Generator Hire Costs

Question

Not really a technical question, I got asked today how much would it cost to hire a generator short term (less than a week) 
 It would be for a restaurant 3-phase supply (100A x3), when they are going full tilt a couple of the phases are very close to 100A. 
 Its not going to happen but just wondered if anybody has experience and wondered what likely costs are.

mapj1 · Accepted Answer

Hire for very short terms is mostly delivery costs. Hire for very long periods is mostly dominated by fuel costs. The cost of machine is not a linear function of power rating, but fuel consumption is more or less proportional to engine size.. 
 So how much do you need - a load of 100A phase suggests a machine of plate rating 80-100KVA, but that is if (and only if) the load comes on slowly. If the load is very sudden - perhaps a single large oven, then a the genset needs to be oversized, a load jump of 25-35% of full load is about the most you can switch onto an unloaded machine in one hit without stalling. 
 Expect to fork out &pound;500 - &pound;1000 per week for the sort of thing that will do 100A phase, more for a nicely boxed one with built in fuel tank, like you may see at a pop festival, less for a noisy open frame type like you may use on a building site, and then there is the question of fuel tanks integrated or external, and that price range will probably not include the cost of getting it there, and delivery may involve a low loader or HIAB or if you can handle less power below 50KVA or so more like a horse box sized towable thing. That choice may also depend on accessibility of the site and how far it has to travel. If you need it for several weeks, like all hired items the price drops smartly. If you need it for years, buy it or lease it as a service. 
 If gensets do need to be paralleled with each other or with the incoming mains, that can be certainly done, but it is 'extra' in terms of the equipment complexity as the engine control panel and main contactor and interlocks need to be set up for this. And then we worry about earths and NE bonds, as on switch over you cannot rely on the DNO provided NE bond, but when in parallel you should not have two, at least in the UK where ECSQR applies. The rest of the world are more liberal about it ,and DNOs when they add generators during repairs do all sorts of odd things. 
 In any case you need DNO permission to add anything that has the potential to force current backwards up the street. (except small solar panels and a few other named things where they cannot refuse but just get notified.) 
 Mike.

Generator Hire Costs

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