Heger SFT changeover switch anyone?

Has anyone used a Heger SFT DP changeover switching fitted directly on the DIN rail in the consumer unit rather than using a separate changeover switch enclosure for installing a portable generating set in a fixed (domestic) installation? I am trying to find a solution for limited space in the DB cupboard?

My current thinking is the petrol generator hooking up to an external wall mounted 16A appliance inlet, feeding directly onto the Heger changeover switch before an RCD and several circuits within the CU.

I'm wondering in this unit can serve as both a manual changeover, plus DP isolator (in the central position). If it's suitable rated is there any reason why I can't do this and avoid an extra enclosure??

ta

I'd say you probably can as long as you configure it correctly .    As long as you don't get a back feed when the mains are reinstated  and you're not pumping 240V  down the mains  during the power cut .

You will have trouble with the busbar. It's finger will be expecting to enter the middle of the "contact position"  But because that has 4 cables into the bottom, that termination will be offset slightly. And the terminal is probably smaller so will the busbar finger even fit.

Can you shuffle all the gear to the left by 2 modules and fit this changeover as well as the normal main switch?  That I think would be acceptable.

Will that Hager switch not struggle as it is only rated at 40 A. Not sure how it is configured, will it be one side going to consumer unit then either select grid supply on genny? if so when it is on grid the 40A rating may be an issue.

providing I can configure the circuits linked to the changeover-RCD busbar to below 40A I should be okay shouldn't I? 

The customer has two 12 way CUs alongside one another, each with 7 circuits and three spares. The first CU also has the main switch and non-RCD protected circuits. The second CU is fitted with an RCD. If I can rearrange the circuits so the second CU is drawing <40A (which is way above what the generator can provide) I should be okay?

Any circuits I remove from the RCD protected CU I will replace the MCB with RCBO. 

Am I just making a whole lot of work for myself? I've noticed there aren't many wholesaler that stock the din rail 40A changeover, although Google does suggest they are more popular in Australia for some reason. Is this just down to awareness and familiarity, or are there reg concerns??? I acknowledge introducing two potential sources increases the risk, but we have labels etc to manage that....?

I'm sure I'm missing something as this solution does away with one of those ugly changeover switch boxes and if it were that obvious everyone would be doing it.

Your property or a customers ?

customers

I've nothing to hide. This is the draft plan I am working on. I'll use it as the basis on my quote, method statement and installation certificate.

You guys seems helpful, so I'd welcome your thoughts..... 

View attachment draft.pdf

wow... so much wrong with that plan, easier to start again, properly this time....

your generator may be limited in power, but mains supply coming in isnt. the chage over device would therefore need to be suitably rated for the highest current. they do exist in higher ratings

moving non essential to RCBO's on the other board would work, but how do you plan on dividing them up? (at a guess, just moving certain circuit, such as upstairs sockets and leaving downstairs etc?)

why do you need 16mm cable to your 16a inlet? even if you plan on going upto 40a, the max of your changeover switch, 16mm is probably still overkill and might not fit into the termianls.

the big major thing in that is you have 'wall mounted socket' which you intend to use for your inlet. you need a wall mounted inlet, not socket. if you were planning to use a socket, then quit electrics now, and the lead you need to connect it is more commonly known as a widow makrer for somewhat obvious reasons

fitting a N-E link in the plug to give an earth is not suitable. its also possible that will will do damage and go bang as some generator outputs are CTE, linking N-E will effectively short circuit it

you will need earth electrode(s), however this will not give you a good Zs, thats to provide an earth path back to the generator, not to earth the installation.

SWA is not designed to be used as a flex connected into 16a plugs / sockets. you need a suitable cable

Personally I think you’re opening yourself a can of worms, juggling circuits (8 off i note - less than 40A?) how to do you propose to split them? 
for what are the sockets for? Please not a link to generator? Death by wrongful touch springs to mind? 
what’s with linking NE in socket? Not permissible. 
 

to name just a few reasons I wouldn’t proceed with this plan??? 

- Your right about the 17A socket. I spotted that typo and forgotten to update it. No need for the snark though, I’m after constructive feedback!
thanks for your advice everyone. 
- the neutral earth link would be made in the cable only as advised (I believe) on the NICEIC tech pages, so neither the install or generator are adapted. 
the 16mm cable was simply because I had the SWA to hand to put through the wall from wall plug to changeover. 
there are so many circuits because it is an old property. Many of them are 6A lighting circuits. 
if I’m starting again, do you have any advice as it is my first time coming across this request. 
 

thank you

D

What are your thought on the Heger changeover din switches? The larger ampage unit takes four spaces. 
i was thinking of the top CU taking a feed straight from the main Switch, as you would an RCD, then running that route into the RCD, bus at etc. 
 

Can I ask what was the reasoning behind this request? Only a small petrol generator is not designed to be run continuously and the output is somewhat limiting? 
If the customer is adamant that they need a back up generator then I’d be more inclined to design a suitable sized generator and circuit arrangement for a permanent offering? 

I think you are giving too many details of the parts you intend to use (picky customers will add up the prices and demand discount or more of a breakdown)

You haven't stated a maximum design load for the generator / circuits split off so in theory your generator won't have enough output to cope

Maybe decline this one

Thank you, very useful feedback. 
I suspected what I was proposing was untypical as the parts were not as easily available. I’ll feed back that it would be unwise to link an underpowered generator to a variety of loads, potentially for hours on end. 
I’ve had similar feedback from a colleague  that I was offering too much detail, but it was intended as a template for the inspector/certificates. I would pare this down for general circulation. It is still being edited (hence the original question and feedback request)

When you say inspector, is that for a scheme assessment? 

I’m not CPS yet, so want the plan approved by building control before commencing. I’d dread to think what feedback I would have received if I’d given them this!

Ouch! You really pick your assessment projects! 

It’s all been going so well until now!!!