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Electronics => Projects, Designs, and Technical Stuff => Topic started by: carlossless on April 22, 2022, 07:50:01 pm

Title: UFH Control Wiring Question (230VAC->24VAC)
Post by: carlossless on April 22, 2022, 07:50:01 pm

Hey all,

I have been recently blessed with the opportunity to install some electrical underfloor heating controls for my relative's apartment after the original contractor flaked out on us. They bought all the parts, but weren't able to do that actual installation - in the end, I decided to do it myself.

The parts they bought (actuators and thermostats) are all made for 230VAC systems, but the wiring from the heating controls place to the thermostat locations in the rooms is all cat5e. Now, this immediately turned on some alarm bells in my brain - surely I am not going to run 230VAC over cat5e, but after calling the contractors I was told that it would be enough to tie 2 of the conductors together for that to be ok (honestly why not tie four at that point?).

Anyway, having not done this before and not having a strong desire to burn any houses down, I decided to (potentially) over-engineer the problem and decided to use 24VAC for the control circuit (which is the lowest voltage the thermostats also supported) and do 230VAC switching for the actuators with a separate array of relays.

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Since I am an amateur having worked mostly with low-voltage digital stuff, I am looking for opinions from the EE pros. Am I an idiot for doing this? Is this actually safer? Or have I missed some critical flaw here.

Thanks!

Title: Re: UFH Control Wiring Question (230VAC->24VAC)
Post by: tooki on April 23, 2022, 02:41:47 pm

I’m not an electrician, but a quick search says that Cat5 cable is rated for 100V maximum. The insulation isn’t designed for 230V (never mind any surges or spikes that could happen).

Imagine what your insurance company would do if your house caught fire and they found 230V connected via LAN cable… That’s if you survived the fire, that is…

I think your approach seems much smarter.

Title: Re: UFH Control Wiring Question (230VAC->24VAC)
Post by: themadhippy on April 23, 2022, 02:59:53 pm

Quote

but a quick search says that Cat5 cable is rated for 100V maximum. The insulation isn’t designed for 230V (never mind any surges or spikes that could happen).

you can find cat 5 cable with a 300 or 500v rating,however that's to allow it to be used were its installed alongside mains wiring to comply with the "insulated to the highest voltage present"  rule,and no way should it be used   for anything but extra low voltage