We had some 12 volt deck lighting installed on a deck job recently, he made up some splices under the deck with wire nuts and wrapped them in electrical tape.
The installer says this is kosher, seems like not a good idea to me…
what are your thoughts?
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Replies
Nah. No good.
Water will get into the splices and start oxidizing the copper. They'll fail sooner rather than later.
Any good installer will use silicone grease-filled wire nuts. They have a skirt abound the end to hold the grease in and keep dirt out.
There are two kinds, one rated for direct burial and the other not. Use the direct bury if the splice is going to be in contact with the earth. This is OK for low voltage systems (15V AC or lower). Use the non-DB if the splice is above ground or in a j-box (not required but sometimes done).
King isa good brand. They're expensive and one-use-only--once the wire nut has been used, ther's not enough grease in it to waterproof another splice. As far as using them, it's like a regular wire nut. Using the fine-stranded landscape lighting wire, twist the conductors together by hand, spin on the wirenut. Make sure that there's no exposed copper at the butt of the splice.
In a pinch, you could use a regular wirenut (on the big side for the combination of wires you're splicing) and put a squirt of siliconized latex caulk in the wirenut, then spin it on. If the caulk isn't oozing out of the end, squirt some more in around the wires. Then leave the splice alone whole the caulk sets up.
Good luck.
Cliff
Cliff,
Thanks a bunch. They will not be burried, but rather more or less suspended in under the deck. Should they be put into a box? or is the exterior wire nut enough.
Should the splice be wrapped in tape if not in a box or some sort of shrink wrap?
It's a 12V system if that matters.
No requirement to have 'em in a box. Sometimes it looks better, though.
I apply about 4 or 5 wraps of electrical tape around all the wires, about 6" back from the splice, to provide strain relief. Don't wrap the whole splice up in tape. All that does is hold water around the splice.
Heat-shrink tubing? Well, if I have a fixture in a tree and the fixture lead doesn't reach the ground, I use a non-insulated butt splice, dab the wires in noalox (conductive grease), and crimp it on, then use heat shrink, the kind with the adhesive inside. That splice is as good as the wire itself, and isn't as bulky as wirenuts. I used to do this; then I got smart and started ordering those fixtures from the factory with 25 foot leads.
The adhesive-filled heatshrink is very expensive, and it's time consuming to extend leads this way. For anyone who thinks this is overkill, I work for some very discerning clients, and having a splice fail in a few years, or having a couple of wirenuts visible on the trunk of a tree is just not acceptable. I'm talking jobs with hundreds of high-end fixtures (@ $125 per, materials cost only) and miles of #10 wire. It's nice to work outside sometimes.
Cheers,
Cliff
THank you again Cliff.
Cliff,
Un-related question, what is the difference between the $ .39 receptacles and the $5.00 receptacles.
Obviously it's the quality of the product, but what makes a quality receptacle?
$4.61What do they teach you over at Larryville.You need to go to a REAL SCHOOL.The $5 ones are commercial.If you want quality ones get the spec version. they run about $1.75 to $2.25 and come in 4 versions 15 and 20 amps and with and without backwire.CAP will probably have some more specifics.But a few things. Spec grade is rated for working over more insertion/withdraw ccycles than the residential grade. IIRC commercial is even higher.The spec uses stronger/larger contacts contacts.
The strap on the spec holds the receptacle better. The face plate on the spec is nylon and non-breakable.
"The face plate on the spec is nylon and non-breakable."
This is the thing I've noticed most often about the bargain bin receptacles...it's very easy to chip or break the front part. I have a couple of them in my house, and electrically they still work okay, but they all have chunks broken out of the front from someone yanking out a power cord.
Replacing them is on this winter's to-do list.
A high quality receptacle (like $5 per) has:
-- a full-length mounting strap of heavy gage steel
-- high quality plastic
-- big rivets that are well-set, holding the body to the strap
-- inside, two heavy gage contact strips to grip each blade of the plug (some people don't like top-quality receptacles in a house, because they think it's too hard to insert and remove a plug)
-- more consistent dimensions so that the receptalce face closely matchs the wallplate
-- quality terminal screws, and usually side wiring via screw-tightened pressure plate
-- a grounding terminal screw that is part of the body, not hanging out there on a wimpy sheetmetal tab that deforms when you tighten the terminal screw
--better quality mounting screws (the heads of the strap screws of the 59 cent receptacles strip out real easy, and I've seen some that are a bit undersize, so they're a little loose in the box)
Terminology is non-standard, but where I live and work, it goes something like this:
resi-grade -- 59 cents. O.K. if it's never going to be used, or if the homeowner expects to redecorate in a few years and replace all the devices (receptacles and switches) to match the new color scheme.
spec grade -- $1.75. Good quality, ought to last 20 years. Even when the budget allows only resi-grade in most of the house, I lobby for spec grade receps for the kitchen counter plugs (that aren't GFIs but are GFI-protected). The heavy power demand of toaster or microwave can cook a resi-grade recep in a few years.
commercial grade -- $6.00. People will complain about how hard it is to plug in and unplug stuff.
hospital grade -- $12. Stringent criteria for plug grip and so on.
audiophile grade -- $150 dollars for a duplex receptacle. Gold plated contacts (supposedly). The hard-core audiophile is an interesting animal.
NASA grade -- well, I dunno, but I'm guessing that there are power connectors for the shuttle and the space station, and I'm sure the price is sky-high. It'd be a pisser if the cord for your polarizing defrabulator pulled out in the middle of a spacewalk...
Cliff
When I built my shop, I found hospital grade receptacles on Ebay for very reasonable prices. They happened to be bright red which might not make them the ideal choice inside the house, but a great answer for the shop.
I wouldn't use silicone/latex caulk -- when it hardens it will offer little protection against corrosion. Better to use petroleum jelly, or silicone auto electric grease.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
Have you got much experience using siliconized latex caulk to waterproof a direct bury low-v splice? I've tried it, and it's worked.
Keep out the air and water, and there's no corrosion.
Unless I'm missing something...
I'll admit that I haven't, and the caulk is likely better than nothing (so long as it doesn't react with the copper and actually cause corrosion), but I'd rather have the grease.
(One could then use caulk on the outside to keep the grease in place.)
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
Edited 11/9/2006 6:38 am by DanH
I was going to swoop in and quote some advice from Cliff...but the man himself beat me to it! Didn't know you were lurking around here these days Cliff
Justin Fink - FHB Editorial
Your Friendly Neighborhood Moderator
Everything I've seen in the electrical code, regarding wiring, pretty much treats low voltage the same as 110 voltage. If it wouldn't pass for normal wiring then it's not going to pass low voltage either.
If the source is current limited to under 200mA (IIRC, may be differnt number now), then low voltage can be about anything.
However, in own house all the non-plated -low voltage control power circuits are soldered - primarily for the corrosion and poor connection problem mentioned earlier.
"Everything I've seen in the electrical code, regarding wiring, pretty much treats low voltage the same as 110 voltage. If it wouldn't pass for normal wiring then it's not going to pass low voltage either."
Low voltage wiring (less than 50 volts, either ac or dc) is covered in article 720 of the NEC. This section is only about a half page long, and all it says about installation is circuits "shall be installed in a neat and workmanlike manner." For non-hazardous areas, there are no specific mentions of conduit, junction boxes or any of that.
Thanks for sending the code section #, I'm always interested to learn more.
Section 720-11 Mechanical Execution of Work- circuits operating at less than 50 volts shall be installed in a neat and workmanlike manner. Cables shall be supported by the building structure in such a manner that the cable will not be damaged by normal building use. Section 720-2 Hazardous (Classified) Locations- Installations coming within the scope of the article and installed in hazardous (classified) locations shall also comply with the appropriate provisions of Article 500 through 517Another section of interest here is Section 411 ( Lighting systems less than 30 volts). In short that section says ( sec 411-3) the lighting system shall be listed for the purpose used and (sec 411-4) says that low voltage lighting systems less than 30 volts cannot be concealed or extend through building walls unless using the wiring methods already outlined in Chapter 3 ( normal 110 volt wiring methods). Section 411-4 then goes on to say that low voltage wiring systems shall not be used within 10 feet of pools, spas, fountains, or similar wet locations except as outlined in Article 680 (again normal 110 house branch circuit rules). Sounds like I was only partially right but partially wrong too. Again, thanks for pointing me to section # 720 . The wording "Workmanlike Manner" certainly leaves a lot open to interpretation. One man's crappy wiring is another man's example of craftsmanship. Who's to judge here?
> Who's to judge here?The inspector. Though generally LV exterior lighting does not require an inspection.But "workmanlike manner" is standard terminology in contracts and the like, and presumably has an established legal meaning.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
With a 12 volt system there's no need for connections to be in a box. You do need to prevent shorting, however, both because of the slight fire hazard and because shorting will burn out the transformer. This primarily means that the connections must be mechanically protected from pulling apart (since when you pull apart such a connection the two wires tend to touch).
Simplest way to protect from pulling apart is to tape the two pieces of cable together securely, leaving slack at the splice, then secure the whole thing with staples, etc.
The bigger problem is poor connections. At 12V you need ten times as much current for the same power, so the connections need to carry a lot of current, and a little resistance will torpedo the whole setup. Wire nuts are probably better than the clamp-on connectors they sell for low-voltage wiring, but either one will corrode in the weather, so using a contact grease is a good idea.
With a 12 volt system there's no need for connections to be in a box. You do need to prevent shorting, however, both because of the slight fire hazard and because shorting will burn out the transformer. This primarily means that the connections must be mechanically protected from pulling apart (since when you pull apart such a connection the two wires tend to touch).
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Guess I'm the unlucky one when it comes to slight fire hazard. Cat knocked a head off a path light and shorted the system... Overheat protector was doa on transformer that was plugged in next to main electric panel in garage.
Needless to say I'm not an advocate of low voltage outdoor lighting.
"Needless to say I'm not an advocate of low voltage outdoor lighting."What about cats?
It would appear that cats have an unknown calling in the quality control of low voltage lighting... or designers of low voltage transformers should be euthanized .
Jury's still out.
Edited 11/9/2006 8:23 pm ET by sledgehammer
Edited 11/9/2006 8:24 pm ET by sledgehammer
I had a really bad experience with chalked wire nuts. It turns out that some chalking materials give off acetic acid when it cures. Since the acid is trapped inside the wire nut, it goes to work on the copper wires. They were very badly corroded and I had to find and replace every electrical connection that my landscaping contractor made in a 1 acre yard...What a pain. I would be very careful about using chalk. I remade the connections with wire nuts and some silicon grease and they worked for years without a problem.
That must have been RTV silicon.That is a common problem for electronics.There have long been Neutral Cure silicons, that did not have that problem, for industrial use.I believe that the new GE Silicon II caulks are neutral cure.
Thanks for the heads up