Main incoming cable 10mm

[westie101]

You need a point of isolation and protection (fuse, circuit breaker) at the supply end of the cable.
You will also need an RCD which, I think, can be at either end

 

[RF Lighting]

Oh right, no you need to terminate the SWA direct to your CU at the remote end, and direct to the switch fuse or CU at the house end.

As westie has mentioned, you need a point of isolation at the house end, and your own OCPD. You can't rely on the DNOs OCPD to protect your cable.

The RCD can go at either end, but is best at the remote end.

What difference does it make to you if your electrician is installing this? He'll be used to working with the cable. 25mm² 3 core SWA isn't particularly difficult to work with.

 

[ban-all-sheds]

For BAS! The complaints from customers in a similar set up where one was using a 13A plug in welder and playing havoc with their supplies!

Mines a bit more than 13A. Not a lot, but a bit, at least some of the time. 13A BS 1362 won't quite hack it. I'm a bit ashamed of what I did about that [DEFENCE] I was a callow youth [/DEFENCE], but I don't use the welder any more. Don't want to part with it though, so at some point I'll put a 16A 60309 on it.

My Dad used to have a saw with a split-phase induction motor which took somewhere approaching 10s to get up to speed, and whenever he started it up the house lights would dim and slowly return to full brightness and the TV picture would shrink and then slowly expand.

Never got any complaints from the neighbours - they were all too busy gnashing their teeth about the noise from the RF gluing machines in the furniture factory well over a mile away which cut through 405-line TV and AM radio signals like a plasma torch through gold leaf.

 

[westie101]

BAS
I think the best one I had as the farmer with a huge 25A input machine that kept complaining about his own lights dipping when he used it!
He just would not understand that: -
it was his own fault
he needed our permission to use it.

In the end, as he was not affecting anyone else, we fitted a voltage regulator to his supply (it was a long single phase cable) and left him to it!!

Many years ago when I was training and in the planning section we got an application for a huge amount of spot welders for a heating radiator manufacturer. With the size, number and frequency of use of the machines it needed 2 parallel 11kV cables to the site from the nearest 33/11 substation, a distance of about a mile.
For welding plant the highest voltage drop we can permit is 1% owing to the frequency of the dips.

Just to expand on that, the permissible voltage dip is at the point of common connection, i.e. where it would affect other customers.
For welders and frequent (more than once per hour, I think) start motors it is 1%
For infrequent (less than once per hour, I think) start motors it is 3%

It is all to reduce interference with other customer's supply, we don't mind what it does to yours!!

 

[ban-all-sheds]

Not sure that DIY use of a small (until you try to lift the b****y thing) welder counts as "plant".

 

[westie101]

Not sure that DIY use of a small (until you try to lift the b****y thing) welder counts as "plant".

I doubt it does, but the 1% limit still applies

 

[ban-all-sheds]

I look forward to reading the notifications about all of this on the welders they sell in the sheds.

Not that I'm in the market for one, but it does raise an interesting point in line with John's earlier comments. These are things which you can just buy and plug in - how on earth is anybody supposed to know that they need to get DNO approval before they use them?

 

[westie101]

End of the day experts stress and stress again to read the small print before buying or doing anything!

If folk take a supply of electricity it is up to them or their advisers to understand the T&C's. As for stuff sold in sheds etc. as with many things it is not illegal to sell them just to connect and use them.
How many have advisories on wiring accessories relating to Part P, it is no different!

 

[JohnW2]

Not that I'm in the market for one, but it does raise an interesting point in line with John's earlier comments. These are things which you can just buy and plug in - how on earth is anybody supposed to know that they need to get DNO approval before they use them?

Indeed. In fact, the 'DNO approval' thing can be totally undermined by even 'everyday' plug-in items. Although most of them are very rarely used, I must have at least a dozen 2kW fan heaters in my house, and more than enough final circuit capacity to support them. Were I to decide to switch them all on (e.g. if other heating systems failed), that would be a very substantial, although not 'fixed', load - am I meant to tell my DNO that I have all those fan heaters and ask their permission to switch them on?

Kind Regards, John

 

[SaladFingers]

In the grand scheme of things, a leccy shower uses more, not portable but stilll uses more current!

 

[JohnW2]

In the grand scheme of things, a leccy shower uses more, not portable but stilll uses more current!

[if this is a response to my latest post] ... certainly not more than (or even anything like as much as) my 24kW+ of portable fan heaters. In any event, even if it did, a shower is never going to be used for hours on end, in the way the heaters might well be.

Kind Regards, John

 

[Lectrician]

So ask the DNO and find out!!
It will vary upon location but generally we would advise any load over 3kW, any off-peak heating, any fixed motor above 1hp single phase and any welder of any size!

My DNO would have a laugh at me if I approached them - "i am fitting a new 3kw plinth heater, can you amend my connection and charge statement please".

What about a new kitchen with a dishwasher, or these days an instantaneous tap etc? How many new kitchens go in without a thought to the increase in loading?

 

[bernardgreen]

End of the day experts stress and stress again to read the small print before buying or doing anything!

Sadly very few do read terms and conditions. ( I think some cannot read them )

As for stuff sold in sheds etc. as with many things it is not illegal to sell them just to connect and use them.

This is where there could be an improvement. Make it a requirement that advisory information is printed on the packaging where it cannot be missed.

And maybe on the electricity bills a reminder. If the modern electronic meters can record peak current levels then if ( when ) there is a prolonged usage at or above the contracted supply maximum the meter could inform the billing department who then add the caution to the bill. "your consumption exceeded agreed maximum supply, please seek advice".

 

[bernardgreen]

My DNO would have a laugh at me if I approached them - "i am fitting a new 3kw plinth heater, can you amend my connection and charge statement please"

When I applied for a new supply connection I had to list all fixed appliances above 1 kW that might be installed at some point in the future.

How many new kitchens go in without a thought to the increase in loading?

Too many, and when things do go wrong ( supply voltage drop etc ) the installers terms and conditions absolve the kitchen company from blame. The case I am thinking of was an electric range cooker replacing an LPG at the end of a rural line. Voltage drop resulted in compliants and replacing the range cooker with a LPG one was the cheapest option. The kitchen company ( or cooker supplier ) made it clear ( in very small print ) it was the client's responsibility to contact the electrical supplier to verify the local network supply was adequate for the range cooker.

 

[Chri5]

What will you be doing in the outbuilding?

I take it you intend to fit a switch fuse and run off that?

OP are you now clear regarding the job?

Main supply tails in 25mm sq to Henley, tails to existing cu, tails to switch fuse (80 amp), swa connected to switch fuse, run to outbuilding, cu with RCD or Cu with bank of RCBOs.

The switch fuse is a requirement for an connection beyond 3m frm main supply, so you may need one for main house cu if the distance is great than 3m.

I'd take the swa to the switch fuse direct, I hate the idea of an internal unprotected cable with a potential 80 amp capacity between switch fuse and swa junction. Imagine putting a nail through it