Most circuit breakers in the US just open the Hot wire. For some newer style ground fault & arc fault breakers, the neutral wire goes through the breaker. but they are usually fewer than the standard hot-only breaker.
In theory, if the neutral and earth are bonded (because they are essentially the same, unless we start talking about generators) then only cutting the Live / Hot wire, would be absolutely fine.
The important detail being to protect the user downstream, by cutting power when a fault is detected.
Earth leakage, over current etc etc
Exactly the same in Denmark…
If someone uses the earth wire as neutral, it will disconnect the installation (all of it) in Denmark, cause we have a “Safety Breaker” relay (In Denmark its called HPFI relay) which will disconnect all power, if there is more than 30mA between the live/neutral and the earth wire. I think these are the english terms of the same relay/same principal:
GFCI - Ground Fault Circuit Interrupter
ELCB - Earth Leakage Circuit Breaker
RCD - Residual Current Device
RCCB - Residual Current Circuit Breaker
And I agree with Stuart, if someone uses the earth wire as neutral after the main breaker, (even though it may work) things can go seriously wrong.
2 Likes
There are a lot of replies, so i won’t quote, but let me clarify one thing. In the US 99% (or maybe 100?) of private houses are built of plywood, so it’s quite logical that they mandate metal pipes.
It depends what you call house … If it’s a single family house (2-levels), then YES the houses are primarily built of wood. If it’s a high rise building as in large metropolitan areas, then NO, there the ‘skeleton/frame’ of the building is metallic.
As for metal pipes, that really depends on the actual State (Province). In some states (e.g. Michigan) no metal pipes are required.
@JB_63 I said PRIVATE house. I meant own house for a family. Of course metropolitan building is a different story
@JB_63 By the way, regarding your initial question, i’ve remembered one thing which potentially could save you from a lot of cost and troubles. Have you actually inspected your switches and wires coming to them? For example here in Russia there’s a common practice to do all the wiring using a single type of 3-wire cable (L, N and PE). It’s just easier for workers to manage one big supply of a single type than several different smaller supplies. So, as a result cables running from junction boxes to switches also have 3 wires, with one being unused. And if you’re lucky you may find your house having the same feature. You can pick up and use this wire, and it will cost you only rewiring junction boxes. Of course this is way less destructive, even if your junction boxes are hidden in walls.
Do you live in family house or apartment, BTW ?
It looks like we’re talking about slightly different aspects:
- My point is that, even if you look only at PRIVATE houses, while maybe 100% are built with wood …
- … not ALL of them have metal tubings (conduits)
- In many states, metal tubing is NOT required/mandated
Thank you. Yes, my plan is as follows:
- Identify which switches I need to replace with smart ones.
- Inspect if possible (neutral available)
- If not, use smart lamps instead of smart switches.
I have not started yet, maybe I’ll have some time over the holidays to do the work.
In Ontario, the largest province in Canada, there is no metal tube containing the wires. They’re just wired through the studs. But I think there is code on how far they have to be from the dry wall. That makes it interesting whenever you need to nail or screw something through the dry wall. You need to use a tool to check if there is live wire behind, except most of the times the tool always beeps even if there is no wire.
1 Like
Yes, I totally relate. Many things hidden behind walls, and you need multiple tools before you drill:
- Stud finder if you want to attach heavy objects
- Thermal camera to make sure you do not drill through HVAC conduits or water pipes
- Large waste tubing (PVC) from toilet and bathrooms
- Other tool to detect electrical wires
- Not sure how to scan for low voltage cables (Cable TV and Phone lines) …
It depends on when the house was built and the nature of the house. Older houses will be built of brick, stone, or other materials.
But the most homes built in the last 50 years will be made with Wooden studs, usually on 16 inch centers with a first layer of plywood on the exterior followed by weather proofing fabric or plastic and then an exterior covering like brick, wooden siding, stucco, etc). The interior of the wall is covered with drywall.
The subfloor is usually made of wooden rafters with a plywood subfloor on the ground side, and drywall on the ceiling side. Rarely do you find plywood on interior walls where the bulk of electrical wires are run. If it’s an older home, instead of drywall you will find wooden slats covered with plaster.
Exterior walls will have insulation between the drywall and exterior plywood. Depending on the age it can be any number of materials from batting, fiberglass rolls, spray foam, etc… Interior walls typically remain hollow.
I think it would be more accurate to call this “made of wood” than to specify plywood as plywood really makes up the minority of the materials that go into a house. An I’m using plywood loosely to also include waferboard, chipboard, and any number of other “engineered” sheet good.
Because the electrical wires are typically double insulated (each of the three strands of romex are insulated individually and the whole bundle has it’s own insulation layer) couple with the requirement that all splices and joins are required to be in a box, I’m not sure what the requirement for conduit buys you. The wire is already double protected by insulation and further protected by the fact that it’s inside a wall.
Given my experience, I’d say it’s much less than that. I know it’s not required in Colorado, or Texas where I’ve own homes. I think it’s not required in Virginia, Maryland, Alabama, and Florida. I’d surprised if it’s required in many if any states west of the Mississippi except maybe California where there is the added complexity of earthquakes. Places like Chicago and San Francisco that have had major fires in their history probably have more comprehensive codes for this.
But, I can see where one might want to put all the wires in conduit if you have spray insulation on the exterior walls. It would be pretty challenging to run replacement wires an the like through that insulation.
1 Like
Why is that logical? (did I miss something here?).
We have plenty of houses build using wood. The electrical installation is either PVC pipes (with single wires in it) or cables. Never have I heard an argument for the structure of the house. I suspect it´s the fear of eletric circuts which could turn into fire. Well, perhaps in the very very old days. But my guess is, metal pipes was “invented” because plastic/PVC was either not invented or too expencive to use. Lots of fires has started because of problems elsewhere. Very few in the direct installation.
Also remember that North America uses a much lower voltage than is used in Europe. That alone makes things a little less hazardous.
Ofcouse, if you shortcircut a phonewire having 60amp fuse infront, then things will get hazardous :-
I know the lower voltages makes it a bit different. But the principal is still the same. Metal pibes are no good, infact in my opinion I find them rather dangerous, specially when you try to pull wires around a very short 90 degrees corner or a “T-bend” (dont know the english word for it)… You may risc damaging the isolation of the wires. Thats when things starts to get hazardous. Specially if you, like someone said, have used the earth wire (grounding) as neutral.
1 Like
Metal tubes contain fire much better. For inctance here metal piping is also mandated inside wooden structures. However in practice i agree that if a plain cable with no connections in the middle is on fire, things have already gone so wrong that there’s definitely something else already in ashes.
Ok, guys, anyways, let’s not start standards fight here. It is actually interesting for me to read about standards in different countries.
1 Like
Same in Germany, and on new deployments (or when you’re making “substantial” changes to your housing installation), you even have to spend one of these per room/circuit.
It’s not about starting a fight. It’s more about having a healthy discussion and hopefully learning something from one another. Maybe the confusion stems from this:
- You said: 100% of houses are made of plywood (not really), that is why they MANDATE the use of metal conduits.
- My reply (and others): No, only very FEW states MANDATE the use of tubings. Thus, the reason is NOT because of wood.
I hope this clarifies things. Though some building codes are there for a reason, either historical (big fire of Chicago) or else, and for some, we might never find the true reason. Standards are standards … just live with them and do NOT challenge them, or else you’ll have problems with the insurance company.
1 Like
Thats news to me. I wonder if this is german national law or a EU upcoming law (or rule)?
I’d have to check, but I think that is the ‘preferred’ setup here, under the 18th amendment of the UK wiring regulations.
However it’s nearly impossible to get a straight answer out of anyone, because (and I’m sure this is the same the world over) no-one wants to be accountable, so better to say ‘you could’… Rather than, you should / must.