Monoprice has SlimRun Cat6a Ethernet Cables on sale below when you apply corresponding promo codes (if applicable). Shipping is free. Thanks Discombobulated
TL;DR: For short patches these aren't bad despite the "experts" here going on about "but physics". (I've got an CompE degree too TYVM)
I assure you, they accounted for 'physics' when they wrote 802.3at Type2 "PoE+" and the resistance numbers you're quoting are actually incorrect to boot. How about we also look up the POE+ and cable specs?
- max cable resistance is 12.5 ohms
- max voltage drop is 7.5v (based on PSE vs PD)
- max power loss is 4.5w (based on PS vs PD)
MonoPrice lists: 37.6 ohms/100m so the 50' (15m) cable is 5.5 ohms.
22g/23g cat6 usually comes in ~9-9.5 ohms/100m
Calculate your run length + patch cord and decide accordingly. If thin patch cables are needed due to cable count, aesthetics, or other reasons make sure your total run is in spec.
e.g. 25m plenum cat6 + 2m patch = 3.13 ohms and is well with spec.
*Mic drop*
But wait... calculating for volts and then talking about power (watts)? Those are NOT the same thing/unit/measurement. Might as well say you've got a 18 gallon gas tank therefore your MPGs are better. If we want to work out the math for fun:
P(loss) = V(drop)*I
V(drop) = I*R
Substitute for V and the formula for power loss is I^2*R
- 600ma (0.6A) max @ 12.5 ohms max = 7.5V (which is exactly what the PoE spec calls for)
- Power loss would thus be 0.6^2*12.5 = 4.5w (which, shockingly, is exactly to spec)
And EXTRA ALSO - this is *only* for PoE delivery. It has NOTHING to do with attenuation which is *far* more relevant for 1G/10G runs. Folks having problems with these cables are almost certainly having signal issues, not PoE, and especially so if they've got longer runs near/at/over max spec.
very thin wires: 30AWG
recommend not using these for PoE and go instead with cable that has copper 23/24 AWG wires for PoE
For those wondering, thickness of wire increases as the gauge number decreases. It's counter intuitive. So, thought I'd mention. 30 is less thick than 24.
Sign up for a Slickdeals account to remove this ad.
It seems like it's a lot cheaper on amazon usually?
I just compared prices - for these particular sets of cables they are definitely cheaper on Monoprice as of now. I thought shipping would make them even out but I'm actually getting the rare free shipping from Monoprice for these sets.
Edit to add - I like these cables a lot, I have about a dozen of them now. They are nice and slim yet rugged. Not totally "lay flat" but not nearly as bad as most ethernet cables that keep that coil shape.
For those wondering, thickness of wire increases as the gauge number decreases. It's counter intuitive. So, thought I'd mention. 30 is less thick than 24.
recommend not using these for PoE and go instead with cable that has copper 23/24 AWG wires for PoE
Thanks for the heads up. Have you used these in a PoE situation with negative results? I actually have a pack of these in 1ft that I really like but I'm looking into adding a PoE switch for a couple devices and was wondering if I should move to some non-SlimRun cables for those.
Thanks for the heads up. Have you used these in a PoE situation with negative results? I actually have a pack of these in 1ft that I really like but I'm looking into adding a PoE switch for a couple devices and was wondering if I should move to some non-SlimRun cables for those.
They can work with poe but the range is limited. The top end brand that sells and certifies their cables that is not monoprice has like a maximum of 27 meters. But normal wires would be better in any case. It all depends on the device though. If it is a low power device you can get away with it.
Thanks for the heads up. Have you used these in a PoE situation with negative results? I actually have a pack of these in 1ft that I really like but I'm looking into adding a PoE switch for a couple devices and was wondering if I should move to some non-SlimRun cables for those.
Hi elmedico27
Physics
The ability of a wire to transmit power is based on the surface area, the smaller the diameter of the wire the higher the resistance, heat, power loss - which means less efficiency and less distance the cable can run.
83 Comments
Your comment cannot be blank.
Featured Comments
I assure you, they accounted for 'physics' when they wrote 802.3at Type2 "PoE+" and the resistance numbers you're quoting are actually incorrect to boot. How about we also look up the POE+ and cable specs?
- max cable resistance is 12.5 ohms
- max voltage drop is 7.5v (based on PSE vs PD)
- max power loss is 4.5w (based on PS vs PD)
MonoPrice lists: 37.6 ohms/100m so the 50' (15m) cable is 5.5 ohms.
22g/23g cat6 usually comes in ~9-9.5 ohms/100m
Calculate your run length + patch cord and decide accordingly. If thin patch cables are needed due to cable count, aesthetics, or other reasons make sure your total run is in spec.
e.g. 25m plenum cat6 + 2m patch = 3.13 ohms and is well with spec.
*Mic drop*
But wait... calculating for volts and then talking about power (watts)? Those are NOT the same thing/unit/measurement. Might as well say you've got a 18 gallon gas tank therefore your MPGs are better. If we want to work out the math for fun:
P(loss) = V(drop)*I
V(drop) = I*R
Substitute for V and the formula for power loss is I^2*R
- 600ma (0.6A) max @ 12.5 ohms max = 7.5V (which is exactly what the PoE spec calls for)
- Power loss would thus be 0.6^2*12.5 = 4.5w (which, shockingly, is exactly to spec)
And EXTRA ALSO - this is *only* for PoE delivery. It has NOTHING to do with attenuation which is *far* more relevant for 1G/10G runs. Folks having problems with these cables are almost certainly having signal issues, not PoE, and especially so if they've got longer runs near/at/over max spec.
recommend not using these for PoE and go instead with cable that has copper 23/24 AWG wires for PoE
Sign up for a Slickdeals account to remove this ad.
Edit to add - I like these cables a lot, I have about a dozen of them now. They are nice and slim yet rugged. Not totally "lay flat" but not nearly as bad as most ethernet cables that keep that coil shape.
Thanks OP, picked up two packs.
recommend not using these for PoE and go instead with cable that has copper 23/24 AWG wires for PoE
recommend not using these for PoE and go instead with cable that has copper 23/24 AWG wires for PoE
Sign up for a Slickdeals account to remove this ad.
They can work with poe but the range is limited. The top end brand that sells and certifies their cables that is not monoprice has like a maximum of 27 meters. But normal wires would be better in any case. It all depends on the device though. If it is a low power device you can get away with it.
Probably not good to run this wire under carpet.
Physics
The ability of a wire to transmit power is based on the surface area, the smaller the diameter of the wire the higher the resistance, heat, power loss - which means less efficiency and less distance the cable can run.
http://poe-world.com/Calculator/
Basically: you really do not want to use thin wires to transmit power