What to check before signing a UPS AMC
Two contracts on the same machine can differ by three times in price and by rather more than that in what you actually receive. The difference is almost never on the front page.
An annual maintenance contract sells you a number of visits, a response commitment and some position on who pays for parts. All three are negotiable and all three are written loosely as standard. What follows is what we would read first if we were buying rather than selling.
The visit is the product
A preventive visit that consists of looking at the display, wiping the filter and signing the log book has cost you a morning of somebody’s time and told you nothing. Ask what is actually performed, and ask for it in the contract rather than over the phone.
- Input and output voltage and current on every phase, recorded — not glanced at
- Load percentage against the machine’s rating, so you can see the trend across visits
- DC bus voltage and individual cell or block voltages across the bank
- Battery terminal torque and a look for creep, corrosion and swelling
- Ambient temperature at the bank, not at the door
- Fan condition and filter state, with the hours run since last change
- Alarm and event log downloaded and read, not cleared
- A written report you keep, with the readings on it
The readings matter more than the visit. One set of numbers is a snapshot. Four sets across a year is the only way anyone spots a bank drifting, a fan slowing or a load that has quietly grown past what the machine was sized for.
The clause most contracts leave out
Ask whether the contract includes a battery discharge test under load, and how often. This is the single clause that separates a real contract from a paper one, and it is usually absent.
The reason it matters: a battery sitting on float charge reads close to its nominal voltage almost until the day it fails. A multimeter across a healthy bank and a bank with a third of its capacity left will show you roughly the same number. Voltage tells you the charger is working. It does not tell you the bank will hold the load, and holding the load is the only thing the bank is for.
A discharge test puts a real load on the bank and measures how long it actually sustains it. That figure — not the voltage, not the age, not the manufacturer’s rating — is your backup time. Sites discover the gap during an outage otherwise, which is the most expensive possible moment.
The clause to insist on
One load-bank discharge test per contract year, with the measured runtime written into the report. If the vendor will not commit to it, ask why — the answer is usually that they do not own a load bank.
Comprehensive or non-comprehensive
The distinction is about who pays for parts, and the gap between the two prices is roughly the vendor’s estimate of what your machine is going to cost them. That estimate is worth knowing.
| Non-comprehensive | Comprehensive | |
|---|---|---|
| Preventive visits | Included | Included |
| Breakdown attendance | Included | Included |
| Labour on repairs | Included | Included |
| Consumables — fans, filters | Usually chargeable | Usually included |
| Boards and power modules | Chargeable at cost | Included, subject to exclusions |
| Batteries | Chargeable | Almost always excluded — read this line |
| Price | Lower | Meaningfully higher |
Batteries are the line to read twice. They are the largest recurring cost in the life of a UPS and they are excluded from most comprehensive contracts, which makes the word "comprehensive" do more work than it should. If batteries are genuinely included, the contract will say so explicitly and the price will reflect it.
Response time, and when the clock starts
A four-hour response time means nothing until you know four hours from what. From the call being logged, or from the engineer being assigned? Within business hours, or around the clock? And what happens at hour five — is there an escalation path with a name and a number on it, or does the commitment simply lapse?
Also worth settling before you sign: whether a load-down call outranks a scheduled preventive visit elsewhere. It should. If the contract does not say so, you are competing with the vendor’s calendar at the moment you can least afford to.
Spares, and the machine you actually own
For an older machine, the honest question is whether boards are still obtainable at all. A contract on equipment whose control board went out of production six years ago is a promise of labour, not of repair. Ask directly: if the inverter board fails in month seven, what happens? A vendor who says "we would have to look" is being straight with you. One who says "no problem" without knowing the model may not be.
Questions worth asking before you sign
- How many preventive visits, and what is performed at each?
- Is a battery discharge test included, and how often?
- Do I get the readings in writing after every visit?
- When does the response clock start, and does it run outside business hours?
- Which parts are excluded — specifically, not by category?
- Are batteries covered? If not, what is the replacement process and lead time?
- Is the engineer trained on this make and model, or on UPS in general?
- What is the escalation path when the response time is missed?
None of this requires you to know anything about power electronics. It requires the vendor to be specific, and a vendor who will be specific in writing before the contract starts is usually the same one who turns up in month nine.
Questions we get asked
Anything not covered here, call us — most of it is faster to answer on the phone.
Is a comprehensive UPS AMC worth the extra cost?
It depends almost entirely on the age of the machine. On equipment inside its first few years, failures are rare and non-comprehensive is usually the better value. Past roughly seven or eight years, board failures become likely enough that comprehensive starts to pay — provided you have read which parts are actually excluded.
How often should UPS batteries be load tested?
Once a year is the sensible minimum for a bank you depend on, and twice a year once the bank is past the halfway point of its expected life. A voltage reading is not a substitute — a failing bank on float charge reads almost normal right up until it does not hold.
Can you take an AMC on a UPS made by someone else?
Yes. Most of what we maintain was built by somebody else. What matters is whether spares for that model are still obtainable, which we will tell you honestly before quoting rather than after.
What happens if the AMC response time is missed?
That depends on what your contract says, which is exactly why it is worth checking before signing. A contract with a stated response time and no stated consequence is a stated intention.