Generator connection to house

[jimAuk]

Hi All

Just after some guidance so I am a bit more clued up about what I am talking about when I get my local Electrician round for a quote for the following work.

This is the diesel generator I have

http://www.pramac.com/United-Kingdom/en/soundproof-open-set-generator-p-6000s-1314.asp

used for back-up power via running a single extension lead to the house for a lamp or kettle boiling, but really at 6kw it could be used for a bit more! /?

SO I am thinking a manual changeover switch.

Given that the max 240V I have of this is 16A it is not like I could run the electric cooker or electric induction hob, or that I would want to.

I suspect mainly just lights and maybe the oil fired boiler/it pump, does this sound feasible?

From our meter tails, we have two main consumer units, one for sockets etc and the other for lighting, so one thought rather than powering all would be only to power the lighting section, but if we when into the main incoming and though our own intervention did not turn on high load appliances, this would give us power to sockets and mainly the boiler etc.

As for the switch I have see this one

http://cgi.ebay.co.uk/125-Amp-Gener...ls_Supplies_Electrical_ET?hash=item45f037ebda

Would I need 125Amps? Do I need 2 or 3 pole?

Don’t worry as stated above I am NOT doing this work myself, just wanting some independent thoughts to put to my electrician ( I know it is part P “Special location/installation”)

Thanks

 

[Spark123]

If you place a changeover switch in the meter tails then you will need the correct size for normal service i.e. when your system is on mains.
If you have a 100A service then you need at least a 100A change over switch.
As you are dealing with single phase a 2 pole change over switch is adequate, the one you link to in the pic is a 2 pole one.
Also ask your electrician regarding the earthing type, smallish generators often provide a floating supply so might need a link put in. Your electricity supplier might not like you using their earth hence it might mean driving an earth electrode in and using that, that is really up to your electrician to sort out.

 

[nozspark]

Does that change over switch comply???

I thought that it had to be a SUPPLY 1 -- OFF -- SUPPLY 2 type?

That one doesn't seem to have that configuration??

 

[jimAuk]

Possibley not!

I think this style is better anyway way

http://www.genpoweruk.co.uk/product.php?productid=16157

 

[Spark123]

You mean break before make?
It is being sold as for the purpose of being a generator changeover switch so I'd take it that is what it is.
I don't really rate CGD stuff tho, it is budget stuff.

 

[jimAuk]

I think the changeover switch in the meter tails will be the best option., so power to all of the house, even if the likes of the cooker will be off limits to the generator.

As you state yes we have 100A supply on mains, so even if gen is not 100 A, you still need the 100A + rated unit to switch the mains.

If I do that route, do people see a problem with the size of generator I am using? what sensibly can I run with it?

I can get the generator upgraded to a 32A 240v socket, or is 16A Ok for this back-up usage?

Can anyone recommend a 100Amp + switch?

I have emailed the ebay seller asking if it is make before break as you have rightly spotted it does not appear to have a mid point of "off" like the Moeller ones.

Thanks

 

[nozspark]

Looking at the other pictures in the link it only looks like a 2 position switch, which to me is non-compliant.

I like the type that Jim linked too, the ones I've used are Katko ones.

 

[nozspark]

The best way to do this would be to have your essential services fed from a seperate CU.. In the feed to this CU fit a changeover switch,, the only problem could be your earthing(???)

Ideally, and if your genny is up to it? you could have the lighting, boiler, fridge / freezer and maybe a socket for your TV

 

[jimAuk]

Just seen the katto ones £300 + !

http://katko.co.uk/pages/pricelistclosed.html#kem3160vv102

I looking at £150 tops for the switch! + cost for sparky

 

[jimAuk]

If we just had it set up that it could feed everything, but we did not turn the high loads on, is that OK/Legal ?

So considering the intended use (back-up) yes the whole house is in effect live but all that will be drawing will be a few lights, fridge/freezer and boiler if that time of year, for the period of the out-age.

Rather than running addtional CU's and the associated cost.

 

[nozspark]

I think that you must be looking at the wrong switch??

Your genny is rated at 21.5A COP (IIRC)?

Katko only do 3 & 4 pole change over switches and the smallest one is more than suitable for what you need (40A)..
Here's a linkhttp://www.katko.co.uk/products/enclosed/polycarb.html#changeover
and the list price is £86.41 +VAT.... can't remember their delivery charges but IIRC I got a small discount (being an electrician)[/url]

 

[nozspark]

If we just had it set up that it could feed everything, but we did not turn the high loads on, is that OK/Legal ?

So considering the intended use (back-up) yes the whole house is in effect live but all that will be drawing will be a few lights, fridge/freezer and boiler if that time of year, for the period of the out-age.

Rather than running addtional CU's and the associated cost.

If it was me fitting it, then no..

because you (or someone else in the house) could forget that you are running on genny and try and have a shower or put the oven on.

I know that you will say that you'd turn the breakers off to those items, but what if you forgot??

 

[mfarrow]

nozspark, he needs a switch rated at the maximum of the two (DNO and genny) so 100A minimum.

Also I would install the genny as a TT with RCD and not rely on the DNO's earth during an outage, which IMHO is a very dangerous thing to do - what if they cut the cable completely outside your house with the generator running and you get a fault?!

 

[jimAuk]

Your genny is rated at 21.5A COP (IIRC)?

But I thought the switch had to be rated to largest load it would switch i.e the mains so need to be 100A + (125A)?

You are right about the "human error factor" and the fogetting on genny and OH switches oven on.

As I said above, from the tails we have 2 CU's allready one is sockets etc and other is manly lighting, so possibley not to much of a swap around to get generated CU circuits.

But surley I would still need a swich to break before making on the generator, so still need it at 125 Amps?

 

[jimAuk]

nozspark, he needs a switch rated at the maximum of the two (DNO and genny) so 100A minimum.

Thats would I thought!

Also I would install the genny as a TT with RCD and not rely on the DNO's earth during an outage, which IMHO is a very dangerous thing to do - what if they cut the cable completely outside your house with the generator running and you get a fault?!

Yes I thinks so, so in effect it is a complety seperate system.

Please clarify TT?

And DNO which I assume is somthing to do with the power company?

Thanks mfarrow