Joining Armoured Cable together.
- Thread starter psd99
- Start date
So, there are a number of devices in your consumer unit.
MCBs: Each circuit has an MCB - Miniature Circuit Breaker. This has a curve type (A, B, C etc, usually B Curve for home) and an Amp rating (e.g. rings on 32A, etc). It will trip out if too much current passes through the live.
RCD: Commonly twice the width of the above, has a test button on it, and measures the balance in the live vs the neutral. A difference over the rated allowance (usually 30mA) between live and neutral, and it trips. Has a test button on it. Effectively, this device is looking for the same current going out of live to be coming back in via neutral. If some current is going elsewhere (down the earth, through your leg, whatever) it trips. These usually cover multiple MCBs, and, crucially, any leakage will cause them to trip. So for example, you might think "it must be the garage, because even when all the other MCBs are off it still trips" but even if you've turned an MCB off, that's only isolated the live for that circuit. So some device with a short between neutral and earth that is currently completely unpowered on a circuit that is off, could still cause the RCD to trip.
RCBO: RCBOs combine the functions of an RCD with an MCB, and are the width of an MCB. They are newer and more expensive (£30 each rather than £3-4 each) but by having an RCD for each circuit, a fault only takes out that circuit and doesn't leave you sat in the dark.
Personally I like to have RCBOs on everything, it makes things much easier.
In any case, as long as the live and neutral are intact, what you have or have not done to the earth is irrelevant and won't trip the RCD. The RCD will only trip if there is a difference of current going out the live vs coming back in the neutral. Nicking the SWA cable and exposing the armour (which should be earthed, but isn't in your image, although might be at the other end) CANNOT have caused the RCD to trip, unless you hit it so badly that you went through the armour.
MCBs: Each circuit has an MCB - Miniature Circuit Breaker. This has a curve type (A, B, C etc, usually B Curve for home) and an Amp rating (e.g. rings on 32A, etc). It will trip out if too much current passes through the live.
RCD: Commonly twice the width of the above, has a test button on it, and measures the balance in the live vs the neutral. A difference over the rated allowance (usually 30mA) between live and neutral, and it trips. Has a test button on it. Effectively, this device is looking for the same current going out of live to be coming back in via neutral. If some current is going elsewhere (down the earth, through your leg, whatever) it trips. These usually cover multiple MCBs, and, crucially, any leakage will cause them to trip. So for example, you might think "it must be the garage, because even when all the other MCBs are off it still trips" but even if you've turned an MCB off, that's only isolated the live for that circuit. So some device with a short between neutral and earth that is currently completely unpowered on a circuit that is off, could still cause the RCD to trip.
RCBO: RCBOs combine the functions of an RCD with an MCB, and are the width of an MCB. They are newer and more expensive (£30 each rather than £3-4 each) but by having an RCD for each circuit, a fault only takes out that circuit and doesn't leave you sat in the dark.
Personally I like to have RCBOs on everything, it makes things much easier.
In any case, as long as the live and neutral are intact, what you have or have not done to the earth is irrelevant and won't trip the RCD. The RCD will only trip if there is a difference of current going out the live vs coming back in the neutral. Nicking the SWA cable and exposing the armour (which should be earthed, but isn't in your image, although might be at the other end) CANNOT have caused the RCD to trip, unless you hit it so badly that you went through the armour.
Associate
- Joined
- 22 Mar 2004
- Posts
- 701
Where exactly is that jointbox?
It looks to me it's open to the elements and certainly not IP rated. I wouldn't be suprised if the amount of crap and debris within that JB is causing a low insulation resistance between the cores which will most certainly trip a RCD out.
Either way, as said above, it's a proper mickey mouse installation.
It looks to me it's open to the elements and certainly not IP rated. I wouldn't be suprised if the amount of crap and debris within that JB is causing a low insulation resistance between the cores which will most certainly trip a RCD out.
Either way, as said above, it's a proper mickey mouse installation.
Associate
WtF is that mess i would not be able to sleep at night LOL
hi well the electricity in the garage has been okay last few days
even when it rained so heavy!
I find this a strange situation
actually the installation for this wire could have been a lot worse.
I was in a situation where there was so much works going on and little things like this got missed out
I actually had a lot of paving/turf that I would do myself almost 6 months later, therefore wherever this cable was did not make a difference to me at the time.
Anyways I don't know what I'm going to do yet but thinking of digging some of the turf up next time it won't turn on to see if the cable has been nicked or not in a place I suspect it has happened.
even when it rained so heavy!
I find this a strange situation
actually the installation for this wire could have been a lot worse.
I was in a situation where there was so much works going on and little things like this got missed out
I actually had a lot of paving/turf that I would do myself almost 6 months later, therefore wherever this cable was did not make a difference to me at the time.
Anyways I don't know what I'm going to do yet but thinking of digging some of the turf up next time it won't turn on to see if the cable has been nicked or not in a place I suspect it has happened.
I will clean the junction box out tonight properly.
just found it weird how everything was good before the turfing now not so great (except all this week when the circuit started to work)
Thanks that is good to know
the main purpose of getting electricity to the garage is for the fridge that I will put in there eventually.
so what is your theory in all of this?
Soldato
I wonder if you have a loose connection somewhere if its now working fine, as you have been poking around you may have "fixed" the weak point
I would have a good check that all the cables are securely tightened. Also look for any visible damage where they are exposed from the armouring.
I guess its also possible the armouring was touching something it shouldn't!
My armoured cable has these on it for example (self laid but under advice/guidance from works elec manager)
http://www.screwfix.com/p/tower-external-gland-kit-20s-ip66-pack-of-2/25996
The armoured part terminates inside the glands, that way only the wires come out from inside the gland (into distribution or socket or whatever you are connecting to)
I would have a good check that all the cables are securely tightened. Also look for any visible damage where they are exposed from the armouring.
I guess its also possible the armouring was touching something it shouldn't!
My armoured cable has these on it for example (self laid but under advice/guidance from works elec manager)
http://www.screwfix.com/p/tower-external-gland-kit-20s-ip66-pack-of-2/25996
The armoured part terminates inside the glands, that way only the wires come out from inside the gland (into distribution or socket or whatever you are connecting to)
turned off again yesterday
mrs was using the oven and said it tripped a few times then when the oven was off it did that again
garage switch just wouldn't work so I left it turned off and everything is fine so far.
electrician didn't turn up yesterday as he was messing me about with times etc so will reach out to him again. frustrating no doubt!
mrs was using the oven and said it tripped a few times then when the oven was off it did that again
garage switch just wouldn't work so I left it turned off and everything is fine so far.
electrician didn't turn up yesterday as he was messing me about with times etc so will reach out to him again. frustrating no doubt!
What do you have plugged in to the circuit in the garage?
You can do a bit of basic trouble shooting by unplugging everything and seeing if the problem persists. If it doesn't, it could well be linked to an appliance.
Do this during a period of tripping so that you can see if unplugging everything helps or not.
Also, your armoured cable, does it run straight from your main circuit board or is it spurred off a plug socket? Assume its wired directly as the cooker should be on its own circuit anyway.
You can do a bit of basic trouble shooting by unplugging everything and seeing if the problem persists. If it doesn't, it could well be linked to an appliance.
Do this during a period of tripping so that you can see if unplugging everything helps or not.
Also, your armoured cable, does it run straight from your main circuit board or is it spurred off a plug socket? Assume its wired directly as the cooker should be on its own circuit anyway.
Hi, it runs on it's own circuit
nothing is plugged into the garage
all sockets are off. Might be something to do with the oven. let's see what he says...
yes they are on the same RCD circuit as each other.
not sure what you mean by oven fuse? We got a switch on the wall that just turns off yes no light etc.
Your oven should be (I assume) on a circuit by itself and so will have a circuit breaker / Fuse in the main fuse board. Your fuse board will have maybe 2 RCD's that each have a number of circuits associated to them, an example of one RCD setup would could be your oven, the garage, then maybe lights down, and sockets down? This is just an example.
From what you are saying I assume it is the RCD that is tripping on the side that has the garage and oven circuits on it, and your initial thoughts are its that that is the garage circuit that is causing the RCD to trip out.
From what you are saying I assume it is the RCD that is tripping on the side that has the garage and oven circuits on it, and your initial thoughts are its that that is the garage circuit that is causing the RCD to trip out.
update
so far so good - not had a trip out even though it has been raining
electrician came out and said that this is quite a common issue and it's due to the RCD being a good distance from the garage and there is not enough earthing in place. I don't know if he is trying to fob me off but he said the tests for live and neutral were good he tested this both with the main switch off and on and found no problems with the cable?
his solution was to earth the armoured cable with a rod into the ground but I am not convinced
does he have a point here or not?
so far so good - not had a trip out even though it has been raining
electrician came out and said that this is quite a common issue and it's due to the RCD being a good distance from the garage and there is not enough earthing in place. I don't know if he is trying to fob me off but he said the tests for live and neutral were good he tested this both with the main switch off and on and found no problems with the cable?
his solution was to earth the armoured cable with a rod into the ground but I am not convinced
does he have a point here or not?
That's some shoddy work for sure.
First thing I'd do is change that junction box! I don't know if it's placed inside or outside but somebody has just used a junction box made for the inside, usually for lighting circuits. I've seen bugs blow circuits because they've wandered across live terminals, never mind water. I'd recommend one of these:
Using the appropriate armoured cable gland too.
Then in your shed use a garage consumer unit, again with a proper gland on the armoured cable:
That way if something trips in the shed while you are away it won't trip anything in the house.
First thing I'd do is change that junction box! I don't know if it's placed inside or outside but somebody has just used a junction box made for the inside, usually for lighting circuits. I've seen bugs blow circuits because they've wandered across live terminals, never mind water. I'd recommend one of these:
Using the appropriate armoured cable gland too.
Then in your shed use a garage consumer unit, again with a proper gland on the armoured cable:
That way if something trips in the shed while you are away it won't trip anything in the house.
Soldato
Is it the same one who installed it?
If not did he not mention it's a really bad install and should be like above?