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Thread: Small generator connection

  1. #1
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    Small generator connection

    So many calls from desperate customers ...wanting to connect a small genrator to the house.

    NO VOV GENERATORS CAN BE CONNECTED TO THE HOUSE DIRECTLY.

    So I came up with a solution which I beleive is the safest way to do it without rewiring the entire house and fitting dedicated and non dedicated supplies.

    This is how I have wired my own house.

    Drilled a hole into the bottom of my meter ... installed 2 x 25 mm adaptors with a short piece of 25 mm sprag (this must be sealed if out in the weather)

    Mounted a 12 way IP 67 DB.

    The DB is fitted with an idicator light to shows the mains power is on ... a 63 A changeover switch (the meter has a 60 amp breaker)

    16 mm wires from the meter to the top of the changeover switch.

    16 mm wires from the bottom of the changeover switch back into the meter box which are joined to the house wires feeding the main DB using ferruls.

    A 32 amp wall mounted male plug top is installed belew the changeover DB (fitted with a cap when not in use)

    4 mm wires feeding from the plug into the changeover DB to the doublew pole 32 amp geyser combo type breaker/ isolator then from the combo to the generator input on the changeover switch... the neutral wire is bonded at the input side of the combo breaker/isolator to the main earth with an indicator light mounted next to the changeover switch to indicate when the genertor is feeding power ... there is also a voltmeter and 100 amp panel meter mounted on the side of the changeover panel for the customer to monitor the load draw from the house ... so that he can choose which circuits he wants to power.

    The generator (8 kva) has 10 m of 4 mm trailing cable (for extra protection) connected directly to the 30 amp breaker mounted in the generator via a compression gland with a 32 amp female plug coupler at the other end ... I didnt fit a 32 amp socket outlet on the generator because during the last load shed ... the vibration from the generator caused the plug to eventually fall out ... causing a few issues.

    I cant think of a safer easier way to do this ... without it becoming a massive cost to customers.

    It is a manual changeover and circuits in the house must be isolated to prevent overloading ... which can be monitored by the current meter mounted on the side of the changeover panel.

    We will be upgrading the main DB soon ... ther ewill be a voltmeter and ammete rattached to the front so easy power management.
    Last edited by ians; 14-Jun-21 at 10:26 AM.
    Comments are based on opinion...not always facts....that's why people use an alias.

  2. #2
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    I have a minor concern ... the indicator lights and voltmeter don have fused protection ... but I am thinking maybe it is not reuqired because they are only 100 mm long 1.5 mm wires ... in the fault free zone. ... I will phone a friend to verify this ... other wise 3 fuse holders with 3 1 amp fuses should be fine.
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    Installation complete ... I didnt bond the neutral and earth ... did a few tests and it indicated no earth ... so I decided to bond in the changeover DB ... I did consider doing it in the generator where I connect ed the 4 mm trailing cable ... but was concerned about the fact that a generator used and a mobile units doesnt have the N and E bonded.

    Instead I ran the neutral to the earth stud and from there to the the top of the 32 amp combo breaker.

    A note ... I took the cable from the meter circuit breaker ... down to the 32 amp plug and back up into the meter ... then realised that while the generator was running the meter was turning ... so I had to change it ... out the meter load side of the meter ... down to the changeover switch and back up to the meter joined using ferulles.

    Customer very happy ... next step to replace the main DB (we have rewired the house and made the house smart comapatible ... ie neutral in the switch boxes) ... fit an inverter and bactteries ... then at a later stage ... solar panels.
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  4. #4
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    Quote Originally Posted by ians View Post
    Installation complete ... I didnt bond the neutral and earth ... did a few tests and it indicated no earth ... so I decided to bond in the changeover DB ... I did consider doing it in the generator where I connect ed the 4 mm trailing cable ... but was concerned about the fact that a generator used and a mobile units doesnt have the N and E bonded.

    Instead I ran the neutral to the earth stud and from there to the the top of the 32 amp combo breaker.
    .
    Not sure if I misunderstand what was said above.

    Joining neutral and earth at the end of the trailing cable or at the changeover DB is basically the same thing.
    If in the change over DB , do I then understand that when running on incoming municipal supply the earth and neutral is bridged in your DB as well ?

  5. #5
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    I will try expalin a little better.

    At the generator - I drilled ahole into the side of the power box (with the plugs switches ... etc) ... fitted a gland and connected the neutral to the neutral wire from the alternator and the earth wire to the earth wire from the alternator and the earth stud on the generator ... the live I connected to the bottom of the 30 amp circuit breaker (no bonding between N-E)

    The trailing cable has a 32 amp socket outlet attached on the end (no bonding N-E) ... which plugs into the wall mounted plug top.

    The wall mounted 32 amp plug top - the neutral and earth go to the earth bar in the changeover DB ... then the neutral goes from the earth bar to the N at the top of the 32 amp combo breaker ... the live goes from the plug top pin to the L on the top of the 32 amp combo ... then from the bottom of the combo breaker to the G / GN input on the changeover switch and to the indicator light.


    I was going to fit a 32 amp plug socket in place of one of the 16 amp 164-1 sockets and wire it to the breaker directly with 4 mm wire ... however after my incident the other night during load shedding ... my plug fell out the generator ...causing all sorts of problems because it didnt just fall out ...it worked loose slowly.

    I was going to bond the neutral and earth at the generator in the power box ... but I decided against it ... the reason ... generators are supplied without it bonded ... as I am typing I am thinking maybe this generator is VOV ... I will go back and check tomorrow and measure the voltage between L-N-E/ L-E. ... just to make sure ... from what I understand ... if the generator is not VOV ,... the N and E should be bonded at the alternator ?
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  6. #6
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    A good example of a typical electrical installation in SA.


    https://www.youtube.com/watch?v=CE0B...ecologicaltime
    Comments are based on opinion...not always facts....that's why people use an alias.

  7. #7
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    Anyone have a list of VOV generators sold in SA ...which should not be connected to the electrical installation?

    And maybe a list of generators which can be connected ... in the 5 -10 kva range ( the most common sold )

    For example -

    Yamaha

    Honda

    Ryobi

    Grip
    Comments are based on opinion...not always facts....that's why people use an alias.

  8. #8
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    Another lesson learnt ...

    The customer goes to the local Builders and enquires about a generator to connect to the house ... the sales guy shows him one on special ... with ample capacity ... 7500 watts.

    The customer contacts his electrician and books a ticket to connect it to the house.

    The electrician is aware of the VOV issue ... but the customer informs him that the generator is the wired correctly as per the generator supplier and there is a label on the generator which indicates that it is compliant with "SANS 1007:2010 STANDARD" ... everyone is happy. ( I havent read the PDF yet ... I am assuming it doesnt say what I am expecting it to say)

    https://store.sabs.co.za/pdfpreview....0b&preview=yes

    The electricians installs a change over switch and all the necessary equipment to comply with the basic conditions required for a generator.

    Everyone is excited to see how it is going to handle the load ... the startup and switch on procedure is covered 3 times to make sure it is done properly.

    All systems go -

    Until you start testing ....

    L-N = 230 Volts

    L-E = 82 volts (already a problem)

    E-N = 148 volts (at this stage ... you realise why you havent been doing these small generator installs)

    plug the plug tester into a socket outlet in the house ... only 2 lights on ... which indicates "NO EARTH" just what you expected ... and the earth leakage tester will not trip.

    This is when you say as little as possible ... quickly take the customer cash and run like hell.

    OR you bond the neutral to earth show the customer that everything is sorted ... take the cash and run like hell ... while heading for the door ... block his number because when the alternators burns out due to circulating currents ... the generator suppler sales person who told you the generator could be connected to the house will be long gone.

    Please correct me if I am talking shyte ... a GRIP 7,5 KVA generator cannot be connected to the house electrical ... reasons ... it is an imported unit which doent comply to the relavant standards for operating as a standby generator.

    You need to understand the difference between an standby generator (designed to connect to electrical installations) and a mobile generator (not designed or wired to connect to an electrical installation VOV type)
    Comments are based on opinion...not always facts....that's why people use an alias.

  9. #9
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    Hi Ian
    I posted a couple of days ago that the Grip alternator bought at builders is NOT vov wound and is suitable for use as a standby.

    I cannot vouch for any other make, but Grip passes the test.

    Peace out .. Derek

  10. #10
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    Talk about passing the buck ... I contacted Gentech industries ... sorry we cant help you builders import directly ... we only sell product ... we cannot offer technical support ... so they gave me another number ... contacted that number ... sorry we cant help you we only selll units ... they gave me another number ... tried a few times the person doesnt answer the phone.

    According to Gentech industries ... they havent had any issues with the generators being connected directly to the house.

    The way forward ... contact Builders and get it in writing ... win win for everyone.
    Comments are based on opinion...not always facts....that's why people use an alias.

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