Where to get flexible 2 core power cable?
Posted 15 December 2012 - 06:23 PM
I've seen this question asked a while ago, but I couldn't see any conclusive answer.
I'm looking for cable to use to make custom length leads for tidy supply to dew heater strips, and other 12V astro devices such as DSC controllers etc.
- black / dark grey
- flexible, including at lowish temperatures (say -5*C or 20F) NOT "plasticky"
- no more than 5mm or 3/16" in diameter
- capable of handling 10A, not in a big bundle (18 AWG?)
- a continuous outer jacket (not "zip" wire)
- available in USA (with shipping to Europe)/ Europe in non-industrial quantities (e.g. <10m)
The cable that Kendrick Astro use on their dew heater strips is great, as is Astro-Physics cable for mount power and servo motors. AP say on their usergroup that they import it from Asia if I remember right. I'm loathe to cut the original cables, unless I've got a replacement.
Polar Wire Products Inc. has previously been suggested here, but I can't find cable meeting the above criteria. Difficult to find something suitable with Google searching.
I can't be the only one here wanting the stuff Can any of you suggest a source?
Posted 15 December 2012 - 11:06 PM
Posted 16 December 2012 - 12:22 AM
It is a small diameter cable with two sets of twisted pair wire in it. The wires are rather thin, so I paired them up and used two for the positive and two for the negative to handle a bit more current.
The cable is only about 3/16ths in diameter, and one thing I really love about it is that after you uncoil it, it lays flat on the ground. It is very pliable but coils and uncoils easily.
I am really sorry that I can't tell you what it is called, but I suspect that because of the twisted pairs, it is something like telephone cord. The kind you used to find going to the old style wall jacks.
Excellent stuff, but I doubt that it would carry more than 5 or 6 amps, but I run a CGE and a C14 dew heater off of mine and it doesn't show signs of getting hot.
And it was dirt cheap. I think I bought 25 feet for about $5.
I think that this is the same stuff...
Posted 16 December 2012 - 12:28 AM
But I have been using the two pair for several years running my CGE and dew strip and have had no issues.
Posted 16 December 2012 - 03:14 AM
click here for parts express mic cable
Posted 16 December 2012 - 10:07 AM
I'm curious as to why you have so many criteria for the cable. It seems like you've over-constrained your choices to the point where it will be impossible to meet them all.
It seems like the most important considerations are that it is pliable when cold, and can handle 10 amps. Is that correct?
If the other criteria are truly important, maybe it would help to explain what you're trying to achieve. In other words, why black vs. white? Is it just an esthetic choice, or is there some other reason? I personally find white better because it's easier to see and less likely to trip over in the dark. What's the aversion to zip cable? Most heavy gauge cable comes in zip-style and allow that would provide a lot more options.
For example, I purchased some high end speaker cable recently for my home audio setup. When I received it, I found it was VERY flexible and stayed so at low temperatures so I started using it for my astro power cables. However, it is white and is zip type cable. Here's a link
It looks very ordinary from the pictures, but in person it looks and feels like a very high quality, very flexible cable.
Posted 16 December 2012 - 04:40 PM
Posted 16 December 2012 - 06:26 PM
I've looked in the directions you pointed me, and here are my findings, which might save others the time spent searching
This looks the best one from MC, and looks promising
Neoprene rubber-jacket cords
Black SJOOW 300 VAC Service Cord 18/2 AWG, .29" OD
part number 7422K2
sold in these lengths: 10, 25, 50, 100, 250ft, at 54c a foot
Nothing here at all - no cables
3. Old vacuum cleaners
Good idea, but a bit on the heavy bulky side, not sure about low temperature performance, and being used, not smart looking to go with the rest of my gear. (Yes, I'm particular about it )
The idea is good though - option 1 is "service cord" - used for power tools etc.
4. Regular old hardware stores
Hmmm. Not here in London. They just have mainstream stuff, and small selections. What we're looking for here is quite specialist, and most normally sold to manufacturers of electronic devices, not the average bloke for wiring something at home.
5. twisted pair wires, pliable (e.g. Fry's Electronics)
Thanks very much for the recommendation. I should be able to find twisted pair cable locally to try out. Do you think it would flex in the cold - depends on the outer insulation material, I guess?
6. microphone cable (e.g. Parts Express)
Thanks. I'd been looking at this previously, and it sounded like it would be nice and flexible. I was doubtful about its current carrying capability, which is where your positive experience helps! Great tip!
7. Too strict criteria? Why black?
Black is just for aesthetics. Yes, I'm a bit fussy. Bright blue wires for example, would just spoil the look of the beautiful astro gear The other criteria though, seem perfectly reasonable to me. This stuff exists (Kendrick dew heater bands, AP power and motor cables) - I just don't know where to get it.
8. Speaker cable, zip wire
Yep, maybe worth a shot. High end speaker wire tends to be pricey in my experience. I've just checked out mine, and yes, it seems quite flexy, but it's bulky. Good tip.
9. Silicone hobby wire, and a man who agrees with me
Yep, I think I know the silicone wire you mean - I used some heavy gauge stuff to wire a power amp in a motorhome. Lovely and flexy. That's exactly what I'd like in a twin code configuration.
Thanks again for all the tips. I'm going to look at SJOOW (see my next post for the codes I learnt today!) and mic wire first. And I'll let you know how I get on!
Posted 16 December 2012 - 06:33 PM
S = Stranded (or Service Wire)
J = Junior Service (300 Volt). If no "J" is in the wire type, then it is a hard service (600 Volt).
T = Thermoplastic. If no "T" is in the wire type, then it has a rubber jacket.
O = Oil-Resistant Compound
W = Weather-Resistant Compound
V = Vacuum - as in vacuum cleaner. This is a small O.D. jacketed wire, very flexible and initially used for vacuum cleaners but now used on many different types of products. Available only in 18 AWG.
SV = Stranded Vacuum Rubber Jacketed (NO "T")
SJT = Stranded Junior Thermoplastic
SJTOW = Stranded Junior Thermoplastic, Oil and Weather resistant for UL and CSA.
S Extra hard service flexible cord for general use at 600 volts,
rated at 60° C. Rubber insulated and jacketed.
Extra hard service flexible cord for general use at 600 volts,
rated at -58° F to +221°F. TPE thermoplastic elastomer
insulated and jacketed.
SEO Type SE, but also rated oil resistant.
SEOW-A Type SEO, but also rated for outdoor use at -58° F.
SEW-A Type SE, but additionally rated for outdoor use at -58° F.
SJ Hard service cord for general use at 300 volts, rated at 60°
C, rubber insulated and jacketed.
Hard service cord for general use at 300 volts, rated at -58°
F to +221° F, TPE thermoplastic elastomer insulated and
SJEO Type SJE, but rated as oil resistant.
SJEOW-A Type SJEO, but rated for outdoor use at -58° F.
SJEW-A Type SJE, but rated for outdoor use at -58° F.
SJO Type SJ, but rated oil resistant.
SJOW-A Type SJO, but rated for outdoor use at -30° F.rminology:
SJT Hard service cord for general use at 300 volts, rated -4° F to
+140° F, PVC thermoplastic insulated and jacketed.
SJTO Type SJT, but also rated oil resistant.
SJTOW-A Type SJTO, but rated for outdoor use at -31° F.
SJTW-A Type SJT, but rated or outdoor use at -31° F.
SO Type S, but also rated oil resistant.
SOW-A Type SO, but also rated for outdoor use at -31° F.
SPT-1 Thermoplastic parallel cord for light duty, 300 volts.
SPT-2 Type SPT-1, but heavier construction, 300 volts.
SPT-3 Type SPT-2, but heavier construction, 300 volts.
ST Extra hard service cord for general use at 600 volts, rated at
-4° F to +140° F, PVC thermoplastic insulated and jacketed.
STO Type ST, but also rated oil resistant.
STOW-A Type STO, but rated for outdoor use at -31° F.
STW-A Type ST, but rated for outdoor use at -31° F.
Vacuum cleaner cord, PVC thermoplastic insulated and
jacketed rated 300 volts, 18 AWG and 16 AWG only, two
T, TW, THN,
THHN, THWN Thermoplastic insulated wires. Building wires used for
Posted 16 December 2012 - 07:28 PM
Posted 16 December 2012 - 08:08 PM
Posted 16 January 2013 - 07:32 PM
Posted 17 January 2013 - 08:24 AM
Posted 17 January 2013 - 10:14 AM
Posted 17 January 2013 - 01:40 PM
Posted 17 January 2013 - 03:12 PM
Oh, and it wasn't located with the normal wiring...it was located in the deck lighting area. Deck lights are 12v systems......
Posted 17 January 2013 - 04:13 PM
Posted 17 January 2013 - 04:33 PM
Posted 17 January 2013 - 05:04 PM
Posted 17 January 2013 - 05:37 PM
Having thought about this some more, I think my original 10 amp criterion might be overkill to use all round, including for short runs to individual items like heater bands. Heavier gauge would be ideal for the main longer run to the battery or mains power supply to a dew heater controller or distribution box, from which lighter gauge could be used.
I reckon that mic cable would be fine for short runs, especially if making use of the shielding as one conductor and combining the signal cables as the other conductor.
I must actually try this and take some voltage measurements
Posted 20 January 2013 - 10:15 AM
This cable works PERFECTLY.
I ended up doing as John suggested and using the signal cables as the tip conductor and the shielding as the ring conductor, and everything worked beautifully. Resistance for the pair of signal cables (21 AWG each) tied together was 0.3 ohms over a 10' cable, while resistance for the shielding was 0.2 ohms.
I used the same Switchcraft 5 mm power connectors used by Astro-Physics and SBIG -- I had to enlarge the opening in the back of the plastic housing to 1/4" with a step drill bit in order for the rubber insulation to fit.
The cable is very flexible and the rubber insulation should tolerate the cold much better than the PVC on the power cables I'm replacing.
I love it when a plan comes together!