Electrical wiring for Timber Frame House - Page 1
Forum section: electronics / beginners

author: carp.andrei
author_rank: Newbie
timestamp: April 12, 2021, 12:52:56 pm
content: Hello eevbloggers!I need your oppinion in the following matter:I'm planning to build a timber frame house, and this building system is not very well known in my country, in Romania.So, I was wondering how is the electrical wiring done elsewhere, where this system is more widely used.From the company that is going to install the electrical wiring I got two options: metal tubing (metallic kopex?) with individual wires, or a special, fire retardant, cable (don't remember the code by heart) to be use without any additional protection.Can you please share some of the practices used in your houses, for those who have Timber frame houses?I'm still searching through the Romanian regulations on this topic, but I can't say I'm much wiser now.So, your help is much appreciated!Thank you in advance!

author: jpanhalt
author_rank: Super Contributor
timestamp: April 12, 2021, 01:16:44 pm
content: This Old House is an American public TV series (https://www.thisoldhouse.com/concord-barn). Seasons 11 and 30 dealt with a barn rebuild and a pre-FAB timber-frame house, respectively. I saw the first in its entirety and don't recall anything specific about electrical wiring. There may be other shows in the series that address adding electrical wiring to solid walls.Timber frame, including the barn reconstruction, and log construction present similar challenges for in-wall electrical service. My current home is log up to the second floor. Feeds to the first floor are either from the basement or roof and drilled through the logs. The interior walls are all tongue and groove fitted wood. Of course, any add-on circuits after construction are difficult to do.In the US, surface wiring conduits are available and are more attractive and more easily modified than rigid conduit or EMT. I do not like any flexible cable (e.g., Romax) if it is exposed.As you suggest, whatever you do must comply with applicable codes. One thing worthy to consider: Anything with wood timbers will make noises as the timber dries out and develops cracks. As an epilogue to the barn show, This Old House revisited the owners several years later. They mentioned overall satisfaction and being occasionally surprised by the noise.

author: hexreader
author_rank: Frequent Contributor
timestamp: April 12, 2021, 01:22:05 pm
content: Disclaimer: I am no expert...As far as I know there is no difference in code for Timber frame vs traditional construction in UK.Maybe there is some difference in Romania. I think you need expert advice from somebody qualified in your country, not opinions from random forum members.

author: mvs
author_rank: Frequent Contributor
timestamp: April 12, 2021, 02:04:16 pm
content: Quote from: carp.andrei on April 12, 2021, 12:52:56 pmMetal tubing is not that oft used in residential houses nowadays. NYM-J cable or individual H07V-U wires in a flex plastic tube are more common, at least in Germany.

author: madires
author_rank: Super Contributor
timestamp: April 12, 2021, 02:15:58 pm
content: NYM-J cable and pattress boxes for switches, sockets and room distribution.

author: CaptDon
author_rank: Super Contributor
timestamp: April 12, 2021, 02:23:45 pm
content: 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.

author: themadhippy
author_rank: Super Contributor
timestamp: April 12, 2021, 02:39:05 pm
content: QuoteThe 2 main types in the uk are pyro/micc or fp2000, fp2000 is much easier to work with and doesn't require specialist tools ,but it doesn't offer as much mechanical protection as pyro.

author: wizard69
author_rank: Super Contributor
timestamp: April 13, 2021, 11:47:53 am
content: Timber framing isn't really the problem here, it is how the walls are constructed that will cause you the most grief. Some Timber frames use pre constructed wall panels that may or may not have ready made provisions for electrical. Some may use walls built up in a more conventional manner, which means plenty of time to install the electrical hardware. It would not be unheard of the have a combo of the two, especially if interior walls are considered.I think the key here is planning. If you are going with large pre fab'ed panels you will want to have the fabricator provide provisions for the electrics if at all possible.There are a lot of other considerations too, for example will the house have a cellar or crawl space or perhaps just a slab. If cellar is it expected to be a finished cellar or just a utility space. In other words there are all sorts of questions to be asked and answers considered. A timber framed house with a cellar would allow for fairly easy install of electrics (depends upon the specifics of the installation) even in a house built with prefabbed walls with no electrical provisions. Outlets for example would be feed from the cellar up into the wall. The electrician could handle it like "old work" using the tools for that type of installation.In some case you may need to embrace conduit and wire ways. Follow code but generally you will want conduit or wire ways everywhere the wiring will be exposed.running out of battery but hopefully this gives you insight.

author: tkamiya
author_rank: Super Contributor
timestamp: April 14, 2021, 02:11:36 pm
content: Electrical code/regulations are different in different parts of the world. In US, it's different from state to state. Unless you have Romanian rule book, you are taking a big risk. I'm almost inclined to say hire someone to get it done. Or consult/hire someone locally and work with him/her.I do have an electrician license from Japan.

author: tooki
author_rank: Super Contributor
timestamp: April 14, 2021, 03:46:04 pm
content: Quote from: carp.andrei on April 12, 2021, 12:52:56 pmBear in mind that while there is certainly plenty of knowledge on this topic here on eevblog, this is anelectronicsforum, not anelectricians’forum (they’re different vocations that have a relatively small amount of overlap in practice). So an electricians forum or the electrical section of a builders forum might get you better information.As far as what you’re allowed to do, as others have said, the regulations vary a lot from country to country anyway, so your very best bet is to find the website where your country’s electricians hang out.

author: vad
author_rank: Frequent Contributor
timestamp: April 14, 2021, 10:06:55 pm
content: One thing that distinguishes timber frame houses from masonry buildings is that the timber houses get easily on fire and burn down really fast.Electricity is one of the most common causes of residential house fires.Therefore, I strongly recommend hiring licensed electrician who has knowledge of local electrical/fire codes, and has experience in wiring timber frame houses.

author: MadScientist
author_rank: Frequent Contributor
timestamp: April 14, 2021, 10:21:29 pm
content: goggle "romania house wiring regulations" , my second search item was a EU copy in english of 2010 regs

author: james_s
author_rank: Super Contributor
timestamp: April 14, 2021, 10:24:52 pm
content: Refer to local electrical and building codes first, you're going to have to follow that no matter what. Then come here and post specific questions, along with what the code says and we can try to advise you. I have a lot of wiring experience but it is USA-centric, and there's a good chance that if showed you the way I do something, it wouldn't be legal there.

author: vad
author_rank: Frequent Contributor
timestamp: April 14, 2021, 10:28:29 pm
content: Having said that, in the United States both individual THHN wires in steel metal conduits, and Romex cables are permitted for residential wiring, as long as all applicable National Electrical Code and local state requirements are met. In most places DIY wiring by a person who does not carry Electrician’s license is against the Code.

author: james_s
author_rank: Super Contributor
timestamp: April 14, 2021, 10:29:59 pm
content: Quote from: vad on April 14, 2021, 10:28:29 pmFortunately it's perfectly legal here for a homeowner to do their own wiring, licensed or not. They still have to obtain a permit and have it inspected though, it has to follow all the same rules as it would if done by a licensed professional.

author: Bud
author_rank: Super Contributor
timestamp: April 14, 2021, 10:35:38 pm
content: If you want to understand how it is done in North America, download and browse a copy of National Electrical Code (NEC) or Canadian Electrical Code book.

author: wizard69
author_rank: Super Contributor
timestamp: April 15, 2021, 01:33:48 am
content: Quote from: james_s on April 14, 2021, 10:29:59 pmEven this varies a lot from region to region, that is what is required with respect to licensing and DIY work.

author: themadhippy
author_rank: Super Contributor
timestamp: April 15, 2021, 02:23:00 am
content: QuoteAnd to see how the uk is supposed to do it just shell out 70'ish quid for the regs,then chuck in the onsite guide and dont forget your guide to the building regs,you might just get change from £100 for those 3,but dont become to attached to them,as by the time you've finished reading them they'll have issued a new amended edition

author: Monkeh
author_rank: Super Contributor
timestamp: April 15, 2021, 02:45:50 am
content: Quote from: themadhippy on April 15, 2021, 02:23:00 amDon't forget to buy the other couple of dozen standards BS7671 makes reference to, by the time you're done you might have change from three grand.

author: james_s
author_rank: Super Contributor
timestamp: April 15, 2021, 05:06:27 am
content: I read the original post again and it sounds like you're considering one of two different methods that I assume both pass code where you are?Here 99% of houses are wired with Romex, a trade name for cable consisting of 2 or more conductors and a safety ground wire inside a vinyl jacket. It is run directly through holes in the wall studs with metal nail stop plates installed over the spots where it passes through the studs. Commercial buildings typically use metal conduit holding individual conductors. Occasionally you see raceways which are a type of surface mounted conduit but it is mostly for retrofit work and things like running wire along an exposed wooden beam, it was a lot more common in the past.If I were building a house from the ground up I would seriously consider using conduit for all the wiring, it is wonderful to work with and makes it so much easier to add to or modify the system later on. It's a lot more expensive and labor intensive to install though so it's very rare in residential construction although I have seen it in condo and apartment buildings and my mother's house was previously owned by a commercial electrician and he did a lot of the wiring in that style.

author: twospoons
author_rank: Frequent Contributor
timestamp: April 15, 2021, 09:24:31 am
content: Here in NZ probably 95% of our houses use timber framing. All the wiring is pvc covered copper cable, in 2.5mm^2 copper for 10A power outlet circuits (on 15A breakers) and 1mm^2 for lighting. The cable is usually run through the ceiling and wall cavities without using conduit of any sort.For reference we use a 230V 50Hz earthed neutral system, so each cable has a phase, neutral and earth wire.

author: Siwastaja
author_rank: Super Contributor
timestamp: April 15, 2021, 03:15:14 pm
content: Normal PVC insulated wiring inside flexible plastic tubing. Of course using products designed and certified for this.There is no need for special fire-proof materials, nor they are required almost anywhere AFAIK. This is because properly sizedand fusedwiring just simply has no mechanism to overheat and set things on fire. Note though that law requires certified professionals to do the planning and perform the installations.The key is to understand that the distribution box fuse size defines the copper gauge, this is a simple table lookup. Larger wire area is required when the wiring is run inside thermal insulation materials.Note that the required cross-sectional areas are quite a bit more than the classical "rules of thumb", because first, fuses are not precision devices so a 16A fused circuit can carry up to 24A pretty much indefinitely, and 32A for quite some time (an hour, maybe), and then again, a typical house wiring consists of first PVC insulation around the wires, then another 1-2 layers of PVC outer sleeve, then air gap, then the flexible cable conduit, then more or less thermally insulating building materials. And it needs to last for decades without degradation so basically the PVC has to keep below about 60 degC. This is why 2.5mm^2 is very typical even for the circuits using smallest sensible fuse sizes.

author: Monkeh
author_rank: Super Contributor
timestamp: April 15, 2021, 03:35:58 pm
content: Quote from: Siwastaja on April 15, 2021, 03:15:14 pmThankfully, 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.

author: Gyro
author_rank: Super Contributor
timestamp: April 15, 2021, 04:03:47 pm
content: Quote from: Monkeh on April 15, 2021, 03:35:58 pmI 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!

author: themadhippy
author_rank: Super Contributor
timestamp: April 15, 2021, 04:20:32 pm
content: Quotewho said? rewirable fuses are still fairly widespread , the current regs even has a correction factor for them.

author: Monkeh
author_rank: Super Contributor
timestamp: April 15, 2021, 04:35:54 pm
content: Quote from: themadhippy on April 15, 2021, 04:20:32 pmAnd do you go around doing new domestic installs with them?

author: james_s
author_rank: Super Contributor
timestamp: April 15, 2021, 07:34:04 pm
content: Quote from: Gyro on April 15, 2021, 04:03:47 pmThat 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.

author: geggi1
author_rank: Frequent Contributor
timestamp: April 15, 2021, 11:22:31 pm
content: 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

author: tooki
author_rank: Super Contributor
timestamp: April 24, 2021, 10:03:42 am
content: Quote from: james_s on April 15, 2021, 07:34:04 pmCircuit breakers containtwotriggers: 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.

author: Gyro
author_rank: Super Contributor
timestamp: April 24, 2021, 10:19:00 am
content: Quote from: tooki on April 24, 2021, 10:03:42 amWell, instantly apart from the mechanical inertia! In the Wylex rewireable fuse vsRCDMCB video I referenced, in a direct short situation, the fuse blew and theRCDMCB didn't have time to trip, even on the electromagnet.

author: Siwastaja
author_rank: Super Contributor
timestamp: April 24, 2021, 01:03:19 pm
content: 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.

author: wizard69
author_rank: Super Contributor
timestamp: April 24, 2021, 05:36:47 pm
content: 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.Quote from: Siwastaja on April 24, 2021, 01:03:19 pm

author: Stray Electron
author_rank: Super Contributor
timestamp: April 24, 2021, 06:22:21 pm
content: Quote from: CaptDon on April 12, 2021, 02:23:45 pmThestabtype connections to electrical outlets and switches have been the source ofmanyhouse 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!

author: Stray Electron
author_rank: Super Contributor
timestamp: April 24, 2021, 06:31:53 pm
content: Quote from: vad on April 14, 2021, 10:28:29 pmWhere? 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.

author: Stray Electron
author_rank: Super Contributor
timestamp: April 24, 2021, 07:06:38 pm
content: Quote from: vad on April 14, 2021, 10:06:55 pmThat'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 seenmanytotally 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 practicesscrupulously. 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 doessupportcombustion! 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.

author: themadhippy
author_rank: Super Contributor
timestamp: April 24, 2021, 07:18:09 pm
content: Quoteyoud 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

author: Jwillis
author_rank: Super Contributor
timestamp: April 25, 2021, 08:49:15 am
content: 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 .

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 25, 2021, 12:21:58 pm
content: Quote from: Stray Electron on April 24, 2021, 07:06:38 pmFor 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.

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2021, 06:33:56 pm
content: Quote from: themadhippy on April 24, 2021, 07:18:09 pmWe 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.

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2021, 06:36:26 pm
content: Quote from: Ed.Kloonk on April 25, 2021, 12:21:58 pmWe 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.

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2021, 06:56:24 pm
content: Quote from: Siwastaja on April 24, 2021, 01:03:19 pmIMO 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.

author: drussell
author_rank: Super Contributor
timestamp: April 25, 2021, 07:02:57 pm
content: Quote from: james_s on April 25, 2021, 06:56:24 pmThat is why with the screw-in fuses, you were alwayssupposedto 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....)

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2021, 07:08:57 pm
content: Quote from: drussell on April 25, 2021, 07:02:57 pmI 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.

author: carp.andrei
author_rank: Newbie
timestamp: April 28, 2021, 02:11:02 pm
content: 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...