Generator Install

[danrich123]

I was asked today about installing a generator for a portakabin. I told him honestly that i know naff all all about generators etc. but would try to find out.
He wants the generator to power a portakabin on saturdays, just a few lights and small heater. The portakabin is other side of a field nowhere near a building.
How would installing a generator work for a portakabin. The units prewired with a RCD/CU and rotary isolator on the outside for the incoming supply. Could you wire up a 16A plug to the isolator and just plug this in to a generator.
Is it notifiable? i presume not?
Do generators need to be kept covered up? earthed?

cheers

 

[flameport]

Could you wire up a 16A plug to the isolator and just plug this in to a generator.
Is it notifiable? i presume not?
Do generators need to be kept covered up? earthed?

16A plug - depends on the maximum load of the cabin
covering up - depends on the generator
earthing - yes.

 

[big-all]

you had better ask him if he wants to boil a kettle as most people dont realise that kettles use around 3kw or 13 amps

 

[danrich123]

how would you earth the generator? stick an electrode in ground and attach to chassis?

If for example, someone tried boiling a kettle using 2kw gen, would the kettle simply not work, or would it just take longer to boil?

 

[big-all]

it would trip the overload or stall the engine if you peg it down

 

[big-all]

you could always buy a 1.5kw kettlehttp://www.amazon.co.uk/Domestic-Appliances-Breville-Kettle-Cordless/dp/B002TVCX44

 

[ricicle]

Usually on smaller generators you have to watch the configuration of the windings. For gennys supplying installations rather than one single piece of kit the Neutral should be bonded to the generator frame and then the frame earthed via a rod.
30mA RCD protection is almost always required for smaller gennys and temporary installs.

 

[big-all]

or 1kw
http://www.jacksonscamping.com/?pc=/product/3405/

 

[ericmark]

1) Be very careful on earthing. Not all generators have the earth connected to one leg and both centre tap and 55 volt taps are possible which can only really be used with class II equipment.

Most generators have built in RCD but often it is of the variable type and care is needed to comply with regulations as to who can alter the settings.

Earth rod is not so easy either as it needs covering so no one can get too close normal is to put generator on top of earth rod or cabin on top of earth rod then on one can get too close.

YY cable was common feed method often with plug and socket arrangement but small generators are not very reliable and often need changing and I have had problems where larger replacement has had 63A MCB and you need to ensure all paperwork is available so if changed there is no excuse for not testing.

We hired generators and because of reliably we ended up with nothing smaller than 7.5Kva not that we needed that size they only charged radios and worked aircraft nav lights when the big generators 750Kva where not running over night.

Falklands we had a load of Lister 3.5Kva units revving at 1500rpm which we did a lot of work on but were more reliable than the other smaller diesels revving at 3000rpm with 5Kva output.

There are now some specials that tick over until loaded and these come in two different types. The first gives around 15Hz at 30vac until loaded then revs up to give 230vac at 50Hz you need to be careful with these as small loads like florescent lamps often will not cause them to rev.

The second type uses a built in inverter and delivers 230vac at 50Hz what ever speed the engine is doing. A lot better but often not true sine wave and some equipment may not like running off them.

The older types have many different ways to control voltage the series / parallel field winding is quite popular and these have two resistors the parallel winding sets open circuit voltage and the series winding the on load voltage but the voltage can vary from 200 to 250 according to load and one has to be careful that equipment can work on that range. That type often by design will cause field to collapse when overloaded and not much good to run motors. The electronic AVR does give a much more stable voltage.

Other than inverter type droop can be a problem (revs dropped no load to full load) and we tended to set the revs slightly high at say 55Hz at no load so still had 45Hz at full load again check what they are using.

Noise was also a problem and if you need to worry about noise the again look at inverter models so they only tick over when on light load.

Also look at no volt start I have had it where generator has failed and the fitter has repaired with no access to cabin and left it running. And there has been an earn in the cabin which has then boiled dry. So we fitted active RCD's so power in cabin can't be turned on unless they have access to cabin. Although these can be a pain where the cheaper rev up under load generators are used often left a halogen lamp on to ensure always loaded.

People tend to fiddle so do inspect and test so if they do you have proof it was OK when you left it.

As to being covered up we never did they were designed to be run outside. However you may need some hefty chain I worked on traffic lights and you would not believe how often generators were stolen even when running traffic lights.

 

[Steve]

However you may need some hefty chain I worked on traffic lights and you would not believe how often generators were stolen even when running traffic lights.

Never mind gennys, they nicked both signal heads from a set of temp traffic lights near here the other night.

 

[JohnD]

it is not efficient or sensible to run a petrol generator to power heating and cooking or kettles. You are using expensive petrol to generate expensive heat then very expensive electricity to turn back into even more expensive heat. Get a gas heater/stove. Then the lighting load alone needs electricity, so you have more and cheaper options (including caravan fluorescents off a battery), or a gas lamp, or a pressure lamp.