Jump to content

DONT STAY LURKING AS A GUEST,

JOIN TEF AND BENEFIT FROM MEMBERSHIP:

CLICK HERE TO JOIN.
  • 0

explanation if you please...


betty swollocks

Question

this is a second hand job, basically a friend who is a spark has asked me for some advise and i couldn't help and thought someone here might.

two portacabins side by side,

both have

1, 2way c/u with rcd main switch, 20a mcb for two sockets, 6a mcb for 2 external bulkhead lamps and 2 5' flo lights

the second cabin is fed from the supply of the first via a swa laid underground, length @ 4m

both are supplied from a generator, type/kind, i have no idea

problem is that every morning when the genny is fired up the lighting in portacabin 2 will not work even if the swithes are in the on position until both mcbs and rcd are turned off then back on again at the c/u

switching the light switch has no effect either

turning just the lighting breaker/just the socket breaker or just the rcd alone dosent work, it has to be all 3, my mate has tried and confirmed this,

there is nothing plugged in the sockets in either cabin but the outlets are powered up on starting the genny

lighting in cabin 1 works perfectly

my mate is almost retired and hasn't done any testing other than flicking the switches and plugging socket tester in sockets..:|

i have no other info to go on at the moment

can anyone shed any light lol :coat or offer an explanation,

its about 80miles to the site and although i've been asked to go at the weekend i would rather go thinking i could sort it.

thanks

Link to comment
Share on other sites

16 answers to this question

Recommended Posts

they are left on, lights in 1 come back on as genny fires up, cab2 as described

Link to comment
Share on other sites

You have a gremlin. You need a priest not a spark...........

If it works when you switch it all on and off then the fault has to be in the second CU - that's the only thing it can be - it's the only thing that is altered by doing what is done.

You could take some components but why not just get a garage CU fully loaded and get your spark mate to swap it.

http://www.screwfix.com/prods/63138/Electrical-Supplies/Consumer-Units/Volex-Consumer-Units/Volex-2-Way-RCD-Garage-Consumer-Unit?cm_re=SEARCHPROMO-_-GARAGE%20CONSUMER-_-63138

Link to comment
Share on other sites

Think apache has right approach, but would suspect RCD as main culprit, and corrosion on contacts to be cause of agro???? (hence switching cleans contacts and returns supply) Swap RCD/MCBs and see what happens.

Link to comment
Share on other sites

problem is that every morning when the genny is fired up the lighting in portacabin 2 will not work even if the swithes are in the on position until both mcbs and rcd are turned off then back on again at the c/u

switching the light switch has no effect either

turning just the lighting breaker/just the socket breaker or just the rcd alone dosent work, it has to be all 3, my mate has tried and confirmed this,

there is nothing plugged in the sockets in either cabin but the outlets are powered up on starting the genny

Is the RCD tripping when the genny is fired up?

or is it staying on?

Could there be some sort of small earth leakage within the wiring...

trips RCD as genny first kicks in before it stabilises itself?

could any damp / condensation build up be a problem..

my mate is almost retired and hasn't done any testing other than flicking the switches and plugging socket tester in sockets..:|

Personally I would want to test continuity polarity etc.. across all switches & cables before power up genny.

Then power genny see what happens...

and test whereabout along the circuits any voltages have got to??

i.e.

is voltage getting through the RCD, MCB's switches???

I think you have got to treat this as if it were a new rewire..

back to basics test all the stuff out

assume NOTHING is wired correctly..

As Patch says take a spare 2-way CU..

or even Two spare CU's

:|

Link to comment
Share on other sites

I would guess its got damp at some point and its tripping out but due to dirt/rust/something else, the switch is not moving enough to show it as off but a manual off/on fixes it. Could also check all the connections are tight in cu2 too (and no insulation is in the terminals).

You say cu2 is fed from cu1, is that from the 20A mcb for the sockets in cu1? Do the sockets work in both cabin1 and cabin2 even when the lights do not? If so, then I can not see how it could be the RCD otherwise both the sockets and the lights are off. If it is just the lights (sockets still work) then I would suspect the 6A mcb. Will the lights come on if the 6A mcb is turned off and the RCD too with the sockets left on (i.e. stopping power to the 6A mcb) as that could indicate some kind of quasi state the MCB gets itself into that de-energising it sorts out?

Ian.

Link to comment
Share on other sites

are you sure the RCD is fully on? some RCD/MCB dont move fully to off if they trip, they move part way. maybe its an active RCD so need re-set after each power loss (although most RCD's for CU's etc are passive)

Link to comment
Share on other sites

are you sure the RCD is fully on? some RCD/MCB dont move fully to off if they trip, they move part way. maybe its an active RCD so need re-set after each power loss (although most RCD's for CU's etc are passive)

Indeed...

MK have a half-way trip point...

Link to comment
Share on other sites

Not that I know much (if anything) about gennys,,,

But,,,

Could it be something like the voltage regulator in the genny doesn't like being started on load???

Link to comment
Share on other sites

guys the electrics are fairly new as far as i know, less than 3 months, but cabin 2 problem has it seems always been like that although its only just come to light?!? hmmm

cabin one works perfectly, i.e. lights and sockets powered up, genny turned off at night and back on next morning, lights come on as they should as lightswitches are in the 'on' position and sockets work, not so in cabin 2, sockets work but lights dont, flicking individual light switch changes nothing, same for flicking light 6amcb, hager btw, only way to get lights working is by procedure mentioned.

rcds in both c/u's dont trip neither do mcb's

cabin 2 is fed via the incoming position of cabin 1 rcd, i'e 2 lines/neutrals in the top of rcd - power looped to cabin2

thanks for replys so far, got me stumped to be honest, a few test results would be nice

Link to comment
Share on other sites

are the lights electronic? maybe the start up current/voltage is tripping something, and it only re-sets after being turned off?

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

Terms of UseWe have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.