2nd Circuit - A&B CB Breakers Question

[Chao Lao Beach]

What is the difference between A16 and B16 circuit breakers, same brand ?

Now the 2nd question:

I am installing a second indipendant circuit into a tempory place, it is a shortish term rental, but the land load doesn't care what I do, (actually he seems to do nothng!

The line from the street comes into the box which is in the center of the house, it is mounted on a wall and the cable go though the ceiling and down internally within the wall, first going into a seperate RCCB then into the CB box.

The 2nd indimeand circuit will be 2.5mm to its own box with RCCB, my question is, how to best join it Thai style.

1. Jam the new 2.5mm into the top of the saftey switch and join there ?

2. strip some insularion off ion the ceiling, join and wrap, the Thai sparky want to do this.

Q, do I need a break near the join, or is just at he box ok, it will be a 12m run.

[Crossy]

Basically the difference between breakers type B, C and D is the level of overload required for an 'instantaneous' trip. Most sparkies (and electrical emporia) seem to provide C curve breakers as a happy medium.

Timing curves here:-

As to connecting it up. The preferable solution is to insert the 2.5 alongside the incoming supply as the breaker box. It's not ideal as you won't have a single point of isolation, but at least you can see the cable so you know something is connected (unlike doing it in the roof).

Remember this will need to be done live, so get sparky to do it

The breaker needs to be as close to the t-off point as possible, remember that bit of 2.5 has no protection until you get to the breaker, even the Thai supply will have no problem at all vaporising it.

[Forkinhades]

You cannot get 'A' type. Not seen many 'B' type here also. Mostly 'C' type.

The difference is how much inrush current they can withstand. Typically a 'B' will be 5 times nominal current (5 × 16). 'C' will be 10 times.

If you have a fuse box already installed, just put the new supply on a spare way. Or you could double up on existing fuse way.

[Crossy]

Forky, something not apparent from our OP is that he wants a non-RCD protected outlet for some sensitive equipment so he wants to take the supply from the incoming side of his Safe-T-Cut.

[Forkinhades]

^?? Second circuit to be protected by RCCB

If so, just use existing safety- cut

[Crossy]

^?? Second circuit to be protected by RCCB

If so, just use existing safety- cut

Indeed it does, not what he said in his PM to me (Safe-T-Cut trips occasionally leaving his kit without power and needing to be reset).

EDIT I suspect he wants to use a separate RCD for his sensitive stuff to avoid it going off with the rest of the house.

[Forkinhades]

OK to be clear, if you want to supply the second circuit via an unprotected cable. Then supply side of Safety-Cut. Then protect the load via RCCB

[Chao Lao Beach]

OK, to be honest I didn't check again before posting, they may be B & C breakers, any way they are different and I was wondering why, the sparky says same same.

Sorry I was not super clear, I sent a PM to Crossy beofre and I didn't want to annoy him again ! All I did was move the location to annoy !!!

The RCCB in the house gives many trips, I say false trips but who knows why ? I have a little toy that stays on continously and when it trips, it is a real pain in the but to reprogram it and start again, hence a new circuit beofre the frequently tripping RCCB. It will be 12m cable run distance away, I will buy a new CB box with its own RCCB and earth stake. When I move, I will take the box with me and intend to disable the wire, maybe even remove it if easy to do.

The question is, ow to best conect it with little fuss and protect it. It seems I really should a a breaker next to the join to protect the 12m run as well.

[Forkinhades]

As already suggested you can tap in to the live side of your safety - cut. I would mount a single MCB with enclosure next to your CU. Protected by a 10A MCB (type B if you can get one) then run your cable to your said position. You can add additional via RCCB at the load end.

Point to add is that if you have an MEN connection, then it is quite possible that your MCB type B will open in time to comply with any regs!

[Forkinhades]

Some pictures would be helpfull

[bankruatsteve]

Perhaps the easiest and cheapest way to both isolate and protect your spur run is to get the ubiquitous knife blade DPST switch (Chang brand?) and fuse it for 20a.

[Forkinhades]

Also point to add with the type B and C. If you use type B, then your impedance values double! Without getting too technical it means that your protective MCB could quite possibly comply without need of RCCB (16th)