What a 20-amp circuit actually buys you

The question we get asked is “do I have enough power?” The question that can actually be answered is “what is the nameplate current of every device that will be running at the same time?” Until you have that list, nobody — including us — can tell you whether the circuit in that room is enough.

Start with the arithmetic that surprises people. A 20-amp branch circuit is not sized for 20 amps of steady draw. The National Electrical Code requires the overcurrent device and the conductors to be sized at 125 per cent of a continuous load, which puts the ceiling for continuous draw on a 20-amp circuit at 16 amps. That rule is NFPA 70, §§210.19(A) and 210.20(A). We are citing it rather than quoting it, because NFPA's free access is read-only and not reproducible — you can open the code yourself at no cost through NFPA's free access service, and your electrician will apply whichever edition your jurisdiction has adopted. Sixteen amps is the number to plan against.

The concentrator is the load you can actually look up

Oxygen concentrators publish real electrical figures, so this part is easy. CAIRE's operator manual for the NewLife Intensity 10 gives 120 VAC, 60 Hz, 6.0 amps, and a power consumption of 600 watts (NewLife Intensity 10 operator manual). Six amps of your sixteen, for the whole session, from one device.

Worth knowing that CAIRE's own documents do not fully agree with each other on the wattage. The cut sheet also says 600 W (NewLife specification sheet), while the product page says 590 W (CAIRE NewLife Intensity). Ten watts changes nothing about your circuit, and we are not going to average two published figures to invent a third. We mention it because it is a good habit: when two documents from one manufacturer disagree, the one that governs is the one shipped with the device.

The compressor is the load you usually cannot

Here the record thins out fast. OxyHealth publishes a requirement of “110-120V” for the Fortius 420 and describes a double-headed, oil-less 1/3 hp compressor, but publishes no current draw and no wattage (OxyHealth Fortius 420). Horsepower is not amperage. It cannot be converted into amperage honestly, because the efficiency, service factor and startup behaviour of that particular motor are not published either. So the correct entry in your load list is Not published — and the correct next step is to read the compressor's nameplate, or ask the seller to photograph it, before an electrician quotes anything.

Rigid chambers can be just as quiet on this point. The Sechrist H-series clearance publishes electrical figures only for the chamber's internal power supply — an input range of 90 to 264 VAC, +12 VDC nominal out at 3.3 A maximum, and a half-watt audio output inside the chamber (FDA 510(k) K140559). Those are internal supply figures. They are not a facility service requirement, and reading them as one is how people end up with an undersized circuit and a clean paper trail proving they never had the right number.

What we actually ask before quoting an install

Three things, in this order. What else is on that circuit — because a 20-amp circuit in a spare room is very often already carrying the room's receptacles. What the compressor's nameplate says, in a photograph. And whether the concentrator and the compressor are intended to run on the same circuit at the same time, which is the default assumption unless somebody has decided otherwise on purpose.

With a 6.0-amp concentrator against a 16-amp continuous ceiling, a single 20-amp circuit can look workable on paper and still be the wrong answer, because the compressor's real draw is unknown and the circuit is rarely empty. A dedicated circuit is a small line item during construction and an expensive one afterwards. If you are having any electrical work done anyway, this is the cheapest moment in the life of the installation to get it right.

Published circuit requirements for a range of chambers, and the difference between a circuit requirement and a measured load, are in Electrical requirements. What this line does to a budget is in The costs nobody quotes.