For 90 V AC, you would need to check the voltage rating of the
connectors, too. Probably lower than that of the coax.
On 2026-02-27 18:22, Ralph McDiarmid wrote:
I find the phrase, “supplied by a transformer or other device that has
power-limiting characteristics” as unhelpful and unsatisfactory. A
quantity like, 100 VA, would clarify the requirement. The Code‑Making
Panels (CMP) and the Technical Correlating Committee (TCC) who create
the NFPA 70 document are supposed to know better.
For CATV using with inline amplifiers for signal leveling, the power
caried in the coax can be up to about 18 Vdc and 500 mA. If you’re
pushing 90 Vac on a coax, then you will need to look up the rated
voltage for that coax and whether that rating is regulated by 3rd
party. (e.g. UL or TUV or CSA ….) it would not be treated as Class 1,
2, or 3 as in signalling control, doorbells, and alarms system circuits.
Ralph
*From:*John Woodgate <[email protected]>
*Sent:* February 27, 2026 3:34 AM
*To:* [email protected]
*Subject:* Re: [PSES] CATV standard in USA
'Not over 60 V' does not allow 66 V. The limit implies 54.5 V ± 10 %.
On 2026-02-27 11:10, Boštjan Glavič wrote:
Dear experts,
I would again need your advice.
We are testing the product, that is supplied through remote CATV
network via coax cable. Manufacturer would like to put on the
product 90Vac rating.
My questions are:
- what voltages are actually used in USA for CATV? In EU we
normally use max 65Vac.
- how is the supply voltage generated (what are requirements for
power sourcing equipment)?
- can supply voltage fluctuate, similar like ac mains voltage? For
normal AC mains we expect fluctuation +/-10%.
- should +/- tolerances to 90V be applied?
I found below text in NEC 2017, which says something about 60Vac.
Is this 60V fixed value or tolerances are allowed (like 66V)?
820.15 Power Limitations. Coaxial cable shall be permitted to
deliver power to equipment that is directly associated with the
radio frequency distribution system if the voltage is not over
60 volts and if the current is supplied by a transformer or other
device that has power-limiting characteristics.
Power shall be blocked from premises devices on the
network that are not intended to be powered via the coaxial
cable.
Thank you for your valuable support.
Best regards,
Boštjan
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