Hybrid circuits

[Pete999]

Morning all, been pondering quite a bit lately about Hybrid circuits,especially 13amp socket circuits, the likes of lolly pop rings etc.

I don't want to get into arguments about the pros and cons and why people install them, that's been done to death, whether, I personally agree with this method is neither here nor there, no, my question is, " how are these circuits tested, and how are the results entered on the installation certificate?" for example if you have installed a lolly pop ring how is that described? as a ring or a radial.

 

[7029 dave]

I was just using a the analogy of a db supplying more than 1 final cct as opposed to a switch supplying the lollipop head in the middle of a final cct.

A spider/octopus circuit is just a radial with multiple spurs from the same point so just a pain for testing.

I can't get my head round a 'spider ring'. Sounds like a lollipop with a figure of eight ring to me, which surely can't be compliant.

Spider ring??

Pretty common on lighting circuits in days gone by. (joint box system)

 

[Deleted member 26818]

Unfortunately not all spider circuits are radials, the ones I've come across whilst doing EICRs are usually rings.
Look in the board, 2 cables on a 30/32A OCPD, assume it's a ring.
Drop one of the socket fronts, one cable, must be a spur.
Drop all socket fronts, they're all spurs.
Can't lift up carpets, can only check for conductor continuity and Zs at each socket.
In one case the ring spider covered two floors.
Can't spur off of any of the sockets, not even back to back.
Could remove one of the sockets, replace with an FCU then feed two or more sockets from the FCU, but it's a pain if the socket is a double.

 

[Leesparkykent]

Totally called for and perfectly true.

oh I didn't realise sorry

 

[andyelectric]

Unfortunately not all spider circuits are radials, the ones I've come across whilst doing EICRs are usually rings.
Look in the board, 2 cables on a 30/32A OCPD, assume it's a ring.
Drop one of the socket fronts, one cable, must be a spur.
Drop all socket fronts, they're all spurs.
Can't lift up carpets, can only check for conductor continuity and Zs at each socket.
In one case the ring spider covered two floors.
Can't spur off of any of the sockets, not even back to back.
Could remove one of the sockets, replace with an FCU then feed two or more sockets from the FCU, but it's a pain if the socket is a double.

Sorry. Don't get you. I may be being thick but your 'spider ring' just sounds like a ring withs spurs. Sorry if I don't quite get it.

 

[ipf]

Yes it can be used for volt drop reasons.

But a switch cannot be used in place of a DB! And I don't see why you would want to put a DB in the middle of a final circuit????

In a commercial kitchen the wiring was installed, including a section of a rfc to an island incorporating socket outlets. The stainless steel island arrived on site with a built in db. What's wrong with incuding the supply to the db in the ring?....that's what I did. When we're talking hybrids, we're talking adaptation.

 

[davesparks]

A spider ring is a ring which runs round the building with a JB and spur for every point.
The ring doesn't run to any sockets, it just literally forms a loop which every socket is spurred from.

 

[davesparks]

In a commercial kitchen the wiring was installed, including a section of a rfc to an island incorporating socket outlets. The stainless steel island arrived on site with a built in db. What's wrong with incuding the supply to the db in the ring?....that's what I did. When we're talking hybrids, we're talking adaptation.

Nothing wrong if calculations and loading a all check out ok

The guy was suggesting a DB in the middle of a final circuit with no apparent reason for it

 

[Deleted member 26818]

Sorry. Don't get you. I may be being thick but your 'spider ring' just sounds like a ring withs spurs. Sorry if I don't quite get it.

Yes that's exactly what it is.
As such you cannot spur from any of the sockets, as they are already spurs.
You cannot without lifting carpets and floorboards check the terminations or joints, and I'm not sure they saved any cable or money compared to a normal RFC.

 

[Knobhead]

The original “Octopus” system

Now you would use an adaptable box with DIN rail connectors. It still has its uses as I found out many years ago.

Spider web is several radials from a central point with interconnects between various points of the radials. I’ve only ever known it to be used on 11KV systems. The protection is a nightmare.

 

[ipf]

Nothing wrong if calculations and loading a all check out ok

The guy was suggesting a DB in the middle of a final circuit with no apparent reason for it

Not having a go...just another example of how designing a circuit isn't necessarily shown in the picture book..:icon12:

 

[Guest55]

The original “Octopus” system

.

are those lead sheathed twin flats ?

im guessing that kits circa early fifties........

 

[7029 dave]

Looks like twin rubber to me.

 

[davesparks]

Looks like TRS to me

 

[Deleted member 26818]

Looks like the Reds and the blacks are connected together.

 

[ipf]

are those lead sheathed twin flats ?

im guessing that kits circa early fifties........

Look like rubber/pvc to me...if it's lead, its prior to that.....now that's what I'd call a 'loop in' box....