Can improper wiring actually cause a fire?

[Lew Hodgett]

If I was on the clock, probably.

If it was for myself, probably not (I like solder and shrink tubing).

Lew

[Charley]

Solder and shrink tubing are considered less safe than wire nuts for power wiring because they will both fail at relatively low elevated temperatures. A wire nut will continue to hold the wires tightly together until the wires get so hot that the insulation burns off of them. Wire nuts have been used safely and successfully in the electrical industry for over 75 years. The only place that I would not use them is in high vibration areas of machinery as they will shake loose over time. Split nuts or crimped on ring lugs that are bolted together and then heavily insulated with rubber tape followed by a layer of plastic tape is the solution for these locations such as motor connections, etc. Solder and shrink tubing is great for low current control circuits, but not for power.

[Doug Miller]

The insulation will burn off long before they get hot enough to melt solder, too.

The shrink tubing would be a Code violation unless it's specifically listed for use at the voltage and amperage of the circuit involved.

Apparently not in the UK :-)

[snip]

The National Electrical Code permits soldered joints, but requires them to be both mechanically and electrically secure *without* the solder. Nothing wrong with using solder in power wiring -- it just can't be the *only* thing holding the junction together.

[lwasserm]

I'm being somewhat facetious here, but what exactly is the benefit of adding the solder here?

[Doug Houseman]

solder helps with the movement of DC power thru the wires. It actually can hinder the movement of AC since AC moves on the surface of the wire.

If you do a good job with the wire nut (I highly recommend use of wire nuts to join wires running AC power) then solder is not recommended in any way. The use of Solder pre-dates the creation of wire nuts. I typically find it in high end houses from the late 1930's to the early

1950's.

Normally because it is a dissimilar metal to the wire itself, there is corrosion in the joint where it is used, when we take the joints apart.

[Doug Miller]

None that I'm aware of, other than possible psychological benefits to the electrician or the homeowner.

That provision is in the Code explicitly to prohibit the use of junctions in which solder is the main, or only, thing holding them together.

[Doug Miller]

I thought that effect occurred only at higher frequencies, in the neighborhood of 400Hz and up -- i.e. at 60Hz, AC is still moving mostly inside the conductor. No?

[Roy Smith]

I just refreshed what I used to know about skin effect by reading the wikipedia article about it

The executive summary is that for 60Hz, current flows in the outer 8mm of a conductor. This means that for a solid wire anything less than 16mm diameter (a bit heavier than 6/0 AWG), skin effect can be ignored. It's certainly a total non-issue for the sizes of wire likely to be found in your house.

[Doug Miller]

Thanks -- that's kinda what I thought, but I wasn't sure I was remembering that right.

[Markem]

The only advantage to soldering house wiring is that expansion and contraction of the wires will not loosen the connection. I have seen one house done this way, it had been the home of an electrician (connection made with wire nut, remove nut solder wires, replace nut, tape with electrical tape, the heat shrink over the nut with RTV sealing the heat shrink). The wiring was also in conduit as is the practice in Chicago, though it could have been romex, being it was Mc Henry county. Definitely a belt and suspenders fellow. Remember to check the connection to your devices and tighten them up. (Not that I do as I say, except at the panel)

Mark (sixoneeight) = 618

[Doug Miller]

That's not an issue with properly made splices using wire nuts, either. If it were, the Code wouldn't permit them.

[Markem]

Where in my story did you extrapolate that from.

If the wiring was done during the copper shortage in the 70's with aluminum wire it is a major issue.

Code allowed the use of the aluminum wire too.

Mark (sixoneeight) = 618

[Doug Miller]

From your reference to avoiding that issue being an "advantage to soldering house wiring".

Only if it was installed improperly. Note, also, that solder wouldn't fix

*that* problem...

You should be using the present tense, not the past: Code still does allow the use of aluminum wire. Properly installed aluminum wiring is not hazardous. The problem is that installing it properly is not nearly so easy as installing copper wiring properly. Aluminum wire installed using the same materials and techniques used for copper is dangerous as hell, but aluminum installed using materials and techniques that are appropriate and approved for aluminum is safe enough to satisfy the NFPA.

[Markem]

Given that most home owners do not know that it also must be maintained over "properly installed". A subdivision in Schaumburg Illinois has an much high than average electrical fire problem due to "properly installed" aluminum wire, so much so that insurers insist that the houses be rewired with copper before a new owner can get insurance or a mortgage.

It is hazardous to the bankers and insurance companies, and Cook county and Chicago no longer allow it for residences. But they still require conduit and wire nuts too.

Chicago the most grounded city in the states.

Mark (sixoneeight) = 618

[resrfglc]

"insurers insist that the houses be rewired "

Funny, I was told insurers don't get involved in wiring to codes etc. on this very listserv.

[Markem]

Not a code issue, it is a economic one, no insurance, no mortgage, no sale.

Mark

(sixoneeight) = 618

[Doug Miller]

Yes, I'm familiar with that phenomenon. We have a subdivision not far from my home in Indianapolis with the same problem. I have to wonder, though, just how "properly" it was actually installed -- lots and lots of homes were not done correctly from the get-go, even by professionals who should have known better. And of course over time, homeowners replace switches, receptacles, and light fixtures, probably in complete ignorance of the potential dangers. It would be interesting to see if anyone has ever determined whether the fires originated in the original wiring or in later modifications.

Yeah, Chicago has a "thing" about fires for some reason...

[Markem]

I helped a friend on a side job rewiring one of the houses, it was done to spec all through. But we did replace half of the devices as they showed evidence of arcing due to the expansion and contraction of the aluminum wire.

I do not see the NEC as eliminating hazards but mitigating the hazards, I read you saying " no hazard" my bad maybe?

NEC might have changed to since the middle 70s to address problems encountered.

Mark (sixoneeight) = 618

[Doug Miller]

Were they all Cu/Al rated?

No more yours than mine. I did say that, properly installed, it was safe enough to satisfy the NFPA. But I had omitted any mention of the need for periodic maintenance, which you correctly pointed out.

It probably has. The oldest Code books I have around are a 1999 NEC, and, for some reason, a 1987 Code Handbook. Oldest one I've ever actually used was

1984, and I've slept a time or two since then...

[Markem]

Yes, but the walls were under insulated (cheap housing). That points me to the temp swings of the seasons as a contributing factor in the problems seen there.

Mark (sixoneeight) = 618