Non protected circuits

[whistler]

Electrician fitted a new consumer unit for me. I had asked for 10 way as I needed 8, but thought a couple of spare ones may be useful in the future. The unit he fitted is a Wylex NHRS 10SSLH1 and is configured with two five way sections independently rcd protected. The remaining two are unprotected. One is blanked and one has an unused mcb.

First question. Why are two circuits unprotected? What would you connect to these ?

Second question. If I needed to use these in the future would they need RCBOs installed?

Third question. Can the rcbs be shuffled along to give protection over all 10 ways?

 

[EFLImpudence]

Why are two circuits unprotected? What would you connect to these ?

How do you know this?
There are no circuits there at the moment.

If I needed to use these in the future would they need RCBOs installed?

Not necessarily.
If you want.

Can the rcbs be shuffled along to give protection over all 10 ways?

The CU can be configured how ever you want.


I think your lack of understanding is causing confusion and unnecessary worrying.

 

[whistler]

I sometimes wonder why I bother asking questions on this forum when you get answers like that.

 

[sparkwright]

Yes, it was a bit harsh.

The remaining two 'unprotected' ways are so you can add circuits not protected by the two RCDs.

For instance, you may have a circuit you don't want to lose if one of the RCDs failed.

For example, you may have an outdoor circuit like garden lighting or a shed, which is likely to trip in the case of moisture. It would be annoying if half the house lost it's power too.

On one of these unprotected ways you could have an MCB or RCBO.

An MCB alone doesn't offer any RCD protection, but under certain circumstances not all circuits require it.

Most circuits do require RCD protection now, so you would use an RCBO. An RCBO is a cross between an MCB and an RCD.

Ideally a consumer unit shouldn't have the two RCDs you have, just RCBOs instead of MCBs.

However, RCBOs are expensive, so one would be reluctant to buy a lot of these, so a dual RCD board such as yours is a cheaper way of doing it.

Many wholesalers do your type of board at a discount, it's likely yours was a good deal.

Not that you would necessarily been told that.

Though you would have to pay a little more for an RCBO than an MCB would cost to add a new circuit, it's good to know you have the option of putting a particular circuit on it's very own RCD, so if a less important circuit should be faulty, the important one will remain working.

It's very likely the board can be shuffled about so the two RCDs can cover all the ways, though you may need new busbars.

 

[EFLImpudence]

Yes, it was a bit harsh.

Factual, nonetheless.

The remaining two 'unprotected' ways are so you can add circuits not protected by the two RCDs.

We don't know that, the busbar may extend to these two ways.
That's why I asked "How do you know this?"

For instance, you may have a circuit you don't want to lose if one of the RCDs failed.
For example, you may have an outdoor circuit like garden lighting or a shed, which is likely to trip in the case of moisture. It would be annoying if half the house lost it's power too.
On one of these unprotected ways you could have an MCB or RCBO.
An MCB alone doesn't offer any RCD protection, but under certain circumstances not all circuits require it.
Most circuits do require RCD protection now, so you would use an RCBO. An RCBO is a cross between an MCB and an RCD.
Ideally a consumer unit shouldn't have the two RCDs you have, just RCBOs instead of MCBs.
However, RCBOs are expensive, so one would be reluctant to buy a lot of these, so a dual RCD board such as yours is a cheaper way of doing it.
Many wholesalers do your type of board at a discount, it's likely yours was a good deal.
Not that you would necessarily been told that.
Though you would have to pay a little more for an RCBO than an MCB would cost to add a new circuit, it's good to know you have the option of putting a particular circuit on it's very own RCD, so if a less important circuit should be faulty, the important one will remain working.
It's very likely the board can be shuffled about so the two RCDs can cover all the ways, though you may need new busbars.

Hence - "The CU can be configured how ever you want."