Essay coming up!
That's a really good question about whether there's anywhere on the net where you can find those details, because while I know how my salary is compared with the industry average for my skills, experience and sector - I've no idea about on-call payments, what people would normally expect. So I hope someone else will know, because I'd be interested to know now.
Do you get paid £12 an hour for actual work done, or just for being on-call, so you'd get £144 for a 12 hour on-call shift, even if you didn't get called, or you'd get £24 because you only actually worked 2 hours? (And yes, you will have to pay tax, because it is earnings - that's down to HMRC rather than your employer.) How does it compare with your annual salary? £12 an hour works out at about £25000 before tax for a 40 hour week, so if that's what your salary is, then fine. If you're on more, then I'd expect to get at least my normal hourly week.
What counts as responding within 15 minutes? We have to respond, as in answer the phone within 15 minutes. We don't have to log on that quickly (indeed, I'm not sure my work laptop will log on that quickly currently, with all the monitoring software and so on it's got on it these days! But I do track my time from when I start to log in, not from when it actually gives me a useable screen.) If you're actually expected to log on within in that time, it basically means you're housebound for the on-call period, and IMO, that would deserve higher recompense, but that's just my opinion - I don't know if there are any rules governing on-call payments.
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When I worked at a previous place, I got a payment per on-call shift, which was 17:00-09:00, and at weekends & bank holidays, also 09:00-17:00 during the day. There was one rate for primary, and a lower rate for secondary (as there was less chance of being called out.) I can't remember what the rate was (it was a few years ago.) It was enough to be worth covering on-call for someone else if you were saving up, but not enough that you'd make a massive fortune - and there always were a few swaps needed because people have lives outside work.
Then we got £5 for every call, and then you got paid for any actual work, which was time and a half for weeknights and Saturdays, double time on Sundays, and triple on bank holidays.
The on-call rota went from Monday-Friday and then the weekend, and you'd get to do primary, then secondary, and we had about 10 on the rota, so you'd get a fairly good break in between. I was living in a shared house at the time, and they paid for a second phone line which was only accessible from my room, and paid all the bills - I never saw a bill for it (and also didn't use it for anything other than work.)
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Where I currently am, we have an annual pot of £10K between the UK team (we actually share on-call with other teams in Europe, but they get paid differently for some reason.) So currently there are 4 of us, so it's an extra £2500 a year; previously it was £2000 till X left (not replaced, as it was a redundancy.) But because we share the rota with a team in Europe, the rota is one week in 7 usually, which is fine.
On top of that basic payment (which, because it's not per shift means there's less incentive to cover for other people), you can claim overtime or TOIL for work actually spent working on calls that's over half an hour. I think it's single time unless it's a bank holiday, when it's time and a half. On-call is again from 17:00 - 09:00, though in reality, it's a bit variable, because we work over more than one timezone, and in any case, none of us works an exact 9-5, so during the week, there's usually someone in the office from around 7am to 7pm, and they'll probably have half an eye on the monitoring screen and the ticket queue.
We can also claim back broadband costs up to a certain amount, although they're talking about scrapping that, as they reasonably argue that these days, everyone would have broadband anyway, even if they didn't do on-call or work from home, and it's a fair point, so I won't be surprised when they finally say, no, you can't claim that any more.
We are meant to respond within 15 minutes of being called. If we don't respond, they have to call again, and if we don't respond a second time, they have to escalate to the on-call manager. You're meant to be able to log on within half an hour, I think - it means you can at least go into town or the supermarket, and I have been to parties with my laptop (and actually had to spend time online at one last Christmas.) If something's going on which isn't local, I'd arrange a swap.
It's not as good a deal as my previous place.
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Another thing to look at is the on-call burden (and I tend to ask about this at interviews, as it can have a massive effect on the quality of your life.) Hardware tends to be a lot more resilient these days, with more built-in redundancy, so servers are less likely to keel over because they accessed a dodgy memory block, plus we can usually have remote power consoles these days, so even a hard reboot doesn't need a site visit. It's probably about a decade since I had the sort of on-call week which meant I got more than one call every single night, and ended up at the end of the week jumping just because the microwave pinged, and I automatically checked my pager (it's just a mobile phone these days.) It's still possible to have a really bad night, but then it's usually a single bad call, and usually it will be only one call. It's possible to go a full week without a call these days, which never used to happen. But there's still no amount of money which can make up for being woken at 3am for a broken computer, IMO. Lower payments are more acceptable if there's less impact on your free time and quality of life.
The other thing I've had in both jobs where I've had on-call (I had one support job where they only had the seniors on-call - that wouldn't work so well as a policy for me now, mind you!) is that if you have a really bad night, there's some flexibility about coming in late the next day or working from home. It's more acceptable if you don't have to be in any meetings, obviously, but it is accepted that on-call can screw up your sleep (and that is why I was late to work last Thursday, because I fell back asleep after my alarm went off, because I'd been called out - wasn't too bad a week - 3 other calls besides that, and mostly in fairly human hours, though it did rather screw up my plans for Saturday morning.) Also, if you have a really tricky problem, then you can escalate, and the on-call manager can call round to see if someone else with the required skills is available to assist - there's a certain amount of goodwill relied on there, but to be fair, it only happens very rarely, so there is enough goodwill, but if it got more, there would be more comments about they should improve the documentation and send us on training for the knowledge gaps. There were also more of us called (when we weren't actually on-call) when the air con failed in a datacentre one summer. That was a bad weekend...