Basic, metered, monitored, switched, transfer switch. The words on a PDU spec sheet describe two separate abilities: whether it can measure power, and whether it can control power. Everything else follows from that.
Basic: distribution only
A basic PDU splits one circuit into outlets. No display, no network port, nothing to configure and nothing to fail. It's the cheapest option and the right one for a closet you're in regularly anyway, or where the load is well understood and stable.
The limitation shows up the day someone asks whether another switch can go in that rack, and the honest answer is to put a clamp meter on it and find out.
Metered: you can see the load
A metered PDU shows current draw on a small display, usually in amps. That single number answers the capacity question on the spot, and it's the difference between planning an install and hoping.
Two flavors matter:
- Metered at the unit: total load for the whole strip. Enough for most rooms.
- Metered by outlet: draw per outlet. Useful when you bill customers for power, or when you're hunting the device that spikes at 3 AM.
Worth it when a rack is filling up, when you're adding PoE switches whose draw changes with the devices connected, or any time tripping a breaker would take down more than one customer.
In our range, the APC AP8830 (0U vertical, 120V 20A, twenty-four 5-20R outlets) and the APC AP7802B (2U, 120V 30A, sixteen 5-20R outlets) are metered units.
Monitored: the meter reports over the network
A monitored PDU is a metered one with an Ethernet port, reporting over the network so you can read the load without standing in the room. Most will alert you when draw crosses a threshold, which turns a breaker trip into an email you got two weeks earlier.
Switched: you can control each outlet
A switched PDU turns each outlet on, off, or off and on again, from a browser or an API. Nearly all of them meter as well, so switching is a superset rather than an alternative.
What it's really for:
- Remote reboots. A hung access point, camera or modem at a site 40 minutes away stops being a drive.
- Ordered startup. Power-on delays bring a rack back in sequence after an outage, so the firewall is up before the things that depend on it.
- Locking out an outlet. Keep a spare outlet dead until it's meant to be used.
The arithmetic is simple. If a switched PDU costs a few hundred dollars more than a basic one, and a site visit costs you an afternoon, it pays for itself quickly anywhere you don't work daily.
For a small closet, the APC AP7900B and the CyberPower PDU41001 are 1U, 120V 15A switched units with eight 5-15R outlets. For a 208V server rack, the APC AP8641 is a 0U switched strip with 21 C13 and 3 C19 outlets on an L6-30P plug.
Transfer switch: two feeds, one rack
An automatic transfer switch PDU takes two power cords, runs on the primary, and switches to the secondary within milliseconds when the primary fails. It exists because most equipment has a single power supply, and redundancy needs two sources.
Typical uses: feeding a rack from two separate breakers, or from a UPS and a wall circuit, so maintenance on the UPS doesn't take the rack down. Many transfer switch models also switch and meter per outlet. We don't have one listed right now, so email us for a quote.
Choosing quickly
| Your situation | Pick |
|---|---|
| Small closet, stable load, you're on site often | Basic |
| Rack filling up, more gear planned | Metered |
| Remote sites, gear that locks up, after-hours calls | Switched |
| Single-cord equipment that can't go down | Transfer switch (ask us) |
One practical note
Networked PDUs need an IP address, a firmware policy and a sensible place on the network. Put them on the management VLAN, not the guest network, and keep their firmware current like any other connected device.
Not sure which way to go on a specific site? Email support@rackit.com with how often you visit and what's in the rack, and we'll give you a straight answer. Browse all rack PDUs.