Connecting a portable generator - advice

[Putmak]

To make life a little more comfortable during the grid power outages i am considering buying a small portable generator to "plug in" to the house circuits when needed, and "unplug" when the main power returns. Not understanding this subject i have no idea if 1 this is at all possible ?, and 2 if it is how would you do this, and what hardware would be required ?.

 

Advice gratefully received.    

[wayned]

Yes it's feasible and fairly easy to do.  I have a setup that would work just fine.  My incoming PEA supplied power Goes to a 100 mp "knife" switch before it goes to the CU.  The output of the "knife" switch goes to the main circuit breaker in the CU and also to a 30 amp waterproof IP44 socket.  The output of the generator would have the mating IP44 plug, like this, but mine is 32 amp not 16 amp: http://www.lazada.co.th/fsh-16-amp-3-pin-plug-amp-wall-mounted-socket-waterproof-220v-250volt-ip44-4200827.html?spm=a2o4m.search.0.0.2607039V8TMXG&ff=1

 

Nothing is automatic, when the power goes off you would have to turn off the "knife" switch, plug in the generator and start it so a handy fully charged LED flashlight would also be required.  When the power came back on you just reverse the process.  I installed it to do the same as you want but have never bought the generator, but I do use the socket to connect a welding machine when I need it.  The total cost would be somewhere around 2000 baht.

[Putmak]

9 minutes ago, wayned said:

Yes it's feasible and fairly easy to do.  I have a setup that would work just fine.  My incoming PEA supplied power Goes to a 100 mp "knife" switch before it goes to the CU.  The output of the "knife" switch goes to the main circuit breaker in the CU and also to a 30 amp waterproof IP44 socket.  The output of the generator would have the mating IP44 plug, like this, but mine is 32 amp not 16 amp: http://www.lazada.co.th/fsh-16-amp-3-pin-plug-amp-wall-mounted-socket-waterproof-220v-250volt-ip44-4200827.html?spm=a2o4m.search.0.0.2607039V8TMXG&ff=1

 

Nothing is automatic, when the power goes off you would have to turn off the "knife" switch, plug in the generator and start it so a handy fully charged LED flashlight would also be required.  When the power came back on you just reverse the process.  I installed it to do the same as you want but have never bought the generator, but I do use the socket to connect a welding machine when I need it.  The total cost would be somewhere around 2000 baht.

Hi Wayned, great information. Many thanks for your reply, and the Lazada link too. I was expecting it to be manual procedure to plug in and unplug the generator, so no probs there. All i need to do now is find an electrician who is capable of setting this up...!!  

 

All the best, cheers.. 

[wayned]

Here's the link to the 32 amp connector that I used: http://www.lazada.co.th/fsh-3pin-plug-wall-mount-socket-32a-amp-blue-4394532.html?spm=a2o4m.search.0.0.5fb7660bkNxw54&ff=1

 

60 0r 100 amp "knife" switches should be available at any electrical supply store.

 

So you would need

1 each knife switch, you could use a 63 amp circuit breaker and enclosure instead of a knife switch.

1 each 32 amp socket

1 each 32 amp plug

16 or 25MM2 wire to go from the knife switch to CU and the 32 amp socket.

1 each qualified electrician to install it as you would be working with live power unless you disconnected it at the meter (which I do)

1 each generator

 

The parts, other than the generator , should be less than 2000 baht.  Finding a "qualified" electrician is another problem.

[Crossy]

The single most important thing to ensure is that you can NEVER end up with both the genset and mains supply connected at the same time. Firstly you don't want to feed power back into the grid (think of the guys trying to get your power back on) and secondly there will only be one winner in the epic battle between the supplies (it won't be the genset).

 

What do you intend running? This will determine the size of genset you need.

 

There are a few threads on how to arrange transfers, both simple and manual and less simple and automatic.

 

[Putmak]

On 23/10/2017 at 7:06 AM, Crossy said:

The single most important thing to ensure is that you can NEVER end up with both the genset and mains supply connected at the same time. Firstly you don't want to feed power back into the grid (think of the guys trying to get your power back on) and secondly there will only be one winner in the epic battle between the supplies (it won't be the genset).

 

What do you intend running? This will determine the size of genset you need.

 

There are a few threads on how to arrange transfers, both simple and manual and less simple and automatic.

 

The idea is for emergency use only. Perhaps just a few hours when there is a power cut. I’ll need it for some domestic lighting, fridge, internet....air con etc can wait until mains is back on. I would just want a simple manual plug in/un plug connection. Any tips gratefully received. Thanks.

[lopburi3]

The issue for such use is that the gen set to be reasonable price can not be sized to provide full house power so if you attach without limitations you must go around and turn off those air conditioners and such before you switch to generator power.  Not impossible to do - but expect to miss at some point and kill the generator (not a nice sound if you can not remove load before it dies - even if it has more lives).  Probably best to have set breakers to have on and others to have off in main box and double check that each time.

[Putmak]

43 minutes ago, lopburi3 said:

The issue for such use is that the gen set to be reasonable price can not be sized to provide full house power so if you attach without limitations you must go around and turn off those air conditioners and such before you switch to generator power.  Not impossible to do - but expect to miss at some point and kill the generator (not a nice sound if you can not remove load before it dies - even if it has more lives).  Probably best to have set breakers to have on and others to have off in main box and double check that each time.

Ok, many thanks.

[bankruatsteve]

All gensets that I have had and seen will have a CB that will trip on overload which depends on gen size.  For example, a 2 KVA will have a 9 amp breaker.  If it trips, you just reduce load and reset the breaker.

 

BUT - connecting by plug into a socket contains several potentially lethal hazards that can be avoided by connecting to a transfer switch instead.  That is simple to install and not that expensive.  Do it properly and you will be glad you did.

 

[lopburi3]

I well recall running a 2.5 genset into the ground in Kaduna, Nigeria when people forgot to turn off the air conditioners in the Consulate back in the summer of '67 - but claimed that they had (switch by pull pole from ceiling).  All other experience was with larger generators which would sync for transfer.  Obviously that small generator did not have a working breaker.  Or someone decided it was not needed and could be sold.

[Putmak]

40 minutes ago, bankruatsteve said:

All gensets that I have had and seen will have a CB that will trip on overload which depends on gen size.  For example, a 2 KVA will have a 9 amp breaker.  If it trips, you just reduce load and reset the breaker.

 

BUT - connecting by plug into a socket contains several potentially lethal hazards that can be avoided by connecting to a transfer switch instead.  That is simple to install and not that expensive.  Do it properly and you will be glad you did.

 

Thanks for the advice...I guess a quality electrical supplier will know what a “transfer switch” is if I describe what I plan to do. Buy the way I repeat I know nothing about electrical supply installation so will have someone who knows what he is doing install it for me. 

[Crossy]

3 minutes ago, Putmak said:

Thanks for the advice...I guess a quality electrical supplier will know what a “transfer switch”

I wouldn't be so sure

 

If you're going manual, this has to be the cheapest, safe, way of doing it.

 

https://www.aliexpress.com/item/2P-63A-MTS-Dual-power-Manual-transfer-switch-Circuit-breaker-MCB-50HZ-60HZ-400/32786129292.html

 

Two 63A breakers interlocked so only one at once can be closed.

 

You can either re-organise your wiring so that only the stuff you want on genset is on the transferred side,  or mark those breakers to be turned off when on genset.

 

Being a lazy sod I made everything fully auto, auto start and auto load-shed.

 

 

 

 

 

[Lamkyong]

with respect sir    not lazy just the most efficient safer way to do the job

 

reading other posts made me   confused/ worried  especially  the one about i know nothing/very little  about electric circuits  but i guess thats why people post about such subjects   for advice albeit some advice sometimes some what sketchy  thanks for your input

[Crossy]

6 minutes ago, Lamkyong said:

not lazy just the most efficient safer way to do the job

To be honest, anything other than at least semi-automatic becomes old very quickly if you have anything other than the occasional power failure. Of course it's always dark and raining when the power goes off, sit in the dark or get wet?

 

Our genset runs maybe twice a month, a bit more in the wet season when the flash-and-bang is about. In reality we rarely notice it start other than the aircon stopping.

 

[Putmak]

59 minutes ago, Crossy said:

I wouldn't be so sure

 

If you're going manual, this has to be the cheapest, safe, way of doing it.

 

https://www.aliexpress.com/item/2P-63A-MTS-Dual-power-Manual-transfer-switch-Circuit-breaker-MCB-50HZ-60HZ-400/32786129292.html

 

Two 63A breakers interlocked so only one at once can be closed.

 

You can either re-organise your wiring so that only the stuff you want on genset is on the transferred side,  or mark those breakers to be turned off when on genset.

 

Being a lazy sod I made everything fully auto, auto start and auto load-shed.

 

 

 

 

 

Ok, thanks for that. At least I know what a transfer switch looks like. 

[bankruatsteve]

Just to say,  most transfer switches don't look like that.  Most will have just one lever that transfers input from gen or main to the output (CU).  Not sure how available they are here (at the "Home" places) but for sure can get from Ebay/UK (as I did) and probably more these days.

[lopburi3]

30 minutes ago, bankruatsteve said:

Just to say,  most transfer switches don't look like that.  Most will have just one lever that transfers input from gen or main to the output (CU).  Not sure how available they are here (at the "Home" places) but for sure can get from Ebay/UK (as I did) and probably more these days.

I would have said the same but box types seem to have been replaced by breakers these days and breaker can even be obtained on Lazada or AliExpress.

Type I remember.

[RichCor]

I'll just leave this here then...

 

a BigClive discussion and tear-down of an Automatic Transfer Switch
By RichCor, November 2 in The Electrical Forum 

 

 

Yes I'm annoying, and shameless

[Crossy]

Indeed, there isn't a generic appearance for a transfer switch.

 

They come in many shapes and sizes, auto and manual but they share one common function.

 

This could be used as a transfer switch too https://www.aliexpress.com/item/32A-Two-Pole-Double-Throw-Knife-Disconnect-Switch/1820898331.html

 

 

[lopburi3]

3 hours ago, Crossy said:

Indeed, there isn't a generic appearance for a transfer switch.

 

They come in many shapes and sizes, auto and manual but they share one common function.

 

This could be used as a transfer switch too https://www.aliexpress.com/item/32A-Two-Pole-Double-Throw-Knife-Disconnect-Switch/1820898331.html

 

 

Indeed - a much heavier duty version of such was normal to see when I was using some 50 years ago.  Not much to fail in such a system.

[Putmak]

On 23/11/2017 at 9:02 AM, lopburi3 said:

Indeed - a much heavier duty version of such was normal to see when I was using some 50 years ago.  Not much to fail in such a system.

So I guess mains connected to one side, the generator to the other, and the middle connections go off to the domestic circuit.  And the position of the lever determines whether it’s main or generator power....just one point, I can’t see any earth connections ?....

[Crossy]

Just now, Putmak said:

I can’t see any earth connections ?

That's because you NEVER switch the safety earth.

[Putmak]

Just now, Crossy said:

That's because you NEVER switch the safety earth.

Ok, how would the earth be connected in this case.....please forgive my ignorance....

[Crossy]

Just now, Putmak said:

Ok, how would the earth be connected in this case.....please forgive my ignorance....

Just connect all the earths together and to the rod.

[Putmak]

Just now, Crossy said:

Just connect all the earths together and to the rod.

Ok.....got it. Thanks. Ill not be connecting up this kit by the way....but just need to understand it a bit more.

[observer90210]

On 22/11/2017 at 1:40 PM, lopburi3 said:

I would have said the same but box types seem to have been replaced by breakers these days and breaker can even be obtained on Lazada or AliExpress.

Type I remember.

but would you trust AliExpress for sensitive electrical stuff ?

[Crossy]

3 minutes ago, observer90210 said:

but would you trust AliExpress for sensitive electrical stuff ?

I've bought lots of stuff from AliExpress, if you go for trusted names and high reputation sellers you will be fine.

 

My earlier link to the Tomzn switch is from their official store. Tomzn are a well known Chinese name. I actually bought one of these switches, quality looks fine, interlock works well.