Electrical wiring for Timber Frame House

[Monkeh]

Thankfully, we don't use fuses any more, so 2xIn will trip in just a few minutes, and massively oversized conductors are not actually required or beneficial

who said? rewirable fuses are still fairly widespread , the current regs even  has  a correction factor for them.

And do you go around doing new domestic installs with them?

[james_s]

I was watching a video just yesterday, where old Wylex re-wireable fuses were tested in series with modern MCBs. The old fuses blew first every time! 

That isn't too surprising really. Fuses consist of a small wire element that has very low thermal mass. Circuit breakers are electromechanical devices that rely on moving mechanical parts. Many of them are deliberately designed not to trip quickly though, and with fuses too you can get slow-blow types. Otherwise it would be a nuisance if breakers tripped or fuses popped with every momentary overload. My toaster and toaster oven for example are on the same circuit. Both of them together exceed the 20A rating of the circuit but I can still make a piece of toast while something is cooking in the toaster oven without popping the breaker because it only takes a short while to toast a slice of bread. Motors and other reactive loads also can draw large surges that can blow fuses.

[geggi1]

Romania being a EU country your electrical installation is most likely to be done according to an EN(CENELEC) or IEC standard because Romania is a part of EU.
I live in Norway and some of our electrical regulation is most likely very similar as in Romania you can probably do a lot of the installation in a similar way as here.
For in-wall installation we use a plastic conduit (rigid or flexible) with single-core conductors. The conduits are ended in wall-boxes for installing hardware like switches and sockets or roof-boxes for lightings.
Fuses are not permitted to use any more. Now its circuit-breakers with integrated RCD. By having RCD on each circuit and not one for the whole installation an earth-fault will only disconnect one circuit and not give a full blackout.

Check the link showing the kind of wall boxes we are using.
https://proff.elko.no/bokser/category594.html

[tooki]

Circuit breakers are electromechanical devices that rely on moving mechanical parts. Many of them are deliberately designed not to trip quickly though, and with fuses too you can get slow-blow types. Otherwise it would be a nuisance if breakers tripped or fuses popped with every momentary overload. My toaster and toaster oven for example are on the same circuit. Both of them together exceed the 20A rating of the circuit but I can still make a piece of toast while something is cooking in the toaster oven without popping the breaker because it only takes a short while to toast a slice of bread. Motors and other reactive loads also can draw large surges that can blow fuses.

Circuit breakers contain two triggers: a bimetallic strip that is heated slowly to break sustained small overloads after a while, and an electromagnet to break high currents (like a short circuit) instantly.

[Gyro]

Circuit breakers are electromechanical devices that rely on moving mechanical parts. Many of them are deliberately designed not to trip quickly though, and with fuses too you can get slow-blow types. Otherwise it would be a nuisance if breakers tripped or fuses popped with every momentary overload. My toaster and toaster oven for example are on the same circuit. Both of them together exceed the 20A rating of the circuit but I can still make a piece of toast while something is cooking in the toaster oven without popping the breaker because it only takes a short while to toast a slice of bread. Motors and other reactive loads also can draw large surges that can blow fuses.

Circuit breakers contain two triggers: a bimetallic strip that is heated slowly to break sustained small overloads after a while, and an electromagnet to break high currents (like a short circuit) instantly.

Well, instantly apart from the mechanical inertia! In the Wylex rewireable fuse vs RCD MCB video I referenced, in a direct short situation, the fuse blew and the RCD MCB didn't have time to trip, even on the electromagnet.

[Siwastaja]

This is just guessing, but I have a feeling that modern MCBs achieve slightly lower triggering currents than traditional fuses by just moving the uncertainty envelope down, the edge of the statistical distribution going below nominal current.

Why I say this? Because a few times, I have seen a failed MCBs that is overly sensitive. On my dad's place, they just renovated and installed brand new distribution boxes with MCBs and a brand new B10 MCB blows on a nice 8A resistive load all the time. I have reported it, hopefully they will replace it...

Or maybe this problem blowing below In is just magnified by the fact you have to get an electrician to change the part. With classical fuse, if one unit is overly sensitive, it just blows, you replace it with a different unit in a minute and don't think about it further.

But, MCBs are not precision devices either, not that much better than classical fuses in this regard. Maybe you could now design wiring for 1.7*In if you previously had to design for 2.0*In.

You would need more expensive and specialized active circuitry for more accuracy. This is not worth the cost.

[wizard69]

One thing to watch out for is how fuses and breakers are rated.   The EU and the USA have different standards and this has an impact with respect to international discussions.   This is why questions like this are best handled buy people with local knowledge of regulations. 

In the USA I was always taught to avoid loading a circuit past the 80% point if you want reliability, that is no nuisance tripping.   That is due to breakers being designed to trip at their rated current eventually. 

This is just guessing, but I have a feeling that modern MCBs achieve slightly lower triggering currents than traditional fuses by just moving the uncertainty envelope down, the edge of the statistical distribution going below nominal current.

Why I say this? Because a few times, I have seen a failed MCBs that is overly sensitive. On my dad's place, they just renovated and installed brand new distribution boxes with MCBs and a brand new B10 MCB blows on a nice 8A resistive load all the time. I have reported it, hopefully they will replace it...

Or maybe this problem blowing below In is just magnified by the fact you have to get an electrician to change the part. With classical fuse, if one unit is overly sensitive, it just blows, you replace it with a different unit in a minute and don't think about it further.

But, MCBs are not precision devices either, not that much better than classical fuses in this regard. Maybe you could now design wiring for 1.7*In if you previously had to design for 2.0*In.

You would need more expensive and specialized active circuitry for more accuracy. This is not worth the cost.

[Stray Electron]

Probably 95% of homes in the U.S. are wooden frame interiors and as such would be subject to fires in the walls and so forth. We have certain rules about wires run in walls and through wooden rafters and those laws help protect against possible shorts from nails being driven into the walls or metallic objects eventually cutting through the wiring such as clothes hangers hanging on basement wiring. With all of that said the laws requiring outlets and switches to be housed in protective boxes within the walls and correct wire sizing with proper ampacity protection should result in ZERO fires. Sadly when doing things cheaply we had outlets and switches that allowed a 'friction fit' of the wiring and was called 'back stabbing' where the wires were not secured around screws but simply 'pushed in' to the device and with time the wires would have less physical pressure to hold low resistance connections and with heavy loading sure enough you would have a fire in a wall and those are the worst. If all of the National Unified Electrical Code rules are followed there should never be an electrical fire and you could build your house from styrofoam and not worry.

   The stab type connections to electrical outlets and switches have been the source of many house fires in the US but as far as I know, they are still allowed. We just bought a house built about 11 years ago and it has stab connections and several of them show signs of overheating.  My advice is that even if your area allows stab connections, DO NOT use them!  Use the screw terminals instead. It's slightly more work but the connection will stay tight much longer and is much safer. Also make sure that you wrap the wire in the direction that makes the screw tighten instead of loosen.  It's amazing how many people don't understand that simple rule!

[Stray Electron]

In most places DIY wiring by a person who does not carry Electrician’s license is against the Code.

   Where?  In every US state that I've ever lived in, the home is owner is allowed to install their own wiring as long as they follow the local building code. Most laocal building codes in the US follow the NEC (National Electrical Code).  However that applies only to the owner, if you do electrical work for hire then everywhere that I'm aware of requires that you have an electrician's license or work under the supervision of someone that does.

[Stray Electron]

One thing that distinguishes timber frame houses from masonry buildings is that the timber houses get easily on fire and burn down really fast.

  That's not really true.  Most houses/buildings have more than enough flammable material in them that they burn quickly and completely regardless of the building material of the outer shell of the building.  The building is usually going to be a total loss and it really doesn't matter if the outer concrete or concrete-block walls are left standing.

   In the US, in addition to many completely timber framed houses, many newer houses are built from preformed concrete slabs (for the exterior and load bearing walls only) or stacked concrete block. But the roof structures are still wooden framed (and the roof deck is usually wood) and all of the interior walls are also wood framed. Even the inside of the concrete constructed perimeter walls usually have wooden framing.  That's in addition to all of the mostly-likely flammable contents.

   I've seen many totally burnt out houses that had concrete slabs for floors and concrete block walls. in a good number of them, they burnt so fast that the occupants weren't able to escape.

   Speaking as someone who has seen and fought MANY house and building fires! 

   Oh and I'll just throw this in here while I'm at it. I've seen a LOT of house fires and I've seen people die in house fires and it's not something I recommend. As a result, I'm paranoid about house fires so I follow the building codes and best practices scrupulously. For one thing when I added an out building a few years ago i wanted to insulate it and I considered using the spray in foam insulation. But I obtained a sample of it and flame tested it and what I found was that it didn't really burn by itself but if it was exposed to a flame from another source, it burned WELL and made many noxious fumes. As a result I would NEVER allow that to be used in any building that I own. Unfortunately there is a LOT of modern materials that falls into the same category; officially (and by itself) it's non-flammable but when you read the fine print, you'll find out that it does support combustion!  So if you're concerned about the possibility of fire you NEED to do your research and not just rely on what the sales droids tell you. In my case, I found a spray on flame retardant that could be used on wood and I used that on the interior wooden framing and I used the old traditional glass fiber insulation even though that stuff is itchy to deal with.

   IIRC insulating foam like this was blamed as the cause of a large number of deaths in a housing apartment under renovation that caught fire and burned in England a few years ago.

[themadhippy]

Quote

stab connections, DO NOT use them!  Use the screw terminals

youd have thought someone would invent a terminal   with a hole like the stab, but that has a screw to keep things tight ,o hang on

[Jwillis]

Many timber frame (post and beam) homes are wired pretty much the same way a a framed house . This depends on how you intend on doing the wall frames and roof. If your just going with wall studs in between the posts , then the wiring would be the same as a framed house. Only difference is the wall panels are a couple inches narrower than the posts because everyone wants to show off the frame . Roof wiring is done the same way but instead of trusses you would use joists on top of the beams or in between the beams if you prefer that instead about 6 to 8 inches thick then the wiring would go through just like you would walls . This is assuming you want a vaulted ceiling with hanging lights . Since most timber frame homes have an open concept , much of the wire is done in the floor as well.
How thick you make walls and the roof is dependant on the insulating factor you want.
Another way is to use SIPs (Structural Insulated Panels) which have conduits built in. This requires a little more engineering to make sure the conduits match with each panel. Also this method is much more expensive .

[Ed.Kloonk]

   IIRC insulating foam like this was blamed as the cause of a large number of deaths in a housing apartment under renovation that caught fire and burned in England a few years ago.

For so many years here I've watched as peeps upgraded lighting from surface mount incandescent light fittings to flush mount halogen lights. Blokes just cut the 92mm hole in the ceiling, plugbase on the wires, plug in the light fitting. Throw it all in. Never mind the insulation. SMH.

You're supposed to use a white plastic box which houses the fitting and the driver and has a hole which the gimble holds down onto the ceiling. Hardly ever used tho.

Fast-forwarding another generation of lighting, I feel a bit better since the 10w LED has come along, they put off alot less heat and are easier to just swap than bothering with a new halogen lamp.

[james_s]

Quote

stab connections, DO NOT use them!  Use the screw terminals

youd have thought someone would invent a terminal   with a hole like the stab, but that has a screw to keep things tight ,o hang on

We have something vaguely similar to that here, it looks like an ordinary screw terminal at a glance but you don't wrap the wire around the screw, you poke it in a hole and then the screw holds a clamp, they're nice. The contractors still love the cheap spring loaded ones where you just push the wire in and you're done, so they'll pretty much always use those when they're available. The better stuff, spec grade and hospital grade doesn't allow those so that ought to say something.

[james_s]

For so many years here I've watched as peeps upgraded lighting from surface mount incandescent light fittings to flush mount halogen lights. Blokes just cut the 92mm hole in the ceiling, plugbase on the wires, plug in the light fitting. Throw it all in. Never mind the insulation. SMH.

You're supposed to use a white plastic box which houses the fitting and the driver and has a hole which the gimble holds down onto the ceiling. Hardly ever used tho.

Fast-forwarding another generation of lighting, I feel a bit better since the 10w LED has come along, they put off alot less heat and are easier to just swap than bothering with a new halogen lamp.

We have two types of recessed light fixture available here, those that are rated for insulation contact and those that aren't. Fortunately the newer ones all have a thermal protector in them because people often install the wrong type and I've seen the thermal protectors cycling with incandescent lamps.

[james_s]

But, MCBs are not precision devices either, not that much better than classical fuses in this regard. Maybe you could now design wiring for 1.7*In if you previously had to design for 2.0*In.

You would need more expensive and specialized active circuitry for more accuracy. This is not worth the cost.

IMO there is no need for them to be precision devices. They exist to protect the wires, and wires themselves are not precision devices. A wire that is rated to handle 20 amps is not going to burn up if you pull 21 or even 30 amps through it. There is also a good bit of margin to account for things like ambient temperature and whether the wire is buried in insulation or sitting in free air. A breaker just needs to carry something close to the rated load without nuisance tripping and then trip at some point above that but well below the point at which the wire would fail.

Several years ago I replaced a 1950s fuse panel at my friend's house with a modern breaker panel, and when I was sizing up the situation before we began I discovered that the entire basement was on one 15A circuit which someone had at some point installed a 30A fuse! It was wired with 14 AWG wire and the insulation was starting to drip off the wire near where it connected to the fuse block in the panel. That illustrates one of the major problems with fuses, it's very easy for a homeowner to install a dangerously large fuse, either out of ignorance, mistake, or because it's all they have on hand and they'll put the correct one in "later".

I ended up doubling the total number of circuits in that house. There was a freezer in the basement and much of it had been finished into living space with a TV, computers, electronics, etc so that one circuit for the whole space was woefully inadequate.

[drussell]

It was wired with 14 AWG wire and the insulation was starting to drip off the wire near where it connected to the fuse block in the panel. That illustrates one of the major problems with fuses, it's very easy for a homeowner to install a dangerously large fuse, either out of ignorance, mistake, or because it's all they have on hand and they'll put the correct one in "later".

That is why with the screw-in fuses, you were always supposed to have those little reject-washers in them so you couldn't put in a higher-rated fuse. 

(Of course, if they were changeable/insertable/removable rather than fixed-type sockets, that presents a bit of an issue even when "properly" installed from the beginning....)

[james_s]

That is why with the screw-in fuses, you were always supposed to have those little reject-washers in them so you couldn't put in a higher-rated fuse. 

(Of course, if they were changeable/insertable/removable rather than fixed-type sockets, that presents a bit of an issue even when "properly" installed from the beginning....)

I remember they made "Type S" fuses that had an adapter that screwed in and then locked in the socket which made it impossible to install the wrong size plug fuse. Most of them though were just ordinary Edison screw base fuses that were completely interchangeable. I saw a few type S fuses but they were never common as far as I could tell.

[carp.andrei]

Hey guys!

Thank you for all the answers. Indeed, the Romanian code allows both method of wiring (metal tube with individual conductors) or special fire resistant cables mounted directly on timber or through the studs.

I was curious how it was done in other parts of the world. Of course I'm gonna get someone with the proper qualifications to do the wiring, but for my peace of mind I just wanted some more background on the topic.

But as far as I can tell, cables that run directly through studs and service spaces are often used, together with proper sizing of the cross-section and associated circuit breaker.

The local electricians are kinda' split in two... ones that swear by metal tubing and individual conductors and the ones that swear by flame resistant cables. And the ones that cling on metal tubbing are more numerous than the others...