Generator switch wiring help

[Scott1978]

Hello all.

I have been asked by a customer to install a generator changeover switch so he is protected in the event on a power cut. He is proposing a 4kva generator. Just to offer enough power for his fishpond and the odd socket for a fridge etc.

I have seen lewden sell a 125amp switch which will do the job.

I wanted to ask if anyone has installed one and can offer helpful advice. Being honest. I have not installed this set up before. Though seems straight forward.

Thanks

S

 

[Lucien Nunes]

In wiring terms, installing a transfer switch is indeed straightforward. More complex is ensuring that the existing protective measures of the installation are compatible with generator supply. The single greatest factor is likely to be the fault loop impedance.

 

[Crizco]

Hello all.

I have been asked by a customer to install a generator changeover switch so he is protected in the event on a power cut. He is proposing a 4kva generator. Just to offer enough power for his fishpond and the odd socket for a fridge etc.

I have seen lewden sell a 125amp switch which will do the job.

I wanted to ask if anyone has installed one and can offer helpful advice. Being honest. I have not installed this set up before. Though seems straight forward.

Thanks

S

Hi Scott
I have just finished wiring my changeover switch for my generator. I cut into the meter tails after the incoming meter, wired these into the changeover as well as the generator. Then ran new tails to the consumer unit.
Changeover switches are three way switched: incoming supply 1 / isolated / incoming supply 2.
Hope this helps.

 

[Scott1978]

Hi Scott
I have just finished wiring my changeover switch for my generator. I cut into the meter tails after the incoming meter, wired these into the changeover as well as the generator. Then ran new tails to the consumer unit.
Changeover switches are three way switched: incoming supply 1 / isolated / incoming supply 2.
Hope this helps.

Thanks crizco . That helps. Can I ask. Do you alter the earthing arrangement for the generator side.? Also I presume that you don’t change anything inside the consumer unit. The generator will feed in what it can and the domestic circuits will use what power is available..?
Did you fit a 16 amp socket on outside wall...?
[automerge]1586526652[/automerge]

In wiring terms, installing a transfer switch is indeed straightforward. More complex is ensuring that the existing protective measures of the installation are compatible with generator supply. The single greatest factor is likely to be the fault loop impedance.

Thanks lucien nines.

The exsiting system is tn-s. i presume I would need to ask the manufacturer about compatibility.? Sorry my knowledge of generation is not brilliant.

 

[Crizco]

Thanks crizco . That helps. Can I ask. Do you alter the earthing arrangement for the generator side.? Also I presume that you don’t change anything inside the consumer unit. The generator will feed in what it can and the domestic circuits will use what power is available..?
Did you fit a 16 amp socket on outside wall...?

The genny is a 9kva, so 32amp outlet and I wired direct to the changeover switch.
I did not modify the consumer unit (apart from new tails) and did not modify the earth.
I went on this advice for the earth:

Earthing arrangements to a generator and change over switch | on ElectriciansForums

Find Earthing arrangements to a generator and change over switch Advice and Help. How-to Earthing arrangements to a generator and change over switch in the UK Electrical Forum advice boards on ElectriciansForums.net | Free Electrical Advice - Electricians Forums: Electricians' Talk Forums...

www.electriciansforums.net

reread this and to clarify:

• the genny was a permanent installation
• genny earth was wired to the main earth busbar.

 

[Lucien Nunes]

and did not modify the earth

Crizco, out of interest, what is the earthing configuration when running on the DNO supply and when on the genny? What is the PSCC on the genny?

 

[Scott1978]

The genny is a 9kva, so 32amp outlet and I wired direct to the changeover switch.
I did not modify the consumer unit (apart from new tails) and did not modify the earth.
I went on this advice for the earth:

Earthing arrangements to a generator and change over switch | on ElectriciansForums

Find Earthing arrangements to a generator and change over switch Advice and Help. How-to Earthing arrangements to a generator and change over switch in the UK Electrical Forum advice boards on ElectriciansForums.net | Free Electrical Advice - Electricians Forums: Electricians' Talk Forums...

www.electriciansforums.net

reread this and to clarify:

• the genny was a permanent installation
• genny earth was wired to the main earth busbar.

Thanks. That info is good but I may have confused myself. In one breath it says you don’t need to necessarily disconnect the earth from the don supply but then you should supply a suitable means of earthing...

I’m just trying to find out is you should give the generator a earth rod or not. Does that make sense.?

 

[buzzlightyear]

just trying to find out is you should give the generator a earth rod or not. Does that make sense.?

yes the answer.Portable generators are useful for when temporary or remote power is needed. ... Thus, rather than connect to a grounding electrode system, such as a driven ground rod, the generator's frame replaces the grounding electrode. If these conditions do not exist, then a grounding electrode, such as a ground rod, is required.

 

[Scott1978]

yes the answer.Portable generators are useful for when temporary or remote power is needed. ... Thus, rather than connect to a grounding electrode system, such as a driven ground rod, the generator's frame replaces the grounding electrode. If these conditions do not exist, then a grounding electrode, such as a ground rod, is required.

Another question i have please... for sale there is 2 distinct different switches I can find on the internet. one is a rotary type with 3 positions Mains / off / generator.
The other seems to look like a 2 position isolator switch - up for mains, down for generator. (no off position)

any advice on which is considered better or safer? Do you need the 'off' position as a requirement or regulation ? Therefor, why would people sell the 2 position switch.

Thanks in advance..S

 

[davesparks]

Did you fit a 16 amp socket on outside wall...?

Hopefully not because that would be lethally dangerous, you must install an appliance inlet (plug) NOT a socket!
A socket would require a trailing lead with a plug on the end coming from the generator, the pins of the plug would be live when the generator is running!

Another question i have please... for sale there is 2 distinct different switches I can find on the internet. one is a rotary type with 3 positions Mains / off / generator.
The other seems to look like a 2 position isolator switch - up for mains, down for generator. (no off position)

any advice on which is considered better or safer? Do you need the 'off' position as a requirement or regulation ? Therefor, why would people sell the 2 position switch.

Thanks in advance..S

The ones which look like a main switch should have three positions with a centre off.
I would never fit a changeover switch without centre off for this sort of application, that could be a disaster if the switch doesn't guarantee total disconnection of one supply before connecting the other.

 

[Scott1978]

Hopefully not because that would be lethally dangerous, you must install an appliance inlet (plug) NOT a socket!
A socket would require a trailing lead with a plug on the end coming from the generator, the pins of the plug would be live when the generator is running!



The ones which look like a main switch should have three positions with a centre off.
I would never fit a changeover switch without centre off for this sort of application, that could be a disaster if the switch doesn't guarantee total disconnection of one supply before connecting the other.

Ha, Thanks davesparks. I did mean a inlet plug. such as this link..

Industrial Socket IP67

• IP20

www.toolstation.com

I thought the isolator main switch type must have a -off- position, however doesn't say it in any of the product descriptions. I will call up my supplier after easter and confirm it.

Thanks

 

[pc1966]

I thought the isolator main switch type must have a -off- position, however doesn't say it in any of the product descriptions. I will call up my supplier after easter and confirm it.

You get changeover switches for UPS bypass without a centre-off and with spring-assisted very fast switching, typically 10ms or so, so you can take the UPS off-line for maintenance without a noticeable break in power (so PCs don't reboot, etc).

However, that is a very bad idea for changing over from two independent supplies as the phase/frequency will not be matched and you might just end up damaging stuff. For generator use you really want something with a gap in changeover, and if that is a problem for critical stuff then they ought to be on a UPS to keep the supply happy.

 

[davesparks]

Ha, Thanks davesparks. I did mean a inlet plug. such as this link..

Industrial Socket IP67

• IP20

www.toolstation.com

I thought the isolator main switch type must have a -off- position, however doesn't say it in any of the product descriptions. I will call up my supplier after easter and confirm it.

Thanks

That link is to a socket, as I said before DO NOT FIT A SOCKET, that will be lethally dangerous.

 

[David Prosser]

Ha, Thanks davesparks. I did mean a inlet plug. such as this link..

Industrial Socket IP67

• IP20

www.toolstation.com

I thought the isolator main switch type must have a -off- position, however doesn't say it in any of the product descriptions. I will call up my supplier after easter and confirm it.

Thanks

FFS mate, you could really end up killing someone if you fit that, you need a machine inlet plug like this.

248.3293 | Scame IP67 Blue Panel Mount 2P + E Industrial Power Plug, Rated At 32A, 230 V | RS

uk.rs-online.com

 

[Scott1978]

That link is to a socket, as I said before DO NOT FIT A SOCKET, that will be lethally dangerous.

Sorry. Now I get what your saying.

This should me more suitable.

FFS mate, you could really end up killing someone if you fit that, you need a machine inlet plug like this.

248.3293 | Scame IP67 Blue Panel Mount 2P + E Industrial Power Plug, Rated At 32A, 230 V | RS

uk.rs-online.com

This one ok ....

230V 16A 3 Pin MK Commando Surface Appliance Inlet - Blue - IP44 | MK (K9701BLU)