How many pipes can i place on one side of a control box according to code? - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: December 22, 2020, 06:28:52 pm
content: Long story short i have 400 led light bulbs to wire up and it is needed so that i can easily change the switch combinations or whatever crazy idea that may be thrown at it. My idea is for a single bulb there is a dedicated live wire and around 10 bulbs shares a neutral wire and all these are going to a single 30 inch by 30inch by 10 inch control box where they are going to be neatly organized and connected to din railUK5Nterminal block. For any modifications it can now be simply done in one spot. There is going to be a LOT and i mean a LOT of wires around 450 guage 14 AWG wires (guage 14 are the smallest i can buy in the required amount, and all having the same gauge just feels good). Although this will be dismantled in about 2-3 weeks for all the resalable parts to be resold so we can atleast get some money back . I would like to do this properly an do everything up to code (as long it doesnt hinder the primary objective) .We have neatly layed out the pipes and we had decided that we will have 40 pipes going into to the contol box with each pipe carrying the 10 live wire of each bulb and 1 neutral wire. I was thinking making a hole on top of the box likethis(3d view). Would this wanna be electrician pass code ? What are the things i need to work on if not?

author: coromonadalix
author_rank: Super Contributor
timestamp: December 22, 2020, 11:42:33 pm
content: last time i hooked something like this (less wiring loll) i had to be at 1 inch minimum appart of each wire in any direction and use electrical strain relief / cable holdersfor the earth ground, use a copper backplane or a copper bar, and finally for safety reasons use a fuse block on a din rail or a dual switch breaker on each input wire IE: 1x neutral 1x livei hope you have calculated the awg wire lenghts vs the needed current and the possible loss in the wiring(s)

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 23, 2020, 06:51:23 pm
content: I think your pipes (also known as "conduit") might be overstuffed with 11 pieces of 14 gauge unless the 3/4" on your picture refers to the trade size and not the hole size, which appears to be for 1/2" trade size. Generally this can be no more than 40% of the area though there are specific exceptions.(I wouldn't want to pull 11 pieces of #14 though 1/2" anyway! You might not even be able to get them in there.)

author: drakejest
author_rank: Regular Contributor
timestamp: December 23, 2020, 07:01:07 pm
content: The only thing i have not done is placing a fuse i thought the 5a breakers per 10 bulbs is sufficient .the plan is to use 15w rated bulbs , 15 bulbs x 10 bulbs in 1 group is 150 W which should be around 3/4 of an amp assumingg perfect conversion. There is waaaay much more headroom for a 14 guage neutral, i estimate the longest the wire will be is 30 meters . . . Oooor im missing something....

author: drakejest
author_rank: Regular Contributor
timestamp: December 23, 2020, 07:05:59 pm
content: Quote from: Paul Moir on December 23, 2020, 06:51:23 pmApologies the hole is really 3/4 an inch, im not sure how much the outside diameter is.I based it onthis articlewhere the worst case for a 3/4 inch pvc is 17 number of wires.Though the i do not know the validity of the post

author: Nusa
author_rank: Super Contributor
timestamp: December 23, 2020, 07:10:36 pm
content: I suspect almost all of us do not know the code requirements in the Phillippines, since we live in other jurisdictions. A lot of us don't even know the code requirements in our own jurisdiction, since this is more of an electronics forum than a electricians one.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 23, 2020, 07:16:09 pm
content: Since we don't know which code drakejest is using, I just went with my local one. Seems reasonable?

author: WattsThat
author_rank: Frequent Contributor
timestamp: December 23, 2020, 07:33:57 pm
content: Using permanent installation methods on a temporary installation makes little sense. Most codes provide for portable cordage and non-conduit based methods. Best bet is to find a friendly licensed sparky in your country for consultation.

author: drakejest
author_rank: Regular Contributor
timestamp: December 24, 2020, 03:13:04 pm
content: Quote from: Nusa on December 23, 2020, 07:10:36 pmI understand that we are located in different areas, and yes i was expecting to know how you do it in your own country.I think here we based our code on the american NEC,If it was in your area how would it be properly done/?

author: themadhippy
author_rank: Super Contributor
timestamp: December 24, 2020, 03:22:14 pm
content: How many bends in the conduit and how long is it? In the uk we use cable factors and tables to determine whether thing will fit and comply,https://www.rm-electrical.com/wp-content/uploads/2018/08/Conduit-Trunking-Capacity-Chart-RM-Technical1.pdfNot shown is the "fairy liquid" factor,were adding a bit of lubricant can make pulling in the cables a bit easier

author: Renate
author_rank: Super Contributor
timestamp: December 24, 2020, 07:33:24 pm
content: Like a lot of projects this asks for advice on an aspect after much has already been designed, possibly irrevocably.400 bulbs x 15 Watts = 6000 Watts.That's a lot of light.What is the longest run?Why are you presuming AC consumer light bulbs?Did you already buy them? Do they have cords/plugs on them already?Could you use DC LED assemblies?How much switching do you need to do?The easy way to deal with 400 odd wires in a box is not to bring 400 wires into a box.Can you use junction boxes, possibly with switching?You know that DC switching would be easier than AC.Also, lower DC voltage might get you away from any problems with meeting your country's code.You're still talking about a lot of power.You'd need 4-6 1-1.5 kW DC power supplies.Still, that might be better than 400 built-in DC power supplies.

author: wizard69
author_rank: Super Contributor
timestamp: December 25, 2020, 11:00:29 pm
content: This comes back to the old sayingthere is more than one way to skin a cat.For example in automation we avoid using a bunch of pipes by using square wire ducts. These come in a variety of sizes but a 6" square duct can handle a lot of wires. How much depends upon the fill rate for that duct which would require referencing the NEC.Since I really have no idea what you are building here I can't say for sure if your 40 pipes approach is even feasible. In most areas code requires that they be securely installed, that is fastened down. So you would need clearances for all the mounting hardware which I don't see happening on an installation as shown.Remote I/O can be your friend in cases like these. I have no idea if the project is too far along to consider such tech.You make no mention as to how large this display is going to be. One approach would be to position this control box in the very middle and run conduit our all 4 sides of the box. Yo would still have too many conduits so you would run large conduits to sub panels from which the lights could be feed with smaller conduit or cords. Again you would have to calculate proper conduits sizes for all of those wires. Then don't trust those calculations because the results might be correct technically but realistically you can't pull that many wires through the conduits.By the way you need to keep track of the neutrals by marking them in such a say that only circuits derived from a specific breaker are connected to that neutral. That is to avoid overloading a neutral you need to make sure that it is only servicing the loads controlled by a specific overload device. Back in the day we had a process that used a lot of mercury UV lights and use a approach that marked each neutral servicing a sub circuit with an N10x number.By the way you can use a combination of techniques to solve your issues. You can run square wire duct to sub panels that use conduit t run to other panels or junction boxes that then break out to cords to individual lights. Also what you use also depends upon the environment.Quote from: drakejest on December 24, 2020, 03:13:04 pm

author: drakejest
author_rank: Regular Contributor
timestamp: December 30, 2020, 04:54:24 pm
content: Quote from: Renate on December 24, 2020, 07:33:24 pmNo this project has not yet started and it wont be for a couple of months..Quote from: Renate on December 24, 2020, 07:33:24 pmMy bout with DC is it need a lot of other components, especially power supplies getting in the KW ranges are harder to find, i will have to parallel a lot of smaller rated ones. In order to simplify things and removing as many links in the chain the better. With AC i dont need an additional power supply, most outlets can do 1.5KW ( 7-8 amps) no problem and using dedicated light bulbs of the same brightness are a bit harder to find compared to consumer light bulbs that are basically everywhere.With the approach i proposed i basically need only 3 things for it to work somewhat safely. Breakers, wires, Bulbs.

author: drakejest
author_rank: Regular Contributor
timestamp: December 30, 2020, 05:17:27 pm
content: Quote from: wizard69 on December 25, 2020, 11:00:29 pmI like this idea of using square ducts, and i was easily able to find the fill rate. With the 14 AWG (multiwire) i need to only have 40% fill rate for a given conduit size.Quote from: wizard69 on December 25, 2020, 11:00:29 pmI also got this one covered, with the pipes approach i was planningg on using C- fasteners tthey are in the same isle as the pvc pipes.Quote from: wizard69 on December 25, 2020, 11:00:29 pmThis is true but i turned the idea down because having multiple remote devices adds a chance that a singgle remote device might suddenly act up at the worst possible time. there will be a remote io insie the contol box though that switches a or a cluster of lights on the original plan.Quote from: wizard69 on December 25, 2020, 11:00:29 pmevey wire that goes into the box will be labeled. I plan to buy those fancy heatshrink cartridge on the label maker i already have.Quote from: wizard69 on December 25, 2020, 11:00:29 pmThats absolutely true there are many correct ways to do it, so let me rephrase then: what do you think that i will likely do wrong that will violate CODE ?

author: wizard69
author_rank: Super Contributor
timestamp: December 30, 2020, 05:24:56 pm
content: Quote from: drakejest on December 30, 2020, 04:54:24 pmThat is good news. It gives you time to consider options.QuoteIf you are doing a one off project I wouldn't do DC either. I would seriously consider some sort of remote I/O solution though. I just don't see your overwhelming number of conduits going into one panel to be all that feasible.QuoteThis has me wondering is this an outdoor display or an indoor one?QuoteFor something that will only exists for a few weeks this make sense. It would be a different story if it was a long term display or a product. I still think you need to consider minimizing the number of conduits entering the control cabinet. How you do that really depends upon local factors. Personally if it can be done without creating a visual problem I'd put the control panel in the middle of the display and running large conduits to small sub panels. From those sub panels I'd run cords to groups of light arrays.

author: wizard69
author_rank: Super Contributor
timestamp: December 30, 2020, 06:29:30 pm
content: Quote from: drakejest on December 30, 2020, 05:17:27 pmI can't even guess as to what you would do wrong. There are areas of the code that can really get people if they are not careful. I'm going to highlight a few below.First is Conduit / Wireway fill rates. You need to be concerned about max fill rates but then you have the reality that those computations may result in fill rates you can't meet anyways. One way to maximize the number of wires is to use low current branch circuits with smaller diameter wire, however i would not go below 16 gauge here simply for easy to work with materials in a one off.Second; There are also limits on fill rates in junction boxes and the like. I actually find these computations to be a real pain. Generally you are better off going bigger than required anyways simply to make work it he junction box easier. Remember a one off will have a debug period and access can be everything to getting the job done.Third; it always pays to talk to the local inspector before getting too far into a project. This especially in a short term one off project. Inspectors can get a bit over zealous on things that are out of the norm, so keeping them in the loop can result in them being at ease with your project. So not so much a code violation but a way to avoid surprises.Fourth; don't forget your grounding and bounding! The quickest way to an unsafe installation is the lack of sound bonding and grounding.Fifth; I still don't know if this is an indoor or outdoor installation, but if outdoor make sure everything is rated for outdoor use.Sixth; related to the fifth, but make sure everything has a UL or other approval agency stamp of approval.Speaking about that main panel box you first described, that is going to have to be one big panel box to cleanly handle all of those conduits and wires coming into it. That may or may not be a problem. For example if you have 400 bulbs, individually addressable, you will need 400 hundred termination points in the panel along with the associated neutral connections. That is one big terminal strip and doesn't cover any other I/O needs you may have. Also I'd strongly prefer to see all those wires coming into the panel box at the bottom.The next issue is this: do you really need all of those hard conduits? It might make a lot of sense to consider 10 conductor cables (8bits, neutral and ground) to wire in strings of 8 lamps at a time. If you keep your I/O groups properly fused/protected you can go to 18 or 20 gauge cables as long as they are voltage rated and the current on the neutral is withing acceptable values. You need to verify that no specific NEC rule is being violated here, but at the moment nothing comes to mind.By the way remote I/O may or may not be more reliable than having everything operating out of one box. You will want to get a handle on heat in the main panel box. This might not be a huge issue considering LED bulbs these days are in the 5 to 15 watt range. However if each I/O pin results in 1 watt of power being let free in the panel box you can have a ≈400 watt heater in that box. This can lead to having to have fans in the panel box to keep it from over heating. I kinda doubt that your would be loosing 1 watt per I/O point per I/O these days but heat could be a problem in a tight panel box.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: December 30, 2020, 06:45:45 pm
content: Why don't you use a flat cable, such as 10 cables with 41 cores, or even a ribbon cable, where twice as many cores can be laid on both sides in a reasonable width.

author: drakejest
author_rank: Regular Contributor
timestamp: January 09, 2021, 05:59:41 pm
content: Would it be a violation to make our own rectangular conduit?I have looked around in my area and it no one seems to sell rectangular conduits. I plan on making them out from metal that is usually used for metal roofs and have some machinist in the area bend them for me to form a box.Of course wirefill will be observed.By the way this is planned to be placed indoor

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 09, 2021, 07:02:36 pm
content: Quote from: drakejest on January 09, 2021, 05:59:41 pmFlat cables are easily accessible, inexpensive, well laid and cut into connectors - it is convenient.

author: drakejest
author_rank: Regular Contributor
timestamp: January 10, 2021, 02:39:56 pm
content: Quote from: S. Petrukhin on January 09, 2021, 07:02:36 pmUnfortunately its the exact opposite in my area, not easily accessible and are expensive compared to buying them separatly. They usually come in 3 conductor L,N,Earth. And it would be a waste not to utilize earth as the lights we have here dont have earth

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 10, 2021, 05:57:59 pm
content: Quote from: drakejest on January 10, 2021, 02:39:56 pmIf you have a stock of cables readily available, you can use them as you wish. The color marking does not affect the property of the cable in any way, it only helps other people to understand. Many electricians around the world always hope to see a PE (protective ground) on the yellow-green wire. It is bad form to use them differently, but no one forbids you to use them as signal lines, preferably using a label explaining that it is no longer PE.

author: Monkeh
author_rank: Super Contributor
timestamp: January 10, 2021, 06:17:28 pm
content: Quote from: S. Petrukhin on January 10, 2021, 05:57:59 pmQuote from: BS7671:2018Quote from: AS/NZS 3000:2018Quote from: NFPA 70 ('NEC') 2017I'm absolutely positive these are not the only cases, they just happen to be what I have. Once again, I'm really pleased you don't have standards or don't know what they are, butwe do.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 10, 2021, 06:35:10 pm
content: Quote from: Monkeh on January 10, 2021, 06:17:28 pmYour adherence to standards is very commendable. Hopefully, when you need to drive a nail into the wall, you'll find a suitable standard. Or you will find a standard that requires you to read in full what I wrote earler.

author: Monkeh
author_rank: Super Contributor
timestamp: January 10, 2021, 06:38:47 pm
content: Quote from: S. Petrukhin on January 10, 2021, 06:35:10 pmThe bit where you falsely claim nobody forbids you from doing the stupid and dangerous? I read that.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 10, 2021, 06:51:29 pm
content: Quote from: Monkeh on January 10, 2021, 06:38:47 pmMaybe you don't know - we are talking about a temporary low-voltage amateur installation for personal use, created from improvised materials...

author: Monkeh
author_rank: Super Contributor
timestamp: January 10, 2021, 06:58:14 pm
content: Quote from: S. Petrukhin on January 10, 2021, 06:51:29 pmWe're clearly talking about an installation desired to meet appropriate national codes (whatever they may be) at, yes, low voltage. That is the proper definition of low voltage, also known as mains voltage. The regulations, if you don't know, generally apply toall wiring systems, and are pretty clear cut about what these wires can be used for.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 10, 2021, 08:19:50 pm
content: Quote from: Monkeh on January 10, 2021, 06:58:14 pmYeah... The British will never be able to colonize half the world again - they will not have the standards for this.

author: Renate
author_rank: Super Contributor
timestamp: January 10, 2021, 08:25:52 pm
content: Quote from: S. Petrukhin on January 10, 2021, 06:51:29 pmIt's not clear to me how temporary this is.I believe that this is AC line voltage.I believe that this is something that is for public display.Hey, I play fast and loose with some standards sometimes, but I never set myself up for fail/death by doing confusing things intentionally.I never store rat poison in an old aspirin bottle, although it would be most convienent.I only use green/yellow for ground likewise.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 10, 2021, 08:44:23 pm
content: Quote from: Renate on January 10, 2021, 08:25:52 pmRead what is written in the first post: although this will be dismantled in about 2-3 weeks so that all the resold parts are resold so that we can at least get some money back.And I wrote that this use of the PE explorer is not correct, but if necessary it will work. A person has a lot of 3-wire cabels, he wants to use them to connect 400 LEDs-each separately. Throwing 100 cores into the air for the sake of meeting the standard in some temporary minor installation is not reasonable. In addition, sending a signal wire to the PE is not dangerous, and having a signal level on the PE wire is also not dangerous.Calm down with your standards, the World is wider than standards.

author: Monkeh
author_rank: Super Contributor
timestamp: January 11, 2021, 07:28:53 pm
content: Quote from: S. Petrukhin on January 10, 2021, 08:44:23 pmHow many times does it have to be reiterated that we're not talking about 'signal level' (whatever that is)?