@domlouis
I am no electrician but I looked into all this a while back. In short, you should be absolutely fine, below is a rehash of an old post I did.
Power (watts) = Voltage (volts) x Current (amps)
A 32a ring main circuit is designed to take about 7,700 watts, Looking at a 5a fuse in a game implies that you can only put 6 on the ring main before maxing it out. This is a completely false conclusion. I have had 13 running on mine for example.
My pinballs all use much less than 5a each. It depends on the game, incandescent v led lights, any big motors in them etc, but my pinballs use about a THIRD of this 5a rating.
When electricians do load calculations they have to make assumptions about how many things you will have on at once, what power surge they will create when you switch them on, what average consumption they expect during actual use etc etc etc.
The main fuses on your games have to cope with real world conditions including the nanosecond surge in induced current when you power the game up, and the fact that consumer fuses are supplied at standardised currents (1a, 5a, 13a etc)
One thing to discuss with your electrician is what type of breaker you use at the feed end (next to your existing fuse board, that will protect your new long cable from rodent attack, you driving a nail into it etc) and in your new games room fuse board. There are 4 different ratings for the sensitivity of breakers, these determine the "induction surges" they can cope with, and how quickly they trip (fractions of a second). If a breaker ever trips it would be better for you if the one in the games room is more sensitive (therefore trips first) than the one next to your fuse board so that you do not have to reset both of them every time.
I bought one of these to check it out for around £10, the price seems higher now ....
http://cpc.farnell.com/energenie/ener007/power-meter/dp/PL13026?mckv=sJXnoAIac_dt|pcrid|189414267096|kword|ener007|match|p|plid|&CMP=KNC-GUK-CPC-SKU-Home_Automation_/_Smart_Home_|_PL13026
View attachment 44637
It gives power consumption to within 0.1 of a watt. Including minimum, current and peak power. It claims to be accurate within +or- 2%
I had my shadow (all led) and stern world poker tour (all led, with crappy fluorescent backbox light) BOTH plugged into it via a surge protected quad adaptor socket.
With these games BOTH on, my playing one then the other for a while it said that
Peak power consumption was 767.1 watts which is about 3.2 amps (versus the 2x5a fuses or 10a the games run on)
Minimum power consumption 167.2 watts
Both games in attract mode consume in aggregate about 230 watts
Plugging into paragon alone, which has all incandescent lighting
Peak power consumption was 409 w which is about 1.7 amps (versus the 5a fuse the game runs on)
Minimum power consumption was 180 w
In attract mode, power consumption was about 230 w
To "check" the accuracy of the power meter I tried it on a fan heater that is marked 3000 watts. This device read 3219 watts peak power consumption which sounds about right
I know that this thing is bound to have limitations, but it gives something of a real world flavour