Do they use DIN rail in the USA - Page 1
Forum section: electronics / general

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 13, 2013, 12:13:29 pm
content: I'm speccing some hardware for an installation in the USA - one part can be either DIN-rail mounted or screwed down.Is DIN rail common enough in the US that we can just tell the installers to fit some for us without them querying what it is...?

author: dr.diesel
author_rank: Super Contributor
timestamp: November 13, 2013, 12:15:01 pm
content: Quote from: mikeselectricstuff on November 13, 2013, 12:13:29 pmI use it by the mile in the power industry, should be no problem.

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: November 13, 2013, 12:18:40 pm
content: I have seen it enough to say that it should be acceptable. I don't think anyone will question it.

author: Monkeh
author_rank: Super Contributor
timestamp: November 13, 2013, 12:35:44 pm
content: I've seen plenty of DIN rail used in the US, it shouldn't be an issue.

author: Kohanbash
author_rank: Regular Contributor
timestamp: November 13, 2013, 01:52:52 pm
content: I also use DIN rail regularly in the US.The thing to be careful is that the width is not always the same between vendors. So if the people in the US will need to buy the DIN connectors, terminal blocks, etc.. you need to be aware of that.

author: free_electron
author_rank: Super Contributor
timestamp: November 13, 2013, 03:49:23 pm
content: Yes, but ONLY for control systems.It is not allowed to be used as powergrid equipment (fusebox/breaker box in a building)So it can be on a machine that is either hardwired or pluggable into the building wiring.It can contain automatic fuses .It just can't be used as the buildings main breaker or fusebox. The US uses a bus bar system with hot rails. The breakers plug into the hot bars.

author: AndersAnd
author_rank: Frequent Contributor
timestamp: November 13, 2013, 05:04:52 pm
content: Quote from: free_electron on November 13, 2013, 03:49:23 pmPictures and description of North American distribution boards (fuseboxes)http://en.wikipedia.org/wiki/Distribution_board

author: SeanB
author_rank: Super Contributor
timestamp: November 13, 2013, 07:15:56 pm
content: Just be sure to specify which DIN rail you want them to use, there are at least 2 different that I have come across, a symmetrical and an asymmetric one.

author: Monkeh
author_rank: Super Contributor
timestamp: November 13, 2013, 07:29:30 pm
content: Quote from: SeanB on November 13, 2013, 07:15:56 pm

author: mamalala
author_rank: Unknown
timestamp: November 13, 2013, 07:52:44 pm
content: Quote from: Monkeh on November 13, 2013, 07:29:30 pmI guess that Mike means the first one, TS-35 Rail, commonly called "Hutschiene" in Germany. It's the most common one here in electric installations. Pretty much every distribution/breaker box uses them, most industrial control stuff is mounted on them, etc.Greetings,Chris

author: mtdoc
author_rank: Super Contributor
timestamp: November 13, 2013, 08:10:54 pm
content: They are very commonly used in renewable energy applications in the US - both Off Grid and Grid Tied - in both AC and DC power input and distribution boxes.Midnite Solar is one of the major distributors:LINK

author: free_electron
author_rank: Super Contributor
timestamp: November 13, 2013, 08:18:09 pm
content: Quote from: AndersAnd on November 13, 2013, 05:04:52 pmcorrect.The metallic rails actually carry the current. Fuses snap on to the rails and get their current from the rails.There are two hot rails and a neutral railThe neutral to one of the hots is 120 volt.Between the two hots you have 240 volt.Fuses are a standard widthif you snap a single width fuse the first one gets HOT1 , the sceond one HOT2 the third one HOT1 , so the phases alternate giving an even load distribution on the HOT lines.to get a 240 circuit you snap in a double wide with mechanical linkage. this gives you the 2 HOT wires.the neutral is a separate bar ( the fuses make no contact to neutral , the only fuse towards the HOT feeders )So for every cable you ha ve the bare wire going to the grond bar, the white wire going to the neutral bar and the black wire going to fuse/breakerin the fuse box there is a big shunt installed between ground bar ( bare copper wires ) and the neutral bar (white wires )Ground fault interrupters in the US work bu using a tuned network that uses the white and bare copper ware as an interconnect to close the loop on the transformer in the tuned network. if either the ground wire or the neutral wire opens the tuned network detunes and the GFI trips.So this is different than in europe.In europe a ground fault interurpter trips if the current can flow through a different pathway ( most likely a human)In the US the ground fault trips the moment a wiring fault occurs. This is safer in europe you first need to estalish a current with potentially dangerous results...in Us it trips because there is a defect in the installation making the installation unsafe.

author: mtdoc
author_rank: Super Contributor
timestamp: November 13, 2013, 08:34:08 pm
content: Quote from: free_electron on November 13, 2013, 08:18:09 pmYes, but the NEC in the US also requires GFCI outlets which will trip if there is any potentially dangerous ground fault initiated by human contact. Not sure why that would be any less safe.

author: mamalala
author_rank: Unknown
timestamp: November 13, 2013, 08:51:10 pm
content: Quote from: free_electron on November 13, 2013, 08:18:09 pmIt depends, i would say. If the fault is directly at the appliance, how is the US system detecting that? From your description i understand that it is able to detect a fault in the main wiring, due to the comparatively long wire runs making the detection simple.Let's take a toaster with metal enclosure, for example. Now the PE comes loose from the metal enclosure in some way, and a live wire touches it instead. How can the US system differentiate between that condition, or "no toaster plugged in"? In the EU system, the RCD will trip as soon as a imbalance between the current flowing through the live wire and the neutral wire is detected, which usually means that the current is now flowing to earth/ground instead, possibly through a human. Basically, it's not a ground fault detection at all, but (as the name implies) a residual-current device. They usually trip at 30 mA, and break all lines except PE. Tolerance is -50%, to assure that it will never be higher. They need to trip in less than half a second at nominal, and less than 150 ms at 5 times the nominal current error.I would be interrested to learn more about the system that you speak of. A quick WP lookup does not mention that method you describe for the GFI.Greetings,Chris

author: c4757p
author_rank: Super Contributor
timestamp: November 13, 2013, 09:09:45 pm
content: Quote from: mamalala on November 13, 2013, 08:51:10 pmOh, it's even better here, our metal toasters aren't earthed. Even with a GFCI it wouldn't detect shit.And yet you rarely hear of people being fatally (or not fatally, for that matter) shocked. It's almost like it'sunnecessaryor something...

author: mamalala
author_rank: Unknown
timestamp: November 13, 2013, 09:17:39 pm
content: Quote from: c4757p on November 13, 2013, 09:09:45 pmYea, it was just an example. Of course a person would have to touch the toaster _and_ something else connected to PE at the same time.When they introduced RCD's here, it was first for "wet rooms" like the bathroom. The reason being that a faulty hairdryer or such would pose a risk. And of course if someone would drop that into the bathtub while in it. Later it became standard for kitchens also, and then for pretty much everything else. But only for new installations, old ones can still be used as-is, as long as no changes are made.Dunno about the US (or other countries in general), but here in Germany, the plumbing is usually connected to PE as well. Together with the usual TN-C system used that can pose a risk if someone touches the faucet and some live wire at the same time.Greetings,ChrisEdit: Unless a device has a certain kind of construction, anything with a metal enclosure must have the enclosure connected to PE. Only if the construction is such that a loose mains wire can never touch the enclosure, you can get away without it. I chose a toaster as example because i know of none that could possibly fall under that exemption, due to the way they are constructed usually.

author: Monkeh
author_rank: Super Contributor
timestamp: November 13, 2013, 09:35:26 pm
content: Quote from: mamalala on November 13, 2013, 09:17:39 pmI hope you mean TN-C-S, or your installations have no concept of PE.

author: mamalala
author_rank: Unknown
timestamp: November 13, 2013, 10:13:11 pm
content: Quote from: Monkeh on November 13, 2013, 09:35:26 pmNope, i do mean TN-C. It is the most common connection (and transmission) type here. Three phases plus PEN. PEN is split up into PE and N at either the entry point into the house, or in the main distribution/breaker box. After that it becomes TN-C-S, of course. Any RCD is installed after that splitting point.However, since PE and N are combined before that, current can flow into what is later only PE. Plumbing is connected to a central PE point. But since that is technically also N (they are one and the same at the entry point, after all), from the viepoint of a fault, the faucet (from my example) acts like the N, thus posing a risk.Greetings,Chris

author: Monkeh
author_rank: Super Contributor
timestamp: November 13, 2013, 10:15:31 pm
content: Quote from: mamalala on November 13, 2013, 10:13:11 pmRight, so the installation is TN-C-S. The distribution is TN-C. So far as you're concerned, it's only ever TN-C-S.QuoteThe same risk is present with a TN-S or TT system if that connection is made.

author: mamalala
author_rank: Unknown
timestamp: November 13, 2013, 10:26:25 pm
content: Quote from: Monkeh on November 13, 2013, 10:15:31 pmNot always, We also have old installations in homes/houses that are TN-C, they use what is called "klassische Nullung" to provide PE and N by putting a bridge between the PE and N contacts of an outlet, for example, while the line going to it has only a phase and PEN. But hose are slowing going away, and unsuitable for RCD's anyways.Quote from: Monkeh on November 13, 2013, 10:15:31 pmTrue. But then again, there are nasty old installations where plumbing and other stuff (masts for the antenna, for example) have a local earthing only, and are not connected to the PE or PEN of the supply line. And most of them (at least those that i have seen and modernized) did not have the supply PE earthed locally eithher. So it would be a rather "high impedance" path between a phase and the faucet from my example. But then again, these things are fading away and are rarely seen nowdays.Greettings,Chris

author: Monkeh
author_rank: Super Contributor
timestamp: November 13, 2013, 10:27:28 pm
content: Well, all bets are off with crusty old installs.

author: mamalala
author_rank: Unknown
timestamp: November 13, 2013, 10:34:48 pm
content: Quote from: Monkeh on November 13, 2013, 10:27:28 pmIndeed. Sometimes i wonder how it comes that people survived that new-fangled electricity stuff back then at all. I have seen hair dryers from, uh, 60 or 70 years or so ago (maybe even later). Full steel enclosure, with a two conducter cable with fabric insulation, and a plug that i would not insert into a socket even if i'm drunk like never before.Who knows, maybe people got much dumber over time, and so we need all the extra protection stuff nowdaysGreetings,ChrisEdit: Sorry for all the derail

author: IvoS
author_rank: Frequent Contributor
timestamp: November 13, 2013, 11:56:27 pm
content: Quote from: c4757p on November 13, 2013, 09:09:45 pmNo need to ground toaster oven. Every kitchen is required to have 2 20A GFCI protected small appliance circuits. GFCI provides enough protection against fatality. Trip current is set to 5-6mA. Some receptacle installations upgrades allow to use GFCI on old BX cables without ground conductor, but must be marked "no equipment ground". There is a differential transformer inside, current imbalance greater than 5-6mA between neutral and phase conductor (leakage to ground..etc) will trip the GFCI and safely disconnect the load.

author: IvoS
author_rank: Frequent Contributor
timestamp: November 14, 2013, 12:00:28 am
content: DIN rail is used on specific equipment like elevator controls, emergency battery backup system etc. not on regular house or commercial wiring and power distribution.

author: IanB
author_rank: Super Contributor
timestamp: November 14, 2013, 12:31:25 am
content: Quote from: IvoS on November 13, 2013, 11:56:27 pmThe reference was to pop-up bread toasters, in case it makes a difference. And those have exposed live heating elements inside the slots that are easy to touch by poking a metal knife inside. And they all have two pin power cords, without exception. The only (small) household appliances in the US with three pin plugs are the ones where a signal ground is needed for noise emissions reduction purposes, like computers.And every kitchen doesnothave a GFCI circuit. New installations may do, but most kitchens out there are not new installations.As others have implied, the risk of electrocution in the home is greatly exaggerated. GFCIs and AFCIs are mandated due to lobbying by those who profit from selling them.

author: c4757p
author_rank: Super Contributor
timestamp: November 14, 2013, 12:40:06 am
content: Quote from: IanB on November 14, 2013, 12:31:25 amSmallhousehold appliances. I'm pretty sure your washing machine and refrigerator have exactly as many ground pins as mine do - one each!

author: IanB
author_rank: Super Contributor
timestamp: November 14, 2013, 12:45:23 am
content: Quote from: c4757p on November 14, 2013, 12:40:06 amYup, I forgot about thosePost edited.

author: free_electron
author_rank: Super Contributor
timestamp: November 14, 2013, 02:42:41 am
content: The european GFI only trips if a person touches a live wire .the us system trips both on a person touching a live wire AND a faulty neutral or ground connection.Essentially the us system has a redundant ground. the neutral and the ground are tied together in your fusebox.if one of the redundant wires disconnects the GFI will trip as an indicator you lost redundancy.

author: Monkeh
author_rank: Super Contributor
timestamp: November 14, 2013, 02:50:00 am
content: Quote from: free_electron on November 14, 2013, 02:42:41 amA 'european GFI' will trip on any adequate current imbalance. A person touching a live conductor is not the only source of such imbalances.

author: IvoS
author_rank: Frequent Contributor
timestamp: November 15, 2013, 08:53:19 pm
content: Quote from: Monkeh on November 14, 2013, 02:50:00 amSame in US.