

You can always just neatly 'loom' those wire together, hold them together with a few small tie-wraps and then wrap the whole lot in that plastic loom stuff to make it look neat.

"I do understand that it is recommended to keep the switching/power part in separate enclosure than control part, how critical this is though? If I have small pumps, few boilers and other bits and pieces without VSD etc. to worry about, do I really need that separation or would it be acceptable to throw everything in large non-separated enclosure? I have larger 'control' part that I would need large enclosure for and then I would left with half empty switching part (relays, contactors, MCBs etc) to match the size of control one, hence the desire in one large enclosure with everything in."

I've seen lots and lots of panels that just have everything together (although logically positioned).

"What wire numbering systems do you use? I am aware there is no standard for it and every organisation using own internal methodology, could you suggest something to start with in order to let me develop own methodology based on?"

First part of number refers to the page of the electrical drawings, last part refers to where on the page (page is split into 10 sections numbered 0 - 9).
ie. wire no. 209 is page 20 over on the far right. You can always add 209a / 209b etc if needed.

Just a few ideas...

 

[the_msp]

To attach duct to the door, strong double sided foam pads, as used to hold number plates to a car, have worked well for me.

 

[halczakp]

Thank you all for your answers and advice

@uptown47 I have also seen many panels built by reputable companies that had everything in one enclosure. That is the source of the confusion. Good practice is to keep things separated but IMO unless there are VSD or any particular known sources of noise present I doubt it is so important. Obviously ac cables separated from control equipment and potentially noisy equipment further apart in panel to avoid interference. As I mentioned there are no large motors or anything like it in this project. I have though fair bit of MBUS communication (200+ meters across 3 networks and 3 separate masters translating to RS232 and feeding PLC)

@cjd1965 if I give it to professional builder I will never become one, we all had to start somewhere Taking this occasion you have mentioned CE marking could you advice which standard I need to adhere to, to achieve CE marking and what is the process? I would also appreciate more information about EMC, all standard I have been working with so far are very general about this, for instance section 444 of BS 7671 just gives some clue but no concrete information. It does though refer to other standards for data/communication cabling installation. I would appreciate advice where to look at for more details about panels. Although my panels are to serve building management systems rather than industrial processes I would still like to build them to high standard and be able to achieve CE marking.

Fortunately for this project I have managed in the end to squeeze everything to two enclosures I have originally selected, therefore separation is there. However, I am sure that rather sooner or later this dilemma will come back and soon will end up with decision to install all in one enclosure...at least to prove the point.

Thanks again for advice.

 

[JaxGTO]

Do NOT tie wrap wires in the wire tray. You or a tech later will be cursing you. All glue fails after a few months weld studs or just drape the loom. Have enough room between terminals and wire way to easily use two finger to be able to place the field wire. More room you leave the less the electrician will gripe. Keep all field terminals as high as possible. Good field electricians are usually not young and really line not having to get on their knees to land a wire. Our goal for ac is usually 70-75 F inside the panel. So you have to take in account of yearly high/low of where it will be and then assume 80% max watts output of all devices in the panel. That will get you close to what you should size. Make sure to get a unit with an alarm so you can alert if it dies.
Also talk to the end user and see if they have any spec for the plant before you start.

 

[Pete.S.]

CE marking is complicated. You need to take a course (or several) for that. There are many ifs and buts. You need to produce a lot of documentation.

EN 60204-1 is the electrical standard you need to follow if it's machine of some kind.

If you have emergency stops or safety related components you're in for a treat. ISO 13849-1 is the standard you need to follow.

EMC directive in industrial electrical environments and permanent installations are done by using CE components and follow manufacturers guide on installation and good practice. No EMC testing is needed in this case.

 

[Phil Buchanan]

"What distance would you normally leave between top of device/component and wire duct?"

Enough distance to get fingers in and work with the wires and for the wire numbers to be visible without a lot of effort. Also the height from component to wire duct needs to based on your tallest component on that rail. For example a 3 pole class CC fuse holder will have a lower height plane from the center of the DIN rail in which it's mount than a typical DC power supply does. So take your tallest component as your reference point in general and also consider what may be added to that rail in the future and plan and leave enough room as best you can.


"I do understand that it is recommended to keep the switching/power part in separate enclosure than control part, how critical this is though? If I have small pumps, few boilers and other bits and pieces without VSD etc. to worry about, do I really need that separation or would it be acceptable to throw everything in large non-separated enclosure? I have larger 'control' part that I would need large enclosure for and then I would left with half empty switching part (relays, contactors, MCBs etc) to match the size of control one, hence the desire in one large enclosure with everything in."

This comes from two perspectives which are noise mitigation /signal clarity and arc flash. Noise mitigation and signal clarity is keeping high voltage and high frequency (VFD) devices from causing issues with your control wiring.

Some cabinets have a separator wall inside and split all the primary controls like PLC's, Relays and such to give this area a lower or zero arc flash rating.

If everything is under 60 volts (24 VDC controls)then no arc flash protection is needed. many people push 24 VDC controls in environments where 120 volt AC control signals would be the better choice simply because of arc flash but then throw everything in one panel and so even though you have 24 VDC controls in that panel you still need a moon suit because you have 480 volt drives and contactors in there that have a higher arc flash risk


"How do you attach components such as duct to the door? Is it glued?"

It can be taped using the automotive double sided tape used to attach trim to body panels and even with the heat it does tend to hold up for a very long time. The best method is to spot weld stubs to use for mounting and the best way to do this for a smaller shop is to do your panel design in CAD and many panel manufacturers like Hoffman will let you order custom cutouts and studs welded on etc.


"What wire numbering systems do you use? I am aware there is no standard for it and every organisation using own internal methodology, could you suggest something to start with in order to let me develop own methodology based on?"

There are many methods for this but the professional and preferred method is to use line references that line up with the physical page numbers of the drawings. It also depends on how large and how complex the drawings will be as to which method is best but line references are the way to go in almost every situation IMHO.

I don't use the A,B ,C increment method. For example If I had a 200 page drawing set then on page 41 the line references would be 41100, 41101, 41102 down the side and my first wire number of that reference will be 0 so if L1 on the left side is coming from a power supply on another page such as 24107 then I have a circuit breaker as the first device on line reference 41105
then 24107 would be on the left side of the breaker and on the right side would be 411050 then if I have a limit switch next 411050 would be on the left of the limit switch and 411051 would be on the right.

By using this increment method you will run out of paper before any of you line references run out of sequential numbers.

"How do you estimate cooling requirement for panel (i.e. fan or vent slots)."

There are may tools to do this and I recommend using the tools from the panel manufacturer and the manufacturer of the cooling equipment you intend to use. I use Hoffman as I have both from the same company and a lot of this work has already been done for you. You mention vent fans /slots and here we refer to those as dirt pumps because unless you are in a very clean environment that's about all they are good for. Id does not make a lot of sense to use a fan to cool your components to gain more life from them and use something that pumps dirt into them and can make them fail faster than higher heat does in some cases