Full rcbo boards????

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D00DY_T00DY

D00DY_T00DY

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Hi all,

Probably going to seem like a novice question just wondering what techniques you lot have for full rcbo boards to keep it neat.

Put 5 in today for a temporary supply for ground workers on a genny; earth rod with a Zs of 2.13ohms (fairly good?)

Anyway it was a complete nightmare trying to keep it neat with the earth and neutral flexes out of them.

I've only installed less than 10 just wondering all your techniques for rcbos?

I kept all the length on these and tried to coil them nicely behind the cpc and neutral terminals.
 
I cable tie them and loop them behind incoming L-N and splay them up to the terminal. Was thinking of ferruling them with shorter cable. The functional earths are crazy though at what .5mm? and also long, it is a bit messy and annoying I have to work with such tat.
 
Vortigern said:
I cable tie them and loop them behind incoming L-N and splay them up to the terminal. Was thinking of ferruling them with shorter cable. The functional earths are crazy though at what .5mm? and also long, it is a bit messy and annoying I have to work with such tat.
Click to expand...
Some say there isn't actually a conducter In there at all :D

I tried connecting all the rcbo flexes out then get them all together then connect my circuits but fighting 6mm wires round was just a pain so I'm thinking circuits first then move the flex round the circuit wires and cable tie them all together.

It'll be a while till I'm installed rcbos again though.
 
I agree, I did an 8 way Wylex the other day and was doing great with neatness which all went to pot with the functionals and the neutrals. I cable tied across in a group of 2 then splayed.
Good experience though. Was a small dimension board though as it had to fit in a meter box!
 
Well indeed a spark I know just connects even the functional earth to neutral. It does get me though as the FE is so small and mixing sizes in the same termination is somewhat unreliable.
 
I know Memshield 3 isn't the same quality as Memshield 2 but the rcbos have no earth lead.
 
D00DY_T00DY said:
Hi all,

Probably going to seem like a novice question just wondering what techniques you lot have for full rcbo boards to keep it neat.

Put 5 in today for a temporary supply for ground workers on a genny; earth rod with a Zs of 2.13ohms (fairly good?)

Anyway it was a complete nightmare trying to keep it neat with the earth and neutral flexes out of them.

I've only installed less than 10 just wondering all your techniques for rcbos?

I kept all the length on these and tried to coil them nicely behind the cpc and neutral terminals.
Click to expand...
Stick some functional earth coloured sleeving over them cut to length, nice and neat no problems imo
 
Cut and ferrule for me every time.

Like to leave a little bit length still so the RCBO isn't completely useless if it does need to be moved a little in the future.

after.jpg
 
I beg to differ. RCBOs are far better than the dual RCD boards with massive tails cluttering up the whole space. I just cut the neutral lead down to size and fit a 4 or 6mm2 boot lace ferrule. These things cost pence. As for the f/earth , take them to below the bus bar, into a wago 222 then take a 2.5mm2 single from wago222 up to earth bar. Also if you are installing C/U as a replacement there is much less chance of nusance tripping.
 
telectrix said:
very neat, mate.
Click to expand...

Was done last year for my CPS assessment, looking at it now (a year down the line) and I'd argue there's room for improvement. I think if I'd done it today I'd have learnt a few more tricks and it would be neater still.

Thought I had some photos of a Proteus (absolute s****) 3-phase board I done recently where I'd cut and ferruled but I've checked and seems I didn't bother to get the camera out.
 
I know the kqi Schneider rcbo instructions tell you not to bundle the neutrals together but can cut to length.
They recommend if the functional earth is cut then a bootlace is fitted due to crushing of the fine strands when tightend in the terminals
 
My boss used to unwrap the coiled leads and hang them from a table at night. Gives you a nice straight tail then. I always shorten and ferrule, that said the SBS is a good option.
 
Rcbo tails should be cut to length and not bundled up in the board as this can lead to overheating of the conductor. Some, such as Schneider, even have this detailed in the instructions.

I'm curious about the Zs quoted in the OP, any Zs measurement on a generator fed installation won't include the earth rod, it will be testing the return path directly to the star point of the alternator.
The Ra for generator earth rods has to be measured using an earth electrode testing method.
 
I got a Ra of 4 ohms the other day tho I used the structural steel as the electrode.
All bolted together about 10 lengths of steel into the foundations.
 
Ian1981 said:
I know the kqi Schneider rcbo instructions tell you not to bundle the neutrals together but can cut to length.
They recommend if the functional earth is cut then a bootlace is fitted due to crushing of the fine strands when tightend in the terminals
Click to expand...
Temporary supply mate, might be in a month max. Probably try blag the company to give him the cable and gear back since they won't use it :D did on the last tempory supply we did haha
 
D00DY_T00DY said:
Boss does the testing, I took a Zs at the board after I finished. That's what I was referencing
Click to expand...

Does your boss not include you in the testing process? Did you see him set up temporary electrodes and test the earth rod at any point in time?

Your Zs measurement almost certainly did not include the earth rod. You will have been testing via the cpc straight back to the star point via the N-E link at the generator

With a generator fed installation the earth electrode is the earth reference of your TNS system. In comparison to a normal installation the generator is equivalent to the substation transformer.
 
D00DY_T00DY said:
Wonder if it actually makes a difference or it's just them putting their tin hats on.

Duely noted though.
Click to expand...

Yes it does make a difference, cables bundled tightly together get hot. I've replaced a couple of rcbos with overheated neutral tails over the years, some from bundling up and some from a lack of ferrules. It's always been on the larger sizes of rcbo where the neutral tail is seeing it's full rated current.
 
davesparks said:
Does your boss not include you in the testing process? Did you see him set up temporary electrodes and test the earth rod at any point in time?

Your Zs measurement almost certainly did not include the earth rod. You will have been testing via the cpc straight back to the star point via the N-E link at the generator

With a generator fed installation the earth electrode is the earth reference of your TNS system. In comparison to a normal installation the generator is equivalent to the substation transformer.
Click to expand...
Yeah the rod doesn't form part of the earth fault loop impedance path so an earth electrode tester is the only way to test the electrode.

I was given a value of below 200 ohms which is also mentioned in the on suite guide for installing generators over 10kva.
I know the supply electrode at the transformer end in a substation set up is normally quoted at 21 ohms max.

Ze Seams high tho if the generator is a TNS which they normally are.
 
Last edited:
davesparks said:
Does your boss not include you in the testing process? Did you see him set up temporary electrodes and test the earth rod at any point in time?

Your Zs measurement almost certainly did not include the earth rod. You will have been testing via the cpc straight back to the star point via the N-E link at the generator

With a generator fed installation the earth electrode is the earth reference of your TNS system. In comparison to a normal installation the generator is equivalent to the substation transformer.
Click to expand...
Hardly if ever. Going to ask soon since I'm going into my forth year in July.

I didn't see him do that. Haha looks like he's been caught out.

Main supply is coming in soon, the company wants it connecting upto that once it gets put in.
 
D00DY_T00DY said:
Hardly if ever. Going to ask soon since I'm going into my forth year in July.

I didn't see him do that. Haha looks like he's been caught out.

Main supply is coming in soon, the company wants it connecting upto that once it gets put in.
Click to expand...

There are a scary number of electricians who don't seem to understand the subject. A lot of electricians don't go near independent generator supplies and so never have the need to think about it.
 
The only thing I don't like about RCBO's, is there's no obvious sign as to whether it's the rcd or mcb element that has tripped. I understand most user instructions suggest trying to reset 'once', and sparks flying out of the thing might give the game away, but you'd think the manufactures might of developed some form of visual indicator (someone's gonna tell me there is). Seem to recall the early MK RCBO's tripped to the half way point, if it was the rcd?
 
Think the regulation is every connection shall have adequate mechanical strength and be suitable for the terminal or something along those lines
 
spinlondon said:
Regs don't require ferrules be fitted.
They require the fine stranded wire be protected against damage from the screw terminals which can be satisfied by twisting and then doubling over the strands.
Click to expand...

The requirement is that the conductor ends be suitably treated, which as usual is as clear as mud.
But, twisting and doubling over does not provent the strands from being broken when the screw is tightened, if you undo the screw and take the conductor out you will find a number of broken strands.
Ultrasonic welding and ferrules are the two commonly used methods which actually work.
 
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