Non-NEC location - Blank page, what would an electrical safety code look like?

[LarryBen]

I've done work under NEC and a little under Canadian code but now come the opportunity to do work on small isolated systems in non-grid locations. These are nations where the rural grid (when available) is often single wire earth return systems. Don't try to cut the down the pole ground wire there to steal a day's income worth of copper!

These are locations where only metric wire sizes are available, but there are reasonable wire size versus ampacity charts online for the various wiring installation methods (based on IEC standards), so those are a given. Wiring standards for installation under IEC look pretty scary to folks used to our NEC rules but don't seem to kill the users. Their residual current circuit breakers are close enough to our GFCI's for use to understand their purpose.

In locations where many people are barefoot and no one has any electrical user experience, is an ungrounded AC system safer than a grounded system? At least to get into trouble you would have to touch both bare conductors.

Where inverter capacity is too limited to reliably trip a circuit breaker (inverter voltages collapses on fault), what AC circuit protection works best (if any), fuses, breakers, RCCB's? Remember these are locations where there are no hardware / building supply stores for replacement parts. Sure DC fuse or breaker protection on inverter input is a given. If the inverter does collapse voltage on a fault what does a standard output breaker really do that a switch doesn't? (Remember to check breaker operational time curves before answering) An RCCB could work to protect against shock on a grounded AC system but not an ungrounded one.

What would you put in a clean slate electrical safety code for small home solar systems (DC only <50 VDC), small home solar systems with small inverters (230 VAC say <1000 VA), and then for islanded mini-grids (230 VAC single phase) in resource challenged areas?

I realize there will be a lot of opinions and that is fine, but what would a SAFE basic practice for design and sustainable installation and operation look like?

I've got a horror show collection of photos of unbelievably scary electrical installations I've seen in these nations in areas where grid power is available, but these are for areas where no one has any experience with the concept of dangers of an electrical system. So, just saying do it the NEC way doesn't quite work as nothing in the local stores is tested by anyone! I've also seen electrical wire where the measured conductor sizes was about 1/3 of the printed label on the insulation, so the market there is very much buyer be aware and knowledgeable.

Thanks for your ideas and comments.

 

[charlie b]

I have no experience with the systems you are describing. But please allow me to take issue with one of your statements:

. . . is an ungrounded AC system safer than a grounded system? At least to get into trouble you would have to touch both bare conductors.

Perhaps that could be true in the type of distribution system you are dealing with, but it is not true as a general statement. I recall from my Navy days that (1) shipboard distribution systems are ungrounded, and (2) you can still get electrocuted by touching only one live wire. It is the capacitive reactance that would do you in.

 

[petersonra]

The smaller the scope the better IMO.

If you are not interconnecting power generators it makes things simpler. So your simple code should only cover islands.

Only grounded systems need apply.

The generation and distribution would come as a pre-engineered package, approved by some NRTL like organization and include the branch breakers that would have GFCI/RCD protection on each branch.

I think for very small (<1 kw) power generation needs it should be required that utilization equipment it be plug and cord connected.

For medium sized installations (maybe 1-5 kw) allow some kind of fixed distribution system but using cord.

Above that size I think the needs get complex enough that you can't come up with anything simple.

 

[JFletcher]

I have no experience with the systems you are describing. But please allow me to take issue with one of your statementserhaps that could be true in the type of distribution system you are dealing with, but it is not true as a general statement. I recall from my Navy days that (1) shipboard distribution systems are ungrounded, and (2) you can still get electrocuted by touching only one live wire. It is the capacitive reactance that would do you in.

Absolutely true on both accounts.

As far as the original posters questions, I have no experience in that either, however I would think circuit breakers, that are resettable, would be preferable to fuses especially if it would take a month to get a new fuse.

Nobody is going to wait that long for parts, they will put a piece of rebar, long socket, whatever they can cross the lugs to restore power no matter how unsafe or dangerous it is.

Welcome to The Forum. And I would love to see some of the scary electrical work, especially the under-sized, counterfeit wire.

 

[pv_n00b]

I've done a fair amount of work on home and school off-grid systems in Latin America both design and helping install for NGOs. I've also performed engineering designs for commercial export 10MW PV systems that are connected to the national grids. There are electrical codes on the books, mostly based on the NEC. But few people follow them on small stuff and there are no building permits or inspections. On the 10MW systems, the local electrical code is enforced.

I can tell you that for small systems people just put them together with what is easily available locally and cheap. Best thing is to have a really good working knowledge of why things are the way they are in the NEC. While it's usually not possible to follow the requirements of NEC to the letter it is possible to at least follow the spirit of the NEC in trying to protect people and property. You pick your battles. You can tell people not to put acid in batteries while wearing flipflops but you can't make them buy and wear PPE.

As for grounded vs. ungrounded. This is a battle that has raged since the beginning of the electrical age. We are not going to end it here. You use the system that everyone else is using in the country you are in. That way no electrical worker is surprised.

Enjoy the experience.