I had a small kitchen fire and the electrical wire behind the drywall in my kitchen melted. What is the best way to safely and legally (to code) rejoin the wire?
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10You should contact an electrician who can do this safely. Doing this wrong just results in another, possibly worse fire.– GManNickGCommented May 5, 2021 at 17:41
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23@GManNickG that could be the answer to every electrical question posted here. However, since this is a Do It Yourself site, we do try to help people learn how to do it properly and safely. Whether or not they chose to do so is entirely up to them and could, unfortunately, lead to a house fire if they choose to ignore the sound advice (often from licensed electricians) that is offered.– FreeManCommented May 5, 2021 at 17:46
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8@FreeMan I am well aware of the site. There's a pretty large gap between someone capable of electrical work asking about a subtle detail, and this question asking how to, quote, "rejoin" melted wire. You can pretend to live in the abstract world if you want, obviously for this person the best course of action is to get someone experienced to help.– GManNickGCommented May 5, 2021 at 18:06
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13"Rejoin" could mean "reconnect with solder at the point of melting", or it could mean "redo in a proper, code compliant, legal, safe way". Not everyone 'round here has an excellent command of the English language. Not even native English speakers. As of now, this has a very good answer. If the OP has questions on how to do what that answer recommends, there are loads of existing questions he could look at, or he could ask follow up questions. It's how we learn...– FreeManCommented May 5, 2021 at 18:12
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5Your wording suggests you're in the US, and that's assumed by at least one answer, but can you confirm? Different countries have different rules and different products.– Chris HCommented May 6, 2021 at 10:46
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5 Answers
The "best way" is to replace all the damaged wire.
Either completely (from where it starts and ends now) or by adding two junction boxes (which must remain accessible) where you can join the undamaged parts of the wire to new undamaged wire between the two junction boxes. If you can reach one end with new wire, you may only need one new junction box.
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19Frankly, it's not just the "best way", it's the "only way". Anything else is dangerous.– FreeManCommented May 5, 2021 at 17:46
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1If it's smaller gauges of NM cable,(but we don't know what size or type the damaged wire is from the question) some areas do approve of a type of splice for concealed use, but I don't trust them myself, and some areas also don't and specifically bar their use, so it may or may not be code legal depending where you are, and it's definitely not "best." But yes, replacing all the damaged wire is the only way. true.– EcnerwalCommented May 5, 2021 at 17:59
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2@FreeMan No, there's also "Call an electrician to do it for you", which is the only way to legally do it where I live: DIY electrical and plumbing work are illegal here. Commented May 7, 2021 at 4:14
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If you have access to the inside of the wall via an attic, you may be able to use what's left of the old wire to fish the new wire up into the attic. That might turn out to be less work than installing junction boxes and re-arranging your kitchen to keep them accessible.– btaCommented May 7, 2021 at 20:50
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@nick012000 Well I'm glad I don't live there lol. Home owners can do electrical work pretty much everywhere in the US. We're talking about splicing a wire. It's not rocket science and many of us do this at work all the time– NavinCommented May 30, 2021 at 21:02
All splices (except for the Tyco splice mentioned in kg333's answer) must be made inside junction boxes.
The whole junction box cover must remain accessible forever without needing tools to disassemble the building in any way (but unlike a subpanel it does not require 'working space maintained 24x7).
The undamaged cable must enter the junction box via a strain relief or grommet that is UL-listed for that cable type and size.
The sheath must extend at least 1/4" into the junction box (bonus points for a bit more and using that to mark where it goes)
The separated individual wires must have at least 6" of length inside the box
The wires must extend at least 3" beyond the finished wall surface, unless the box is big enough to work with both hands (e.g. a 10x10 box does not require this rule).
The number of wires in the box cannot exceed the "box fill limits" (vague rule of thumb: 2.25 cubic inches per wire, but grounds are "on sale 4 grounds for the price of 1).
The box CAN have receptacles or switches on its cover... however those themselves require a box fill allocation (2x the wire size attached to it)
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answered May 5, 2021 at 23:27
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3Note these rules vary a bit by area. In Canada grounds don't count and you add a wire for every two insulated wire connectors (wire nuts, leverlock, screw terminal, etc) (rounding down). For devices deeper than 1" you also have to deduct the volume of the device.– K HCommented May 6, 2021 at 9:33
Presuming the cable in your wall is non-metallic (NM), you can use an in-wall rated NM splice. Here's a datasheet of such a splice as an example (not a recommendation of this product in particular)
Keep in mind that such a device has to be rated for in-wall use, appropriately sized for the cable you use it on, and has to be allowed by local code: you can't just use wire-nuts or crimp connectors that aren't rated for in-wall, and some jurisdictions don't allow this type of splice.
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Certainly, the device needs to be appropriately sized and pass inspection to local code; I'll add those assumptions.– kg333Commented May 5, 2021 at 18:27
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Pretty sure those NM splices have to be 'fishable' to be code compliant. Commented May 5, 2021 at 21:51
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1NEC 334.40(B) was updated in 2014 to include "for repair wiring in existing buildings where the cable is concealed", so OK for that use in much of the US. As Ecnerwal said, there's almost no details in OP, but "wire behind the drywall" would meet that requirement.– kg333Commented May 6, 2021 at 13:28
As the question does not exclude the wiring being in the UK, I would use two sets of WAGOBOX that under UK regulations can be built into a wall when used with the correct wago connectors. New cable can be installed between the boxes.
Unless you definitely know that the cause of the "small kitchen fire" was not electrical you shouldn't be splicing any wires.
A proper electrical survey (at least for the relevant circuit) should be carried out first.
If you do just splice the two wires together, at least include a MCB in the circuit - even a fused socket is better than nothing!
