Author Topic: More generator questions  (Read 4503 times)

guest23837

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More generator questions
« on: October 22, 2018, 09:31:06 AM »
Can anyone explain (in simple terms) what a bridging wire in the generator earth is and how to do it. I'd also like to find out the output of the alternator there is no labels or plates on it. I only have a multimeter. Thanks

mike90045

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Re: More generator questions
« Reply #1 on: October 22, 2018, 04:54:41 PM »
I can't tell you.   There are many variables. How is the load wiring set up?  Does the generator have a Earthing Bolt ? What does electrical code in your city specify ?  Is there an existing Earthing Rod connected to a electrical panel?

So many things, it's not simple. You don't want a hazard and you don't want a ground loop.

BruceM

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Re: More generator questions
« Reply #2 on: October 22, 2018, 05:23:55 PM »
If the generator is to be powering circuits through the main circuit panel, the earth/safety ground connection should be there, at the panel, and connecting to the generator chassis. So your generator hookup would need a ground, a neutral and one or two hots. (Two if split phase).

Generally electrical codes try to avoid multipoint grounding and the ground loops that result.  Pity the same sound approach doesn't apply to the power co.

The safety issues of a transfer switch or other should be studied and considered. 

guest23837

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Re: More generator questions
« Reply #3 on: October 22, 2018, 05:32:29 PM »
I was reading somewhere that there should be a jumper cable between neutral and earth in the plug going into the generator if its connected to the house.

BruceM

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Re: More generator questions
« Reply #4 on: October 22, 2018, 06:11:16 PM »
It is preferred/best to have the Neutral to Safety Ground (earth) connection done at only one point- at the main meter panel.   If you connect to a sub panel this becomes more clear- the sub has neutral and safety ground busses separate - so that there is only a single point connection of neutral to earth at the main meter panel.   

Normally the neutral is low enough voltage to not kill anyone, so people get sloppy about neutral to safety ground shorts and the average home usually has a few...which do often cause elevated ELF magnetic fields.  But done properly, the safety ground should never carry current unless clearing a fault (tripping breaker).  The rules of the electrical code attempt to provide this but there is a great deal of misunderstanding and sloppy work out there.


guest23837

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Re: More generator questions
« Reply #5 on: October 22, 2018, 08:31:48 PM »
It is preferred/best to have the Neutral to Safety Ground (earth) connection done at only one point- at the main meter panel.   If you connect to a sub panel this becomes more clear- the sub has neutral and safety ground busses separate - so that there is only a single point connection of neutral to earth at the main meter panel.   

Normally the neutral is low enough voltage to not kill anyone, so people get sloppy about neutral to safety ground shorts and the average home usually has a few...which do often cause elevated ELF magnetic fields.  But done properly, the safety ground should never carry current unless clearing a fault (tripping breaker).  The rules of the electrical code attempt to provide this but there is a great deal of misunderstanding and sloppy work out there.

And in simple terms? I really want to connect it to the house rather than running an extension cable through a window. If it's safe I'd leave it. BTW it's 230v system

BruceM

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Re: More generator questions
« Reply #6 on: October 22, 2018, 11:25:32 PM »
Connect the neutral to your generator neutral, the panel ground to your chassis ground.

Do you have just a single phase 230V and neutral or two hot legs with 460V between them (aka split phase)? Just interested in power configurations around the world.

How are you switching between grid and generator supply for your generator backup circuits?
How sophisticated you get might depend on whether the wife might need to use it alone.
I think idiot-proofing and best safety are wise choices. 




guest23837

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Re: More generator questions
« Reply #7 on: October 22, 2018, 11:43:16 PM »
My connection to the house was wired by a retired electrician. In Ireland domestic power is 230 volt single phase and he was backfeeding power into the house until the generator started putting voltage between neutral and earth. I got another alternator its different brushless type and I don't want to connect it to the house if it's going to kill someone. It's going to cost me the best part of a grand to get a changeover switch and wiring installed and certified by a spark. I really only understand the engine side of power generation so legs and phases are beyond me. I would like that the wife could throw the changeover switch walk to the shed and press the starter on the generator. She had a few goes but she wouldn't remember to turn off the power at the meter so thats out of the question.

guest23837

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Re: More generator questions
« Reply #8 on: October 23, 2018, 01:12:20 AM »
Glort it would probably never pay for itself as it would only be used during occasional power cuts. We wouldn't have more than 48 hours without power in a year unless there was a bad storm. I just like the idea of having power whilst my neighbours are sitting cold in the dark!
There's not enough sunlight here to justify fitting solar panels and in all honesty I could probably manage ok with a car alternator and an inverter a setup we talked about some time ago I could finish fixing up the LR1.

I have 4 steel rods each 3 feet in the ground and about a yard apart, I was thinking I could use this as an earth from the generator? The backfeed option is still available and we are a middle aged couple family all grown we tend to be at home or away together especially in the evenings/night.


dieselspanner

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Re: More generator questions
« Reply #9 on: October 23, 2018, 07:14:29 AM »
+1 for Bruce's point ref the wife!

A guy I met when I had a Dutch Barge added an inverter, on his boat, with strict instruction to his wife that only himself was allowed to plug into the shore (mains) power as it would be possible to backfeed the inverter was it not disconnected before hand.

After a couple of months with no problems they pull alongside and he announces he'll make a cup of tea. knowing he would fill the electric kettle and the swap out the inverter the Missus gave him a minute then plugged in the shore power cable.

Unfortunately he'd gone for a leak first.

The bang when the mains power blew the inverter was enough to soil his underwear apparently. the good news was that the toilet was at the other end of the boat from the said inverter.

I did as Glort suggested and fitted a second circuit for the inverter fed sockets, OK. it means pulling the plug out of the socket and putting it back in the mains fed one but it completely removes the possibility of a cock up of expensive, if not dangerous proportions.

Cheers
Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

guest23837

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Re: More generator questions
« Reply #10 on: October 23, 2018, 08:55:02 AM »
Thanks guys I will earth the generator to the rods and call it done! Small high speed diesel was very cheap, even with the replacement alternator and I want to use the power it makes. If I'm going to be in charge of the main breaker switch then backfeeding should be safe enough? It's close to the house and kinda noisy with the window open but that's not a bad compromise. I might try to modify the air intake to quieten it down I need to get some information on doing it and again it has to be cheap. Glort if I remove the standard air filter and extend the pipe to the intake is that how it's done?

guest23837

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Re: More generator questions
« Reply #11 on: October 23, 2018, 10:19:48 AM »
So Glort do you think if the generator is earthed it's safe enough to connect to the house? I have some flexible pipes i can try on the air intake when I get the chance thanks for help and advice!

guest23837

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Re: More generator questions
« Reply #12 on: October 24, 2018, 10:52:56 AM »
I connected an electric kettle 2.2 kw hairdryer 1.6 kw voltage dropped to 217 volts and frequency to 49.8 thats way more than I will need so happiness abounds in the shed! I had a minor panic attack when the oil pressure light came on, turned out it was the switch I applied 60 psi and it stayed lit! I assume any low psi switch with the same thread will do.

guest23837

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Re: More generator questions
« Reply #13 on: October 24, 2018, 03:54:25 PM »
Sorry Glort FFS also means fat finger syndrome it was 217v

guest23837

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Re: More generator questions
« Reply #14 on: October 25, 2018, 09:59:52 PM »

You could try it that way Paul. If you used the standard air box, I would try to have it on a flange to a much larger diameter pipe that will act like a Plenum and reduce the gas speed which will help quiet the intake noise.  You can also add a new muffler to the intake and stick the air box on the end of that.
Myself, I'd be looking for a larger car intake from a wreckers. They have a large airbox, a filter size you will never need to replace and often a lot of baffling to cut the noise down. Going oversize will always make a significant reduction in racket.

Is the machine housed in a shed?  If so, you could look at Building a box around the thing with a baffled intake and output for the cooling air and possibly direct the intake and exhaust to the far side of the building from the house. If you enclose the machine it a good idea to bring cold air in from outside the enclosure otherwise you are basically generating a heat loop by sucking hot air in and through the machine which will make it run hotter.

If it has electric start, you could also get a radio switch off fleabay and wire the thing up so you ( or the mrs) could just press a button and off the thing would go.

There isnt much room to attach anything to Glort, I have attached a photo of a yanmar air filter housing. If I remove the stock filter I could extend from the round inlet? I have a length of hose it was used to connect to a vacuum for woodworking tools but its serrated, would it make any difference?