Ballpark Figure - Connecting Generator to house

[greggpb]

Any one what a ball park figure would be for a Electrictian to connect a Generator to the House supply?


House is 3 phase and single phase generator is is going to be connected to one of the phases, this probably entails a manual cut over switch ?

 

[Sonic2k]

The manual change over switch costs in the region of R680
I did the exact install you need, for a client... total cost was R1500.. took me 45 minutes to do it.

 

[greggpb]

The manual change over switch costs in the region of R680
I did the exact install you need, for a client... total cost was R1500.. took me 45 minutes to do it.

Are you near the mountain(cpt) or the thunder(jhb) ?

 

[BuckRogers]

I paid about R3K.
This included a manual transfer with indicator neon light, outdoor "caravan" type connector, a connecting cable and a certificate of compliance.
The electrician said it could get even more expensive if the DB does not have an open conduit.

 

[The_MAC]

One thing I learnt with electricians is that there are many of them that try to take you for a ride.

They all have an hourly rate, so all you need to do is figure out what components are needed to achieve what you want, calculate the cost of those components separately (you can probably buy most of them at Builders or an Electrical Wholesaler), add an estimated number of work hours and that should give you a pretty good idea of the cost.

Some of them come out and just shoot a random number.. And charge 3 times more than what is required.

 

[ProfA]

One thing I learnt with electricians is that there are many of them that try to take you for a ride.

They all have an hourly rate, so all you need to do is figure out what components are needed to achieve what you want, calculate the cost of those components separately (you can probably buy most of them at Builders or an Electrical Wholesaler), add an estimated number of work hours and that should give you a pretty good idea of the cost.

Some of them come out and just shoot a random number.. And charge 3 times more than what is required.

Same as plumbers.

 

[heartbroken]

If you have a bit of electrical know how and don't mind scratching around in the roof you can install everything yourself and then just pay a sparky the R900 odd for a CoC inspection.

 

[greggpb]

I wouldn't do it but I wouldn't mind someone running through what would be needed, so I dont get owned.


The way I understand it is a manual 3 phase switchover connected between the prepaid meter and the mail db, with a connection
going to the generator ?


Nothing more really, and then you need to do some breaker moving to get the right items on the right phase for the generator ?

 

[Gnome]

Step 1:
Everything you want on generator power needs to be on one phase.
What this involves:
This may involve moving some of your electrical components to other phases, the rule imposed by SANS is the phases must be balanced as realistically as possible.
For some installations this can mean you need an extra RCD (or "earth leakage" as SA likes to call them)

The Eskom supply, which runs to your Eskom contactor should NOT be wired via an RCD. The RCD is added AFTER the contactor. It should be on a MCB before the contactor however, rated to the current capacity of the wiring.

Step 2:
Depends on the installer, but I would use a 2p or 3p contactor (p = pole) x2 with mechanical interlock
One contactor coil is powered by Eskom power, the other contactor is powered by generator. You also need a 1P auxiliary to prevent the generator contactor from turning on if the generator & Eskom are active at the same time.
Most contactors come with an auxiliary, almost every mechanical interlock unit also comes with one.

Generator output run to the generator contactor, should have a MCB before the contactor rated to the current capability of the *CABLE* not your generator capacity.

Step 3:
Wire the two contactor outputs to a single MCB (double pole) + RCD, and from there wire all the circuit breaker MCBs to that RCD.

At this point the automatic change over is complete.

Summary:
Eskom Power -> Double Pole Breaker -> Contactor -> Backup Power Double Pole Breaker -> RCD
Generator Power -> Double Pole Breaker -> Contactor -> Backup Power Double Pole Breaker -> RCD

Highlighted sections are shared.

Shared section:
Backup Power Double Pole Breaker -> RCD -> Single Pole breakers (Lights for example, Plugs, etc.)

In each case the breakers are rated for the CABLE. Your generator should have its own ability to cut off in the event of over current. The breakers are there to protect the wires, not your generator (so you may need a circuit breaker just for the generator)

Technically you can make the Backup Power Double Pole Breaker rated to your generator output! That would probably be your wisest choice.

Step 4:
Depends on the generator, you need to wire the generator to auto-start during a power outage.
This is not a *must* but will require you start the generator manually.

Can think of a way to do this with a relay, but honestly it really depends how the generator starts. Like is it a push button, let go and it starts itself. Is it a push and hold until it starts.
Both are trivial to make auto-start for with a few relays.

Also consider the housing of your generator, petrol levels, etc. You may not want auto-start.

 

[Gnome]

The manual change over switch costs in the region of R680

The price of changes to the DB depends on what needs to be changed. So I wouldn't say it as cut and dry as Rx. Especially for an existing 3 phase install...

For the change-over however, for R680 you can almost afford to buy two contactors and a mechanical interlock which would be automatic change-over.

Granted the contactor would meet the requirements for AC1 (resistive loads) not AC2/3 (inductive motors eg. squirrel cage motor stop/start, etc.).
For AC3 I think you would need about R1500 just for the contactors.

 

[greggpb]

Step 1:
Everything you want on generator power needs to be on one phase.
What this involves:
This may involve moving some of your electrical components to other phases, the rule imposed by SANS is the phases must be balanced as realistically as possible.
For some installations this can mean you need an extra RCD (or "earth leakage" as SA likes to call them)

The Eskom supply, which runs to your Eskom contactor should NOT be wired via an RCD. The RCD is added AFTER the contactor. It should be on a MCB before the contactor however, rated to the current capacity of the wiring.

Step 2:
Depends on the installer, but I would use a 2p or 3p contactor (p = pole) x2 with mechanical interlock
One contactor coil is powered by Eskom power, the other contactor is powered by generator. You also need a 1P auxiliary to prevent the generator contactor from turning on if the generator & Eskom are active at the same time.
Most contactors come with an auxiliary, almost every mechanical interlock unit also comes with one.

Generator output run to the generator contactor, should have a MCB before the contactor rated to the current capability of the *CABLE* not your generator capacity.

Step 3:
Wire the two contactor outputs to a single MCB (double pole) + RCD, and from there wire all the circuit breaker MCBs to that RCD.

At this point the automatic change over is complete.

Summary:
Eskom Power -> Double Pole Breaker -> Contactor -> Backup Power Double Pole Breaker -> RCD
Generator Power -> Double Pole Breaker -> Contactor -> Backup Power Double Pole Breaker -> RCD

Highlighted sections are shared.

Shared section:
Backup Power Double Pole Breaker -> RCD -> Single Pole breakers (Lights for example, Plugs, etc.)

In each case the breakers are rated for the CABLE. Your generator should have its own ability to cut off in the event of over current. The breakers are there to protect the wires, not your generator (so you may need a circuit breaker just for the generator)

Technically you can make the Backup Power Double Pole Breaker rated to your generator output! That would probably be your wisest choice.

Step 4:
Depends on the generator, you need to wire the generator to auto-start during a power outage.
This is not a *must* but will require you start the generator manually.

Can think of a way to do this with a relay, but honestly it really depends how the generator starts. Like is it a push button, let go and it starts itself. Is it a push and hold until it starts.
Both are trivial to make auto-start for with a few relays.

Also consider the housing of your generator, petrol levels, etc. You may not want auto-start.

Firstly, Thank you Gnome for the very detailed answer and adding some indepth knowledge to the forum, I wish we could find electrical contractors who dealt in such details and appose to "yah we just connect here, dont worry about that"..


secondly, are the contactors and extra breakers necessary if I was going to run a manual switch over ?

Thanks Gregg

 

[Johnny_Q]

Below is this quote I received to have the generator installed into DB

Scope of Work
Supply and install a suitable flexible cable from the load-side socket on the generator to a new surface-mounted weatherproof enclosure adjacent to the generator.
This enclosure will have an SABS approved double pole isolator / mcb combo unit.
Supply and install an SABS approved copper earth electrode adjacent to the generator and ensure that the generator and the earth terminal are suitably bonded to this electrode.
Install some 12m of suitable screened cable from the new enclosure adjacent to the generator to a new surface-mounted 63amp manual changeover switch.
This switch will be fixed to the cupboard next to the remote mains isolator behind the back door.
Pilot status indication lamps are to be installed at the changeover switch.
On completion of this task, test and commission the system.

Pricing / Budget

Materials R3 737-50
Labour R3 200-00

I am currently waiting for the second quote to compare if these cost are in line

 

[Gnome]

Firstly, Thank you Gnome for the very detailed answer and adding some indepth knowledge to the forum, I wish we could find electrical contractors who dealt in such details and appose to "yah we just connect here, dont worry about that"..

secondly, are the contactors and extra breakers necessary if I was going to run a manual switch over ?

Thanks Gregg

The above is for a automatic change-over, I quickly did some checking to see how a manual switch over would be done.

For reference here are some manual change over switches:
http://www.acdc.co.za/getPage.php?page=183

For a 32A 2 Pole change over (AN5613100) it is R590 (probably ex. VAT)
For a 63A 2 Pole change over (AN5616100) it is R902

Generally I would at minimum do the following:
Eskom power (Main switch) -> 30 Amp Breaker (for 32A change over) -> Change over
Generator (power cable that came from generator, this is in the DB box where the Eskom Power is) -> 30 Amp Breaker -> Change over

You need a light to show power on Eskom and Generator, but they can be done cheaply (more on this later).
You should put your change over switch RIGHT next to your DB Box.

Change over -> Circuit breaker rated to your generator max power, no more than 30 amp breaker above -> Surge protector (optional) -> RCD/Earth Leakage -> All the stuff you want on the generator (each must have its own circuit breaker as usual, eg. single pole circuit breaker for plugs, lights, etc.

Honestly, these circuit breakers are cheap. Why skip on them?
Live Copper delivers free for orders over R500 and I've used them a few times now, they are really awesome btw.

The surge protector is optional, but it is cheap and it does help! Especially with spikes when switching the supplies and such.

This setup has an RCD/Earth Leakage which makes it really safe so that you won't get electrocuted.
The other circuit breakers are there to protect the wire, change over switch, etc.

Even the 30amp breakers above are probably a bit high for the 32A change-over so ideally 63A change-over if you can afford it.

All this goes in your main panel. Except the change over switch which is next to the panel.

The generator power cable obviously goes to the generator. You need an isolator at the generator also. This is right next to where the generator is installed in a fixed position.

 

[greggpb]

Thanks very very much for the the additional information. Will fork out the extra for a quality install the challenge is finding really top class guys to do the install, I paid quite a bit for a good inverter generator(eu30is), so no point is risking it with a cheap install.

Cool seem to have my head around around what needs to be done now, this is the plan as it stands

My setup from a birds eye view



As you can see here the eskom supply connects to my house at the front wall(red Box) and the prepaid meter is there as well.



I was expecting to put the generator just behind that(green box) as I could drill directly through and mount a water proof box on the other side of the wall with the changeover and build a enclosure for the generator

Why does the change over switch (63A one ) need to be close to the DB ?



Then main DB(blue box) Look like this

 

[Gnome]

Thanks very very much for the the additional information. Will fork out the extra for a quality install the challenge is finding really top class guys to do the install, I paid quite a bit for a good inverter generator(eu30is), so no point is risking it with a cheap install.

Wow nice generator! With a good generator like that you may want to have automated switch over in the future...

Look those breakers are really cheap IMO and Crabtree make good quality products. No need to skimp to save R200 right?
Safety first. You don't want your place to burn down or worse for someone to get electrocuted and R200 extra doesn't break the bank.

Just my 2c.

View attachment 238926

As you can see here the eskom supply connects to my house at the front wall(red Box) and the prepaid meter is there as well.

Ok I get your setup now.

IMO, the best setup for you:
View attachment 238928

I would add a small breaker box right there next to the meter. But guess you can just add more breakers there, it just seems unsafe...
In SA your power has to go left to right, top to bottom (incoming top, load bottom).
There are some exceptions but to make things simpler, I would do the following.
Move the meter if possible all the way to the left or right.
Add a small DB box. In there you can add your main breaker, neutral and ground (that is haphazardly out in the open there).

These aren't a must however, the more important part is:

Add another breaker after one of your main breaker (branches from the top of the Red/Yellow/Blue). Btw. no idea why it is wired bottom to top. That is strange for SA...

Your neutral is right there next to the meter, so you run a cable from that neutral bus bar to the breaker.
The output of that breaker goes to your change over switch.

Bring generator cable in and run through similar breaker. With generator live & neutral.
Wire generator earth to your main earth over there.

Run the output of the switch over into your house.

EDIT: I don't know why but I'm wondering if your breaker was wired first then the meter. That doesn't make sense, but can and should be tested with a multimeter (if it is turned of is there power at the bottom of that main breaker?). That would make it super easy for you to steal power, LOL.


You can use the bottom section here for your backup power circuit:
View attachment 238930
The power wire from the generator can run straight into a double pole breaker (rated to the generator output) and then into a surge protector (optional) and finally your RCD.

Then simply move your stuff from the other two parts of the DB above to your backup section that you want on backup power..

Things to take note of:
1) Ensure your load is balanced across all 3 phases as much as possible. This can mean moving some of the breakers of the two top sections around wire wise.
2) Ensure you don't try wire ANYTHING with a 3 phase breaker to the backup power section. EVEN if it is really single phase. If something has a 3 phase breaker SANS says it is 3 phase regardless if it is actually single phase at the other end. (3 single phase appliances, etc.) The assumption by an installer is it is safe to wire 3 phase appliances there and then it will go boom.

Should be pretty safe and solid setup. Your setup looks pretty simple to wire up actually.

You don't seem to have anything that uses 3 phase however.
All of your middle section is powered by one phase. (probably all your plugs)
The stuff on top is powered from other phases (almost certainly) but not protected by RCD (earth leakage). Probably those are your geysers, lights, stove, oven and possible pumps and stuff.
Can't tell what is written on them but it is pretty clean install.

 

[greggpb]

First night with generator running .. Pricless

 

[Gnome]

First night with generator running .. Pricless

Pics of final install?

 

[greggpb]

Will take some shots tonight,