Blog · Selection Guide
Metered vs Switched vs Outlet-Metered PDU: How to Choose
Every PDU RFQ we answer starts in the same place: which grade of intelligence does this rack actually need? Buy too little and you fly blind; buy too much and you pay for relays nobody throws. This guide separates the three tiers by the problem each one solves, then settles it with a decision table, five filter questions and factory-direct price bands.
Vendor datasheets make the three tiers sound like points on one quality scale, as if an outlet-metered PDU were simply a "better" metered one. They are not. Metering, switching and outlet-level metering are three different capabilities that answer three different questions: how much is this rack drawing, can I recover a hung device without a site visit, and which device consumed this energy. Your answer to those questions — not a budget line — is what should pick the tier.
If you already know your input plug and phase requirements, our selection guides cover plug charts and single- vs three-phase sizing. This article picks up after that: the intelligence tier.
The three tiers, one paragraph each
A metered PDU measures at the input: per-phase voltage, current, kW, kWh, power factor and THD at ±1% accuracy, streamed over SNMP or REST into your DCIM. It tells you what the rack draws and how balanced your phases are — it touches nothing. This is the tier for capacity planning and PUE work; see our metered rack PDU for the full measurement set.
A switched PDU puts a relay behind every outlet. You can power-cycle a hung device remotely, sequence groups on with a programmable 0-999 second delay, and enforce an on/off policy per socket. The relays are the point: rated for 100,000 mechanical cycles because recovery-by-relay is a routine operation, not an emergency hack. It is the tier for unmanned sites; the switched rack PDU page shows the sequencing logic in detail.
An outlet-metered PDU measures at every socket — current at ±1% and energy at ±2% per outlet, with a 15-minute kWh freeze value that billing systems can read. It answers the attribution question: which tenant, which miner, which cabinet row consumed what, and when. That is the tier for colocation invoicing; the outlet-metered PDU page covers the billing data model.
The tiers overlap at the top: a switched unit on our line includes input metering, and a switched + outlet-metered combo carries both relay banks and per-socket billing data. What never overlaps is the upgrade path — there is none (see the FAQ below).
The decision table: who should buy which
Match your situation to a tier before you match it to a price. Each row carries the number that usually decides it.
| Your situation | Buy this tier | Why — the number that decides | Watch out for |
|---|---|---|---|
| Enterprise rack, capacity planning and PUE | Metered | ±1% input metering feeds DCIM; global average PUE has sat at 1.56 for five years because sub-rack loads stay invisible | No per-device attribution — fine for planning, not for charging |
| Colocation billing tenants per outlet group | Outlet-Metered | Per-outlet ±1% current / ±2% kWh with 15-min freeze values invoice without disputes | Insist the input metering is billing-grade too, or the rack total and outlet sums will drift apart |
| Edge or micro-DC site, unmanned | Switched | A truck roll runs $600-1,200; one avoided reboot visit pays the tier premium | If you also trend load, order switched + metered input |
| Mining or HPC racks, per-rig P&L | Outlet-Metered (or Switched + OM) | Electricity is 75-85% of mining opex and break-even sits near $0.07-0.08/kWh — per-outlet kWh is how you find the coasting rigs | High ambient temperature; check the unit's operating range |
| Broadcast studio or OB-truck racks | Switched | Sequenced startup (0-999s delays) prevents the inrush pile-up that trips upstream breakers | Leakage-current monitoring is a separate feature — ask for it |
| Lab or GxP-regulated environment | Outlet-Metered | Exportable interval logs are audit evidence; input-only totals do not survive an audit | Check log retention depth before you commit |
| Spare or budget rack, no telemetry need | Basic | Factory-direct FOB around $60-120 — spend the difference where it matters | No remote recovery, ever. A hung device means a person and a screwdriver |
Five questions that settle it
Run these in order. The first "yes" usually names your tier.
- Does anyone invoice against this rack's energy — tenants, cost centers, per-rig P&L?Outlet-Metered
- Can a person reach this rack within an hour when a device hangs?If no: Switched
- Will this rack's load data feed capacity planning or PUE reporting?Metered
- Do devices here need ordered startup to avoid inrush trips?Switched
- Is this rack a spare, a test bench or a short-lived deployment?Basic is honest
What the tiers cost, factory-direct
Buying direct from the manufacturer, typical FOB reference bands run: basic $60-120, metered $120-260, switched $200-450, outlet-metered $260-500, and switched + outlet-metered $400-700. Three variables move you inside a band: input amperage (16A to 63A, with three-phase WYE at the top of the range — a 63A three-phase unit delivers up to 36kW), outlet count (8 to 48 per unit), and whether you need locking sockets. If a quote lands far above those bands for a standard configuration, you are paying for a logo, not for copper. Our OEM/ODM program prices custom outlet mixes and branding against the same bands.
Two mistakes we see in RFQs every week
The first is overbuying switching: a team specs switched units "for control" on racks nobody will ever remote-reboot — staffed enterprise rows where the walk to the cabinet takes ninety seconds. Those racks needed clean ±1% visibility, and the relay premium bought nothing. The second is underbuying metering for colocation: an operator deploys input-only metered PDUs, then discovers mid-contract that two tenants share a rack and the input number cannot be split. Retrofitting per-outlet metering means a forklift of every PDU in the row. The FAQ below covers the borderline case.
One more footnote for North America bound orders: whichever tier you choose, verify the safety certificate is UL 62368-1 — the old UL 60950-1 was withdrawn on 2020-12-20 and a "60950-certified" new unit is a red flag. We explain the timeline in UL 62368-1 Explained, and the metering claims in What ±1% Billing-Grade Metering Actually Means.
Frequently asked questions
No. Per-outlet switching needs a relay behind every socket, a switching PCBA and a control processor — hardware that has to be designed in and tested at the factory. Decide the tier at purchase; a metered unit cannot be field-upgraded to switched.
On AmpRack switched PDUs, yes at the input: phase-level V, A, kW, kWh and power factor stream over SNMP alongside switching. What a plain switched unit does not give you is per-outlet kWh — that requires the outlet-metered grade, available on its own or combined as switched + outlet-metered.
If each rack houses exactly one tenant and the contract references the feed, ±1% input metering is defensible. The moment two tenants share a rack or a tenant adds equipment mid-month, input-only numbers become estimates. Shared racks need per-outlet kWh with interval freeze values to invoice without arguments.
Sources: Cloudatler, Edge AI / micro data center TCO handbook (truck roll cost basis, cloudatler.com) · Simple Mining, 2026 mining profitability analysis (electricity share of opex and break-even kWh price, simplemining.io) · Uptime Institute, Global Data Center Survey (PUE plateau, uptimeinstitute.com) · AmpRack factory-direct FOB reference bands, September 2026. Price bands are orientation values; request a formal quote for your configuration.
Still torn between two tiers?
Send us the rack's load list and who reads the data. An engineer will name the tier, the input and the outlet mix — and quote it FOB — within 48 hours.
