Property: 3 flats to one house

[Dambo]

I've been to seen a customer this evening who has a property which is divided into 3 flats, each with it's own fuse board and electricity meter. He wants to convert the property into one single house obviously then running off one meter.

He wants each floor to still have its own fuse board (to bring the price of the work down). I've advised him to update each fuse board to 17th edition then with each board being RCD protected but whether or not he does this, in his words, is again dependant on the price.

Just out of curiosity - If the fuse board on each floor were to remain the same, could they all be protected by one 100a main RCD next to the meter?

 

[Andy™]

you should avoid everything on one RCD. in this case, it would be fairly easy - stick an RCD on the feed to each board. either next to DB, or on tails next to meter. may also need switch fuses for tails though.

only concern would be 3 flats, large area, possibly too much for 1 service head/meter (depends on expected use)

 

[Dambo]

[quote name='Andy

 

[sparkytim]

If customer is billed just for Units used with no standing charge, then no need to alter Metering arrangements, just gets 3 bills instead of 1

 

[Apache]

If customer is billed just for Units used with no standing charge, then no need to alter Metering arrangements, just gets 3 bills instead of 1

I pay more for first X amount I use then less after that, basically a hidden standing charge.

 

[Dambo]

If customer is billed just for Units used with no standing charge, then no need to alter Metering arrangements, just gets 3 bills instead of 1

He wants everything to be on the one bill. What's the purpose of switch fuses when each DB would have an RCD main switch?

 

[m4tty]

think it's for protecting the tails as they will be over 3 metres long but stand to be corrected mate

 

[Lurch]

What's the purpose of switch fuses when each DB would have an RCD main switch?

As above, you can;t just arbitrarily stick cables into meters regardless of size or length.

 

[Dambo]

think it's for protecting the tails as they will be over 3 metres long but stand to be corrected mate

How will a switch fuse protect the tails?

As above, you can;t just arbitrarily stick cables into meters regardless of size or length.

I've no intention of just sticking any cables into meters. All I want to know is why a switch fuse is needed?

 

[Lurch]

So just to clarify, you're asking how a fuse protects a cable?

 

[Dambo]

So just to clarify, you're asking how a fuse protects a cable?

I'm asking why an RCD main switch protecting each DB isn't sufficient?

 

[Lurch]

I'm asking why an RCD main switch protecting each DB isn't sufficient?

Lack of overload protection?

I do think you have overstretched yourself with setting up on your own, you do sometimes seem to not comprehend some of the basics.

 

[Andy™]

How will a switch fuse protect the tails?

headbang

 

[Dambo]

Lack of overload protection?I do think you have overstretched yourself with setting up on your own, you do sometimes seem to not comprehend some of the basics.

In a normal domestic dwelling the tails from the main fuse feed into the main switch in the DB via the electricity meter. In this instance the tails from the main fuse will lead into the main switch in the DBs via an electricity meter. If a switch fuse isn't needed in a normal domestic dwelling why is it needed here?

 

[Andy™]

all cables must be protected for overload/fault current. there is an exemption that you can use DNO fuse to protect tails, but upto 3mtr (sometimes less depending on DNO ). any longer, and you must provide a switch fuse

 

[Dambo]

[quote name='Andy

 

[Lurch]

In a normal domestic dwelling the tails from the main fuse feed into the main switch in the DB via the electricity meter. In this instance the tails from the main fuse will lead into the main switch in the DBs via an electricity meter. If a switch fuse isn't needed in a normal domestic dwelling why is it needed here?

As has been said several times in this thread, you need to protect the cables in the installation. The DNO's provide guidelines on what you can do with tails, and downsizing them\running them across the house (usually classed as anything over 3m) isn;t something you can do.

This isn;t some secret piece of info that only elite electricians learn, it is mentioned in the OSG (I think, sure it's mentioned somewhere prominent in a popular document). Also, common sense should tell you that the 100A fuse will be fine protecting a 2m piece of 25mm 6181Y but not a 20m piece of 16m 6242Y.

What name do you trade under?

 

[Lurch]

Ah, I see. So is it best to put the switch fuse next to the DB or next to the electricity meter?

I rest my case.

 

[Andy™]

Ah, I see. So is it best to put the switch fuse next to the DB or next to the electricity meter?

headbang :red card

 

[sparkytim]

Hi Damien

Are all the Consumer Units and Existing Meters in the same location?

If they are then NO switch fuses are required if all tails are less then 3 mtrs, they can all come from a double pole Henley type block off one set of tails from One Meter.

If however each Consumer Unit is at a remote location then the Distribution circuit must be provided with Over current protection, RCDs do not protect cables from overload or short circuit type faults.