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Phil
Phil, Mechanical Engineer
Category: Electrical
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Experience:  Retired electrical contractor, 51 years experience.
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I am making / wiring a chandelier with 11 sockets, using 15Watt

Resolved Question:

I am making / wiring a chandelier with 11 sockets, using 15Watt 130V bulbs, in parallel (All 11 wires go up to the canopy and connect directly to the 120v source)
How do I make sure it's safe? Is this the equation I use?: P/E=I 1.375 amps??
How do I figure out the max wattage bulbs or do I need to wire them in series?
I am using 18gauge cotton covered twisted cord, I have stripped the cotton when it's in the canopy, is a little bit of it allowed to be there or do I need to cover every centimeter of the cotton with tape.
Submitted: 2 years ago.
Category: Electrical
Expert:  Phil replied 2 years ago.
All work must be permitted and inspected. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED. I must come and go. This is step One.

Hello
First its necessary to understand the electrical code on the issue.
here is a good link in that regard.

http://electrical.about.com/od/codesregulations/a/fixturewireratings.htm

Next are maximum ampacity ratings for the 18 gage wire... and that varies by type of wire, which is an unknown at this point.

beyond that is what someone else may do later, such as fit all 60 watt bulbs for instance. over loading the wire. The codes should be viewed as *minimal standards.

the installation of an overload will prevent damage and a possible fire if someone follows you with the wrong bulbs.

I would use 16 AWG THHN wire, its a bit stiff though... its made to withstand abrasion and heat.

here is some background
http://ecmweb.com/nec/code-basics/electric_conductor_size_matters/


The chart below sizes wire for longer runs.
http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity scroll down to the second chart which shows ampacity for #18 and #16 wire.. those are peak carrying capacities, not the constant load ratings which are 20% lower...

#18 wire with a 10 amp fuse would be safe.
#16 wire with a 12 amp fuse would accommodate the wrong bulbs to a greater degree.

Fixture wire sizes can be lighter, but doing it yourself, I would stay within these limits.


We keep going until all of your questions are answered.. Phil

Phil, Mechanical Engineer
Category: Electrical
Satisfied Customers: 5553
Experience: Retired electrical contractor, 51 years experience.
Phil and other Electrical Specialists are ready to help you
Customer: replied 2 years ago.
graphic

These are the wires I used:
http://www.sundialwire.com/2-conductor18-gaugegraygoldmarkerthreadtwistedcottonwire-bythespool.aspx

Should I switch to 16gauge of this type of wire if this is the decorative wire that people prefer?

The references you sent are great- I'm going to research it more.
So you suggest to put that line on an amp fuse that is appropriate for the wire gauge.

Since it's already wired with 18g- is lowering the amp fuse the only way to be safe?
I see on the wiki chart as you said #18 wire, 10 max, 20% less to a constate late rating would be 8amps. But I should put in a 10am fuse?

How does the length of wire affect the amperage limits - equation I should stick too? For example this chandelier is at 43" of cord, the next chandelier of 5 pendants is at 72" of cord.

In the future I have a 5 cluster pendant light to wire- how do I figure out the the safe way to wire this: to consider 5 at the 60 watt (even though it's too much) = 300watt/120V=2.5 amps : is that correct to calculate

Also here is a picture of inside the canopy. All 11 in parallel. Is this correct? get rid of the canvas? what am I doing wrong
many thanks!!!
graphic


Expert:  Phil replied 2 years ago.
Hello again, you are figuring it correctly.

The 10 amp fuse is rated for the maximum rated capacity of the wire because its a fuse, made to protect the wire from catching fire at amperage draws considerably above 10 amps.

The 100% duty rating of the wire at at 8 amps, does not require an 8 amp fuse... thats a sizing and applications limit number... but the wiring itself is built to stand the maximum...in the case of #18 wire thats 10 amps in this case.

regarding panel and fixture wiring, with much shorter runs, yes the wire can be sized even smaller.. but I do not recommend that for do it yourself projects... its better to be conservative, since the system is not receiving full electrical engineering review or meeting more stringent enclosure standards.

Regarding your mention of stripping off the fabric wire covering, thats beyond my ability to evaluate since I cannot see the wire or know its manufacturing specifications or the condition of the insulation etc.

However your junction box is metal with an apparently legal grounded cover, a 10 amp fuse fit into the line 1 common there should provide adequate protection... I would use a spade type fuse and fuse holder as available at auto supply stores.

if you wanted to be even more conservative you could of course fit a lighter fuse. a 6 or 8 amp fuse would work as long as the fuse was at least 30% over the calculated amps depending on the bulbs you fit.

If this does it for you, you can click the big green accept button, that way I get credit for my work, and you can continue tomorrow or months later on the same dime.

Thanks!




Customer: replied 2 years ago.
YOu're amazing!!

One last thing:
can you explain this:
"10 amp fuse fit into the line 1 common there should provide adequate protection... I would use a spade type fuse and fuse holder as available at auto supply stores."

I am not familiar with fuses. which would you recommend buying and how do you use it.

Many thanks!
Expert:  Phil replied 2 years ago.
The fuse is the yellow thing.

the fuses are different colors depending on the amp rating, do not go over 10 amps

http://www.google.com/imgres?q=automotiv e+blade+fuse+holder&hl=en&biw=991&bih=468&gbv=2&tbm=isch&tbnid=_KQgMctjJq8wWM:&imgrefurl=http://www.reuk.co.uk/buy-20A-FUSE.htm&docid=LSXRpXj1KmKvFM&imgurl=http://www.reuk.co.uk/shopImages/20a-fuse.jpg&w=280&h=224&ei=2NI6T8LcDuOPiAKowaCUDA&zoom=1&iact=hc&vpx=593&vpy=157&dur=2207&hovh=179&hovw=224&tx=143&ty=103&sig=110858023342844793875&page=2&tbnh=135&tbnw=187&start=4&ndsp=15&ved=1t:429,r:8,s:4



You can continue after you accept if you wish, days or even months later on the same dime

Thanks!
Expert:  Phil replied 2 years ago.
The fuse is the yellow thing. the fuses are different colors depending on the amp rating, do not go over 10 amps http://www.googl e.com/imgres?q=automotive+blade+fuse+holder&hl=en& ;biw=991&bih=468&gbv=2&tbm=isch&tbnid=_KQgMctjJq8wWM:&imgrefurl=http://www.reuk.co.uk/buy-20A-FUSE.htm&docid=LSXRpXj1KmKvFM&imgurl=http://www.reuk.co.uk/shopImages/20a-fuse.jpg&w=280&h=2 24&ei=2NI6T8LcDuOPiAKowaCUDA&zoom=1&iact=hc&vpx=593&vpy=157&dur=2207&hovh=179&hovw=224&tx=143&ty=103&sig=110858023342844793875&page=2&tbnh=135&tbnw=187&start=4&ndsp=15&ved=1t:429,r:8,s:4
You can continue after you accept if you wish, days or even months later on the same dime Thanks!

You do not want the one with the warning light, just the plain fuse holder and fuse, auto supplys carry them... be sure its rated on the package for 110 volts AC... virtually all of them are.

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