Multiple Cables in a single circuit breaker

[Kris_88]

Hi all, advise needed please (Commercial)

Before I go into detail about why I ask, as this may be a silly question with an easy answer, is there any regulation or reason why two circuits cannot be fed from one circuit breaker providing all cables connected are adequately protected by the device and all loading has been considered?

For example a 10A circuit breaker feeding two circuits, both doing a small amount of lighting in a commercial premises, where it could have easily been wired as one circuit when looking at the load and coverage?

 

[ImpededLoop]

No reason at all. It's no different to there being a joint box near the origin of the circuit with two outgoing cables.

 

[LeeH]

It will only be 1 circuit, not 2. You'll just have more points served.

 

[Darkwood]

Yes ... if it impairs the termination of the mcb other than that NO!... Ive seen several coming out of an mcb before and although it gripped some tightly others were loose.

 

[Plonker 3]

Absolutely nothing wrong with it as long as you comply with the BGB

 

[Lucien Nunes]

You could rephrase the question as "Is there anything wrong with feeding a circuit in the middle instead of at one end?"

Just note that there are two 'last' points at which to carry out tests.

 

[Kris_88]

Thanks for the response guys. Personally I haven't done this before, not because I've felt there's anything wrong with it but from a testing perspective I feel it's easier to have the daisy chain with one end point rather than multiple end points.

On the job I'm currently on it would make sense to do this for a particular circuit so thought I'd run it by you all.

Thanks Again All!

 

[rich.250]

You could rephrase the question as "Is there anything wrong with feeding a circuit in the middle instead of at one end?"

Just note that there are two 'last' points at which to carry out tests.

Shouldn't you be testing all points anyway...

 

[Engineer54]

If you think about it, it's just not possible to have two or more circuits being supplied from a single OCPD.

 

[LeeH]

Shouldn't you be testing all points anyway...

Inspect maybe, test at every point, no.

I test from the furthest point or points.

 

[Kris_88]

Ok, for anyone who hasn't noticed from the rest of the thread above, I've used the word circuits but actually just mean a set of conductors. I wrote it this way to try and express that in some cases I've seen there may be one twin & earth feeding an insect killer, and another feeding a couple fridges. If for instance the neutral went down on the leg feeding fridges, it would no longer be a circuit as there wouldn't any current flow but this would have no effect on the fly killer leg of the circuit unless it caused a fault that activates the device, hence why I considered it two different circuits grouped together.

I accept that it may have been the wrong way to describe the question, but in this case I just wanted to know if it's ok, not if it's the right way to phrase it.

 

[rich.250]

Inspect maybe, test at every point, no.

I test from the furthest point or points.

I test from every point, wether it's an R2 of a class one fitting or an R1+R2.
You need to verify the earth at every fitting or fixture. Especially if it's not class 2. You could have an earth at your furthest point but not attached somewhere in between and just jointed through!!

 

[LeeH]

You can visually inspect for that.

I don't do much testing tbh in this area but when I have getting the meter out at every point would have been time consuming and unnecessary IMHO. But we all have our ways I guess.

 

[Darkwood]

Ok, for anyone who hasn't noticed from the rest of the thread above, I've used the word circuits but actually just mean a set of conductors. I wrote it this way to try and express that in some cases I've seen there may be one twin & earth feeding an insect killer, and another feeding a couple fridges. If for instance the neutral went down on the leg feeding fridges, it would no longer be a circuit as there wouldn't any current flow but this would have no effect on the fly killer leg of the circuit unless it caused a fault that activates the device, hence why I considered it two different circuits grouped together.

I accept that it may have been the wrong way to describe the question, but in this case I just wanted to know if it's ok, not if it's the right way to phrase it.

Try not to get your back up here, you were corrected on a minor point but at the end of the day using the correct terminology and phrasing is the sign of good education and understanding, you would be surprised how a minor error in terminology can be costly if written in a job spec', although not really in your case but consider how many members we have on here that question about garages etc then ask if they can export the PME/TNCS instead of using the term 'extending the equipotential zone' - totally different things.
When you work along side Electrical Clark of Works and/or Electrical designers etc then using incorrect terminology can make you look incompetent and in some cases may lose you work if your quoting for a contract as such.

All I'm saying is, try not to throw your toys out of the pram because you were corrected, this is one of the benefits of the forum and helps refine your knowledge although I will agree there are 2 ways to correct someone and we do have members that circle like vultures and come in like its there first meal in months.

 

[Pete999]

Try not to get your back up here, you were corrected on a minor point but at the end of the day using the correct terminology and phrasing is the sign of good education and understanding, you would be surprised how a minor error in terminology can be costly if written in a job spec', although not really in your case but consider how many members we have on here that question about garages etc then ask if they can export the PME/TNCS instead of using the term 'extending the equipotential zone' - totally different things.
When you work along side Electrical Clark of Works and/or Electrical designers etc then using incorrect terminology can make you look incompetent and in some cases may lose you work if your quoting for a contract as such.

All I'm saying is, try not to throw your toys out of the pram because you were corrected, this is one of the benefits of the forum and helps refine your knowledge although I will agree there are 2 ways to correct someone and we do have members that circle like vultures and come in like its there first meal in months.

Come on darkwood get yer terminology right that should read Clerk of Works LOL:angel_smile: