I want to test my 240v hookup, sockets, MCB etc, before I actually plug it in, is this something I can do myself or is it best to get an electrician in? is it a case of checking continuity of wires etc, and does anyone know if , when tested you should get some sort of certificate? and will an electrician need to see everything as i've installed all the wiring as stealthy as poss and don't really want to dismantle stuff.
240v Safety
- Thread starter mark aris
- Start date
This is a very grey area. If you have fitted the correct kit you should have a test button on your RCD. Use it. Have you bonded the earth to the vehicle body? Other than that there isn't much to test and assuming that you have made good and proper connections there is no reason why it wouldn't be safe.
Contributing as a spark ..
Prior too energizing any new work oit additions to existing circuits there are set dead tests to complete using special test equipment ....
Then live tests once the dead tests are done ...
Pushing the RCD test button is no substitute for proper testing I'm afraid...
I bought a plug online which lights up. I use it when I hook up to a new campsite to check that their supply is wired correctly etc. I also used it when I wired my van and plugged it into my house for the first time. I figured if there was an issue the box in the van would trip or the one In the house.
Sparks will probably cringe at what I just said but it worked
Sparks will probably cringe at what I just said but it worked
Maybe not on a complex installation. On a a very simple set up like this it is not much different to running an extension lead. Would you test one of those every time you use it? I understand what you are saying form your professional stand point but you also have to be realistic.
Sparks cringe at everything that isn't by their book!
P
Phil_G
Guest
Thats true, but even sparks aren't infallible. When we moved in, the previous owners explained that one of the two kitchen lights had never worked.
Shortly afterwards Kez got a belt off the pattress screw so I took a look, recognised it as a two-way with the yellow/green as a live return - but the spark had assumed the yellow/green was earth & had screwed it to the pattress earth terminal. Admittedly it had been wired with the wrong colours (by another spark?
) but the assumption could have had a nasty outcome! It now works fine as a two-way and the yellow/green has red heatshrink both ends and a written 'live' label!
Incidentally its easy to test an RCD but you must be aware of what you're doing.
In a very small nutshell an RCD checks that whatever current goes out on the live, the exact same current also returns on the neutral. If there is any difference between what goes out and what comes back, then it must be going somewhere it shouldnt, like to earth via your body! A difference of only 20mA will trip the RCD and cut the power, so its easy to make a test-probe with an earthed 10k resistor, when touched to either live or neutral it should trip the RCD. Obviously you dont do any of this if you need reminding that you're dealing with lethal voltages and that you mustn't electrically touch anything during the test
Incidentally, I've spoken to a couple of reputable sparks who didnt know the functional difference between an MCB and an RCD. Scary!
Shortly afterwards Kez got a belt off the pattress screw so I took a look, recognised it as a two-way with the yellow/green as a live return - but the spark had assumed the yellow/green was earth & had screwed it to the pattress earth terminal. Admittedly it had been wired with the wrong colours (by another spark?
) but the assumption could have had a nasty outcome! It now works fine as a two-way and the yellow/green has red heatshrink both ends and a written 'live' label!Incidentally its easy to test an RCD but you must be aware of what you're doing.
In a very small nutshell an RCD checks that whatever current goes out on the live, the exact same current also returns on the neutral. If there is any difference between what goes out and what comes back, then it must be going somewhere it shouldnt, like to earth via your body! A difference of only 20mA will trip the RCD and cut the power, so its easy to make a test-probe with an earthed 10k resistor, when touched to either live or neutral it should trip the RCD. Obviously you dont do any of this if you need reminding that you're dealing with lethal voltages and that you mustn't electrically touch anything during the test
Incidentally, I've spoken to a couple of reputable sparks who didnt know the functional difference between an MCB and an RCD. Scary!
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Very nice Phil.
I've never really completely understood how an RCD works, despite watching videos on YouTube, and now I doThats true, but even sparks aren't infallible. When we moved in, the previous owners explained that one of the two kitchen lights had never worked.
Shortly afterwards Kez got a belt off the pattress screw so I took a look, recognised it as a two-way with the yellow/green as a live return - but the spark had assumed the yellow/green was earth & had screwed it to the pattress earth terminal. Admittedly it had been wired with the wrong colours (by another spark?
Incidentally its easy to test an RCD but you must be aware of what you're doing.
In a very small nutshell an RCD checks that whatever current goes out on the live, the exact same current also returns on the neutral. If there is any difference between what goes out and what comes back, then it must be going somewhere it shouldnt, like to earth via your body! A difference of only 20mA will trip the RCD and cut the power, so its easy to make a test-probe with an earthed 10k resistor, when touched to either live or neutral it should trip the RCD. Obviously you dont do any of this if you need reminding that you're dealing with lethal voltages and that you mustn't electrically touch anything during the test
Incidentally, I've spoken to a couple of reputable sparks who didnt know the difference between an MCB and an RCD. Scary!
They aren’t reputable then ......
P
Phil_G
Guest
...and worse, they didnt appreciate the significance of the trip & the load specifications of an RCD. I'd asked for an 80mA master RCD upstream of all the 20mA distribution ones, but he brought an 80 amp, 20mA trip RCD and argued it was the same thing.
Poor sparks can be scary
Poor sparks can be scary
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For anyone interested This is the plug I keep in the camper to test site supplies are ok https://www.amazon.co.uk/Winner-Mai...ket+tester&dpPl=1&dpID=41Yrl1aIMpL&ref=plSrch
I have the same one, leave it in one of my sockets permanently
P
Phil_G
Guest
Same thing from B & Q.
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The problem with these simple plug in testers is that they do not tell you how 'good' your earth connection (and therefore primary protection from electrical shock) actually is. They will tell you if the polarity is wrong (reversed Live and neutral) but they do not stress test the earth connection. So under a true fault condition, the earth may not be effective.
An appropriate RCD will come to your rescue but you should ensure a good earth circuit.
D.
An appropriate RCD will come to your rescue but you should ensure a good earth circuit.
D.
P
Phil_G
Guest
Agreed, but since the only true earth connection on a camper is the one that comes down the EHU lead, and the van is otherwise isolated by its rubber tyres, a poor or absent earth and a live touch might not give much of a shock anyway if theres no circuit to earth. On the other hand if you're stood just outside the van and touch something live inside, the RCD should definitely trip, independent of the van's earth - though RCD's aren't instant so you may still get a sting
Bottom line is if this is your field then you know all this, but if you're not sure, then a check by someone who is would be worthwhile if only for peace of mind
Cheers
Phil
Bottom line is if this is your field then you know all this, but if you're not sure, then a check by someone who is would be worthwhile if only for peace of mind
Cheers
Phil
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P
Phil_G
Guest
Remember making an electro-magnet in science lessons at school, winding enamelled copper wire round a nail?I've never really completely understood how an RCD works, despite watching videos on YouTube, and now I do
An RCD is just an electromagnet but with two coils set in opposition, one coil in series with the live - lets call that the 'outbound' coil, and one in series with the neutral which we can call the 'return' coil. Under normal circumstances the outbound and return current is the same, so theres no overall magnetism as the opposing coils cancel each other out. If however, you touch a live terminal with your finger, some current flows through your body to earth, the returning current is therefore less than whats going out, the two coils are no longer 'balanced' and theres an overall current through the two electromagnet coils which energises it as a magnet. It attracts an armature which trips the release mechanism that has been holding the contacts together, and so cuts the power before you frazzle.
Domestic RCDs are generally set to trigger on a difference of 20mA which isnt a fatal level. Regardless of how much current flows, ie a little night light or a 3-bar electric fire, the outbound and return current should normally be the same, and its a difference in current 'outbound vs return' that triggers the RCD. EPLS
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What's a shock between mates!!
Give us something to talk about other than crap headlights.
Ahh there's a thought....would wiring the H4s to the mains help??
PS, I have nothing constructive to say about 240v site electrical safety. Sorry.
Give us something to talk about other than crap headlights.
Ahh there's a thought....would wiring the H4s to the mains help??
PS, I have nothing constructive to say about 240v site electrical safety. Sorry.
