So I cleand up my power strip design and crated a thingiverse “thing”.
seems to lack even the most basic of over current protection, what happens if someone plugs 12 x 2000 watt heaters into it?
@Steve_M Same thing that will happen if you plug it in directly. It is designed to handle more power than a normal fuse can deliver but yes if you have a 63Amp fuse on 240V you have a problem but then again so would you with 99% of other power strips on the market.
i guess power strips here are different, you can’t plug more than 10A into them without tripping a protection circuit in the power strip to stop it melting the wires in your house
@Steve_M Interesting. Is here by any chance England? That is the only country that has a “weird” power grid that I know of.
USA is the same.
Are you sure its not to protect the power strips itself and not the house. If you do connect a Power strip that is designed for 10A to a 16A fuse then you could melt the power strips but not the house. The wagon module I used can handle 400V and 32A not something that exist in any normal socket.
@Kenneth_Johansson The circuit should be viewed in its entirety, not “house” vs “power strip”. When fire starts it doesn’t care if it starts in the strip or the wall.
In most western countries power strips have button breakers or fuses these days though not all. As long as your wire is sized appropriately and the upstream overcurrent protection is adequate there won’t be an issue.
That’s more the case in the EU or UK where the plug board sizes/ratings are the same as the 13 amp outlet rating/overcurrent protection. In the US it’s a bit different because there could be a 20 amp 120 vac feeding a 15 amp power strip. We would use something like this https://www.tripplite.com/waber-by-tripp-lite-10-outlet-industrial-power-strip-15-ft-cord-large-plug-spacing~UL800CB15/
In the USA, theres a thing called the NEC and UL. Anything electrical needs to comply with that.
TBH, I dont know if something 3d printed can pass UL. You at a minimum need to have an overcurrent protection switch and fuse built in, with wiring and recepticals rated for the intended load +25% above the OCP.
@Patrick_McMicken You misunderstand how the NEC and UL work. The NEC is jurisdictional dependant, it’s not enforced as a federal standard. While most jurisdictions adopt the NEC at least in part (and in some cases exceed the NEC and in others don’t use it at all) it’s still a safety reference manual from a trade association. In this case NFPA.
UL is a testing lab that certifies designs and implementations to proprietary standards. While well regarded, like NFPA, UL is not compulsory by federal law. There are some code requirements that require “listed” parts but UL isn’t the only listing available. There is also CSA and CE.
The process for getting this particular part a “listing”, or certification is no different than the cert the power strip I referenced in the post above. You fill out paperwork, submit the design and products, pay the money and they test them. If it conforms to the spec and passes, you get to put the UL label on it. There is no reason that a properly engineered, appropriate material 3D printed part couldn’t get a UL cert.
@Kenneth_Johansson What’s weird about our grid?
Our outlets each provide for 13A maximum. Our plugs are fused according to the load requirement upto that maximum and distribution bars have a supplementary fuse.
Our main panels feature RCDs which are replacing older fuse boxes as work is done on existing installations.
Our 3-pin mains plug is exemplary in terms of electrical safety and has prevented many an accident in UK homes.
The Institute of Electrical Engineers who set the wiring standards in the UK have done an excellent job. Others could take note.
If you were alluding to our use of 240V, it reduces the wiring gauge on equipment. Much like our 3D printing technology is moving to 24V vs. 12V. See the analogy?
I think EU plugs and cables are just always designed to handle 16A, which is the standard maximum fuse for households. Which means there is no need for extra fuses “in line”.
@Nathan_Walkner Cheap $2 chinese ones maybe but some have a bi-metallic strip that heats up if you try to run more than 10A through it and disconnects the power. It’s not an instant over current like say an RCD style thing out in the fuse box but it still stops you putting more load on the original wall socket the power strip is plugged into than it was designed to handle. I can imagine a power distro board like in the OP in use in a house full of teenagers. Hair dryers, heaters, mobile phones, all plugged in at once drawing 30 amps out of a socket probably designed for half that, in use in an old house with wiring insulated in old deteriorating plastic insulation.
Hell, even a 2000 watt vacuum cleaner + a 1500 watt heater plugged into the same power board is 3500 watts which is over the maximum rating of 2400 watts for power boards here and that’s only 2 devices. I know not everywhere is the same and some have more current capacities but I do worry that people will see something like this, copy it and have no consideration for the single wall plug it’s plugged into.
@dstevens_lv , with all due respect, I dont misunderstand NEC and UL. To use any product in the USA, it basically must comply with the NEC, and be tested (UL or Intertek) to comply with that standard. Every state in the US requires products to comply with one of the versions of the NEC.
So while the codes and regulations may vary, you can substitute “local electrical codes” with the NEC, and “certified” with UL or Intertek.
@Nathan_Walkner , I would hope that theres a 15A fast-blow glass fuse in that strip! If not, you bought too cheap!
@Nathan_Walkner I’m with you on this. I would say that a power strip with a fuse is very uncommon. I have never seen one but then I only have experience with sweden. The law here is that it have to be mark with the max load but no need for a fuse. Then in reallity everything is marked with 16A 250V so it’s impossible to overload.
@Patrick_McMicken Over four decades I’ve worked extensively with issues dealing with the NEC and electrical code compliance and the various listing agencies in both manufacturing and construction. In short, I’m well familiar with the NEC and the requirements for listing.
To SELL an electrical product in the US it is not required to have either NEC compliance or a listing with a compliance/testing lab. You may need an FCC cert for radio emissions but there is nothing in the CFR that requires compliance in a general manner. To state that every state has regs that require it is also not correct.
In many cases though, a listing or compliance to the NEC is required to USE a product in a particular application. That’s where the inspection mechanism comes into play.
@Nathan_Walkner Where you are going to see fuses in power strips is in the UK. They are installed in the plug. As you’ve seen over here you won’t see it.
Over here the better quality strips have good overcurrent protection and even GFCI on some. Those aren’t the sort you’ll find in the local big box store. And they are pretty expensive comparatively, between US$50-100 each in most cases.
On the cheapies you’re just as likely to melt the neutral on the plug before you melt anything in the strip. The internal rails you’ve seen on the cheap strips is a common method of construction though on the more robust strips it’s more substantial and higher quality.
@dstevens_lv UK power strips must have a fuse in the plug however many are also provided with another in the power strip itself. These are held in place by a pull-out carrier.
beware of the FSM! 