Akuvox EC33 Relay Outputs — What You Can Actually Switch
The relays on an EC33 board are marked 2A 30VDC / 0.5A 125VAC.
That is the rating of the relay component, not a spec for what you should switch with it. Akuvox
publishes three different answers for these outputs — and one of them is higher than the relay's own
marking. Here is what to actually design to.
- Design at 12 V DC nominal. Hard cap at 24 V DC / 2 A, resistive.
- Treat every EC33 output as a pilot contact, not a load contact.
- No NC terminal exists. The block is NO/COM only.
- Do not switch AC on these contacts.
- Anything above 12 V, anything inductive (strike, maglock), or any AC load goes through an interposing relay.
What Akuvox Actually Publishes
There is no single official figure. These three sources disagree with each other:
| Source | Stated rating | Use it? |
|---|---|---|
| Knowledge base — Relay Output of Indoor Monitors, resistive-load table, EC33 row | 30V 3A |
Noexceeds the part 3 A is 50% above the 2A printed on the relay itself. |
| EC33 Lift Control Administrator Guide — Model Specification table | Relay (24V2A 0.21W) × 32 |
Yesdesign to this Lowest published figure, and it sits inside the relay's own marking. |
| EC33 datasheet & akuvox.com product page | none given — only “Relay Output: 32” | — |
There Is No NC Contact
NO and COM only — three relays per block
The EC33 relay connector is NO1 / COM1, NO2 / COM2,
NO3 / COM3. There is no normally-closed pin anywhere on it.
That means any fail-safe application — a maglock, or anything powered-to-lock — needs an interposing relay regardless of voltage, because you need an NC contact the EC33 cannot give you.
Verified against the EC33 Quick Guide wiring diagram (TZ-SM-002809 V1.3), where the relay is shown wired in series with the elevator button authorization line.
Do Not Switch AC
Akuvox publishes no AC rating at all for the EC33 — both of its figures are
unqualified and read as DC. The relay component's own AC rating is 0.5A 125VAC, which is a
quarter of its DC current allowance.
Anyone applying “30V 3A” to a 24 VAC strike is running roughly six times over what the contact is marked for on AC. Use an interposing relay for any AC load.
About the “16 V Maximum” You May Hear
Some experienced installers hold EC33 relays to about 16 V DC. We checked, and no Akuvox document states that figure — not the knowledge base, not either version of the admin guide, not the datasheet, not the quick guides, not the product page. We are not publishing it as a manufacturer specification.
It is, however, a sound field rule, and worth understanding: 16 V is the natural headroom ceiling of a 12 V system (13.8 V battery float, 14.4 V boost, ripple peaks near 15 V). Keeping a DC load at 12 V nominal also holds it at or below the roughly 12–15 V arc-ignition threshold of these gold-flashed silver-nickel signal contacts. DC has no zero crossing to quench an arc, so a 24 V circuit arcs on every release while a 12 V one largely does not. Read “16 V max” as shorthand for 12 V hardware only — don't put 24 V on it, rather than as a limit the board enforces.
Use an Interposing Relay
Drive the coil, not the lock
Wire the EC33 NO/COM pair to the coil of an external relay.
A coil is a small, constant, easily suppressed load well inside the contact rating.
Power the lock separately
Run the strike or maglock from its own fused, battery-backed supply, switched by the interposing relay's contacts. This also keeps any fire-alarm break in the lock power path independent of the controller.
Put the suppressor at the load
Fit the reverse-biased diode across a DC lock coil, or an MOV on AC hardware, at the lock — not back at the EC33. Suppressing at the far end of the cable does not protect the contact from the inductive kick.
Pick NO or NC at the interposing relay
Since the EC33 has no NC contact, the interposing relay is where you choose fail-safe or fail-secure.
Why We Err Low
The EC33's relays are soldered to the 32-output main board. If a contact welds you are replacing the whole controller, not a relay — and on an elevator a welded contact means a floor that is permanently authorized or permanently locked out.
An interposing relay moves that wear into a socketed part you can swap in minutes. A relay you did not strictly need is a far better outcome than a controller you did.
Quick reference — what needs an interposing relay?
Yes: anything above 12 V DC nominal; any electric strike or maglock; any inductive load; any AC load; any fail-safe (powered-to-lock) application; any lock on its own supply.
Direct from the EC33 contact is acceptable only for: a dry pilot signal — an elevator button authorization line or similar — at 12 V DC nominal, well under 1 A including inrush, with suppression at the load.
Figures cross-checked against the Akuvox knowledge base resistive-load table, both versions of the EC33 Lift Control Administrator Guide, the EC33 datasheet and product page, and the EC33 Quick Guide (TZ-SM-002809 V1.3). Relay component marking read from the board itself. Where sources disagree we publish the lowest figure.