# Voltage to Earth



## Rich83 (May 17, 2021)

Hi, looking for some advice. Ive been fixing up an old Newton Derby 15kva 12wire single phase generator. Driven by a perkins 4108 so its def a good 40 or more years old. 
Replaced avr with new one, still didnt work properly, found 2 diodes detached, re solderd and holds 240v perfectly now 😄. 
My concern is that im gettin 110v neutral to earth and 80v phase to earth! Am i right to be alarmed about this? 
Can i/ should i tie neutral down to earth? My thought was to try it with a very low amp fuse? 
Thanks. Rich


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## iowagold (Jan 22, 2020)

first things first..
you could still have an issue on the gen set..
like a bad capacitor... or it could have a bleed down resistor to the chassis..
use an 100 watt incandescent light bulb to see if you have hard voltage

so how are you using the gen set?
as a construction gen set ??
or as a home back up power?

if you are as a construction gen set.
use a proper ground stake to the chassis ground.
and use a bonding plug from the neutral to the chassis.

now on home back up power
your gen set will get the neutral bond from the main service panel in the house.
as well as the chassis or earth ground if the house panel has proper grounding.


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## Rich83 (May 17, 2021)

Hi thanks for getting back to me Paul. Yes i do plan to connect up to the house as a back up but not until im sure everything is ok. I have bonded the chassis and an earth stake and wiring to the house will definately be up to spec when i get some cable. 
Yes i will definately put a lamp across ans see if it lights as you say that is a good start.
So do you think there is something wrong or could it be that the neutral actually required bonding down? N and E were not bonded when i got it but it did not come with a panel of any description so im thinking could it have been bonded further out. 
I have only powered up a 500w flood light which works fine, volts are steady L to N and L/N to E are still as i said before, i hoped with load on it would change. 
If im getting true volts from tbe neutral and i bond it down is it likely to cause damage.
Im not sure but thinking logically being single phase could the gen just chuck out almost even volts across L and N unless one was grounded?


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## iowagold (Jan 22, 2020)

yea with out it here it is hard to test..
the light for a load is a good test.
then see if the voltage drops when loaded.
that will let you know if it is phantom inductance...
or if it is a hard short to the frame.

it can have a stator slot in the windings that is hot flashed over to the frame...
that comes from over loading of the gen sets...
or lightning damage.
or a chaffed wire some where...

the pig tail test light works the best for sniffing out issues along with a volt meter connected to the same spot!
100 watt incandescent is what we use here... that is perfect for loading a hard short! and rated for the voltage in question...
so if the gen is a 240 vac gen use a 240 vac test light.
and if it is rated at 125 vac use a 125 vac test light.


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## Rich83 (May 17, 2021)

As soon as i get chance i will try it, hopefully tonight. Im intrigued now. Thanks.


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## Browse Deweb (Jan 16, 2021)

I always thought generators tied to a house should use the house's grounding.


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## Old man here (Nov 5, 2020)

Browse Deweb said:


> I always thought generators tied to a house should use the house's grounding.


Yes.


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## Rich83 (May 17, 2021)

Ok this is interesting to me, put a bulb as instructed across L -E and then N -E no light at all, not even a dim glow. L- N full brightness as expected. Just to check the bulb i put it across a 36v battery and as expected got a dim glow so the bulb is fine as far as i can tell. It was 42w, all i had! This was with a pin in the ground and i did not try it with the pin removed from ground but i dont think that would make a difference. What does this mean? If i stood bare feet on the ground and touched the L i would not get a shock? Would my rcd trip if there was a fault to Earth? Without sounding like a complete idiot how can it generate ac current if it doesnt produce current to ground?? I have way too many questions. Is it just the way a low zig zag works (which by process of elimination purely is what i think ive got). Where do i go from here, i need to test more generators and read up i think!!


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## Rich83 (May 17, 2021)

Is there any point to an earth on a gen set apart from protection of the chassis. Whats the point in connecting to house earth? I guess a L and N fault to bonded metalwork apart from that i cant see that it would operate any protection. Better to be safe than sorry obviously but im just trying to get my head around generators sorry for the lack of knowledge i will start reading up!!


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## Rich83 (May 17, 2021)

My not so full understanding leads me to believe that i could ground the L or the N, the other would come back live and it would then operate similar to our mains supply. I feel like non bonded generators are actually safer than the mains? Obviously this is all speculation and im here to learn not give myself a shock!!


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## tabora (Sep 6, 2018)

I almost hesitate to mention this, but everyone understands that the OP is in the UK, right? Single phase (not split phase) 230V or 240V depending on where he is.


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## Rich83 (May 17, 2021)

tabora said:


> I almost hesitate to mention this, but everyone understands that the OP is in the UK, right? Single phase (not split phase) 230V or 240V depending on where he is.


Yes correct single phase 230v 50Hz sorry i probably should have made that clear. Gen plate actually says 220v but ive ramped it upto 240 on the avr which i assume is ok. I have overload mcb's and i have no intention of overloading it assuming raising the volts slightly would reduce the poss kva very slightly at the same rpm??? (Not relavant for this chat i guess)


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## iowagold (Jan 22, 2020)

well if it is single phase 230v 50hz it is L1 L2 design.
and no neutral..
just earth ground on the chassis.
unless it is a multi country wired gen set.

so if you are to use the gen set as a stand alone construction gen you need an earth ground stake at the gen set.

if it is to be used as a home power back up with a proper interlock to the main breaker panel in the house
it will get the earth ground from the house panel.

check the house wiring to make sure it is correct as well as make sure your interlock and generator inlet is all wired correct.


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## Rich83 (May 17, 2021)

Ok so can i earth down the proposed neutral? My plan is to connect to the house board/ earthing when supplying the house via the generator change over switch and use a stake at the gen for any isolated supplies like a simple extention lead when not attached to the house. Question is will it damage the gen by grounding one side?


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## iowagold (Jan 22, 2020)

snap some pix of this gen set, and the connection panel for us.


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## Rich83 (May 17, 2021)




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## Rich83 (May 17, 2021)

Ok so today i gave up waiting and put a lead from neutral to earth with a timy 3 amp fuse in line. Grounded perfectly and did not blow the fuse. I put a 10kw pool heater and 1kw pump on and volts were good, neutral was about 0 volts and 3 amp fuse did not blow!! I think im good to hard wire the neautral down and test the protection and i thinks it seems all good. Very happy with that! Engine was a bit smokey though at full load!!!!


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## iowagold (Jan 22, 2020)

check the air filter make sure it is clean.
and make sure the smoke is not getting back in to the fresh air intake.
it will cork up an air filter fast!
try some fuel treatment for ctane booster.
several out there and most work well
not sure on the brands for uk
lucas makes a good one
howes
and there are several others here in the states.
pm me if you need links

check the grade on the diesel fuel...
here in the states we have summer and winter fuel..
different blend.

oh yea check the thermostat make sure it is coming up to temp on the engine.
diesels like heat to work right.
some where about 90.5 deg C or 195 deg f is perfect depending on the coolant.


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## Rich83 (May 17, 2021)

Ok perfect will do thanks, havnt had chance to run it for long so a good run will probabbly do it a world of good. Yeah air filter is new and exhaust exits the other side so thats all clear. I have run it fair bit but not for longer than 10 mins at a time amd not under load, before that it was stood for lots and lots of years. Its been well flushed through engine flush and filters replaced, all fuel and filters flushed and rrplaced obviously. Coolant and water pump flushed and replaced, new hoses and temp sensor etc. Starts and runs great. Just the smoke now. I know it can be adjusted on the injector pump but hopefully wont need to get into that.


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## iowagold (Jan 22, 2020)

darn exhaust like to get back in the air filter unless you have a tall stack...
some where i have a pix of a brand new zero hour skid loader air filter impacted with soot at 50 hours!
the stack was too short..
started that loop thing for no air so more soot!
it does not take long to cork a diesel air filter!


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## Rich83 (May 17, 2021)

Maybe i will give that a bit of special attention when i get close to finishing it, i see no reason why i cant extend it up as high as i want within reason


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## iowagold (Jan 22, 2020)

yup!
or look in to a scrubber for the exhaust...
unless you have a connection for one on the cheap they run bucks as new!
i would just do a stack up and maybe some baffle cones like they use for drag racing to help on the noise and after burn.
and they have those tractor flip top caps for rain etc when not running.

or use a rain cap like for natural gas.


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