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25-08-2020, 12:41   #1
jamesd
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Home generator

Having been without power for 68hrs last week I have decided to get a generator.

I have ordered this:Pacini 7.5kva Silent Diesel Generator, Electric Start with AVR, link: https://ige.ie/pacini-7-5kva-silent-...oaAmLsEALw_wcB

I rang my local electrician last night and he will install a manual change over switch for me.

On it I would like to keep running:
1) Chest freezer
2) Fridge with freezer
3) Waterpump for solid fuel stove
4) Well pump
5) 700W UPS that runs my internet connection into the house and the router - no load on this UPS at all only a modem and a router
6) A few light bulbs - all led

Should I be well covered with the 7.5Kva ?

When powering it on should I be switching off the freezer and well pump then on one at a time ?
Plan would be in an outage to let it run during the day and then power it off at night and on again in the morning.

What would be the max length of cable / type of cable I should use to allow me to keep the generator away from the house a bit for noise ?

Lastly : Would you put this into some type of hut / cover when running to keep rain off it (with access for exhaust to vent ?)
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25-08-2020, 15:17   #2
Pete67
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You should be fine. 7.5kVA is approx 6kW when you allow for non-unity power factor so assume that you can't draw more than 6kW continuously. But that's actually quite a useful amount of power to have available.

If you add up all the loads you want to run and it comes to less than 6kW (6,000W) then no problem.

Fridge / freezer and chest freezer are likely to be less than 500W each
waterpump for stove - probably 300W max
Well pump - 2500W to 4500W depanding on the size of the motor - check the rating plate.
UPS with small loads - maybe 150W
LED lights - less than 10W each unless you are talking about outdoor flood lights.

Fridges and freezers do not run continuously either.

One thing to be aware of is high starting current of electric motors - for example a 2.5kW motor may draw 5kW for a few seconds while starting up. As long as all the motors do not start at the same time this is not usually a problem.

When changing over to generator during a power cut, don't just change over the manual switch with all loads on. Switch everything off first, start generator, change over the manual switch and then add loads one at a time. Your generator will thank you.

I've run my house lights (all LED), computers, fridge, TV, router etc and the gas fired central heating on a 2kW inverter generator during a power cut and most of the time the generator is just idling.

If you want the generator to work when needed then once a month start it and transfer some load for about 30 mins. Check oil level and top up as necessary. Keep the fuel tank full to avoid condensation inside the tank, and lastly consider a small solar panel to keep the starting battery fully charged.

The generator is air cooled so the most I would do is build a lean-to shelter open on three sides to keep rain off.

Last edited by Pete67; 25-08-2020 at 15:29.
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25-08-2020, 15:48   #3
jamesd
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Thank you very much, some good advise on powering all the main items off first then powering up the generator.

I will not be able to check the startup wattage on the well pump as its deep deep down but would I be able to check it with something like a clamp on amp meter on the cable where it is plugged in ?

Would an oil boiler be a heavy load to start/run - Ive been looking online and can see its 230V with a 5amp fuse but cannot get any more into on its startup or running.

For running a computer / TV - once the generator has the auto voltage regulator is that smooth enough to run them with out any issues ?
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25-08-2020, 16:03   #4
Pete67
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You can use a clamp on ammeter to measure the well pump starting / running current but you need to make sure that the clamp is around one or other of the live and neutral conductors - not both. That may be easy or not depending on how it is connected. Something like this might also be useful.

Running an oil boiler should also be no problem, if it has a 5A fuse it's likely less than one kW starting current, probably only a couple of hundred watts running load.

The output from a generator with an electronic AVR should be good enough for most electronics, most devices now have switch mode power supplies which are fairly robust anyway.
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25-08-2020, 16:34   #5
jamesd
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I have one of them ordered now, with the clamp on I was thinking I would build myself a short extension cable with the neutral wire exposed for clamping onto so that little plug in device is much easier to use.

Expecting delivery this week , will pop up a few pics once all is installed as might help others in the future.
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25-08-2020, 19:19   #6
2011
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What would be the max length of cable / type of cable I should use to allow me to keep the generator away from the house a bit for noise ?
A longer cable is possible but as the length increases the conductor size should also increase (to limit the volt drop).

7.5kVA = around 33 amps, therefore I would select a cable of at least 6mm sq. and for a run of 10m I would select at least a 10 mm sq.


Quote:
Would you put this into some type of hut / cover when running to keep rain off it (with access for exhaust to vent ?)
No, I would keep the generator in a shed and wheel it out and plug it into a generator outlet when as required. Otherwise it will be a rusty mess when you actually need it.

Personally I would avoid supplying expensive electronic equipment from a generator such as this. It may be ok, but personally I wouldn't risk it.
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26-08-2020, 10:42   #7
jamesd
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Thanks 2011 , so something like this would be a safe bet ?

https://www.justgenerators.co.uk/def...ion-cable.html

25m 32A 240V 2.5mm Extension Cable Details

Core Size - 2.5mm
Cable Length - 25m
Amps - 32
Voltage - 240V
Approved - BS4343

So once the cable is of the correct core size there is no issue with distance in it.

I could keep the Generator in my garage and bring out when needed, I am wondering through if its raining for a few days is that any harm to the generator ?
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26-08-2020, 12:13   #8
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A core size of 2.5 mm sq. is too small. You need a far larger cable for that or you will have excessive volt drop especially with larger currents and at 25m.

Also the plug and sockets are only rated for 32A. This is right on the edge as the generator can push out slightly more than this. I would go for 63A ratings.

Edit: I was wrong abut this ^^^. Going with a 32A plug / socket makes sense as this aligns with what is on the generator.

High level general explanation:

Longer cable run = larger cable size (normally)

For a given cable size as the length increases the resistance also increases. This is generally dealt with by increasing the cable conductor size.

Higher resistance for a given current through a given conductor = higher volt drop across the conductor.

Last edited by 2011; 26-08-2020 at 13:33.
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26-08-2020, 13:36   #9
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See correction made to above post ^^
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26-08-2020, 14:10   #10
jamesd
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Thank you again - So for a 25m cable I should go for 6mm sq. to reduce my voltage loss due to its length.
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26-08-2020, 16:30   #11
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Thank you again - So for a 25m cable I should go for 6mm sq. to reduce my voltage loss due to its length.
A calculation would have to be done to be sure.

An online calculator (don’t know how good it is) tells me that L+N resistance of a 25m cable with 6 mm sq. conductor is 0.1425 Ohms. At 30 amps this equates to a volt drop of 4.3 volts. This is a 1.9% volt drop before you even get to the board.

25m is very long! Would you not consider shorter ?
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26-08-2020, 16:51   #12
jamesd
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I would think I should be able to go a lot shorter, I think that 10 meters will do all I need to get it away from the house.

Generator should be arriving at the end of this week, I will more than likely then be praying for a power cut to test it.
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26-08-2020, 18:09   #13
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I will more than likely then be praying for a power cut to test it.
You don't need a power cut to test it!
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27-08-2020, 03:02   #14
Sir Liamalot
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No, I would keep the generator in a shed and wheel it out and plug it into a generator outlet when as required. Otherwise it will be a rusty mess when you actually need it.



I just use modern generators instead that don't burn things.

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02-09-2020, 15:08   #15
ozymandias10
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I just use modern generators instead that don't burn things.

where can you get this
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