Can an upstream fault cause an RCBO to trip?

Knobhead · Sep 17, 2011

I don’t know how long you’ve been in the game Llandrillo but you’d better get used to being told things in little bits.

There are times when you have to be like Sherlock Holms to find a fault. A bit of information here, a bit from there and eventually you get the full picture. (If you’re lucky).

LlandrilloSpark · Sep 17, 2011

Prob not as long as you Tony!, Thats the thing with this job, 5 different staff members and lots off different guests telling them what happened, I asked the main manager to open up a faults log and ask the customers the usual Q'S, what did you press, what did you hear, did you smell anything, what was on in the room when it tripped.........2 weeks later no log so im changing little things each visit to see if they have an impact, bottom line is this company use cheap crap in their installations i have found faulty lamps ect, but like ive mentioned the biggest effect has been switching the RCBO type, the other problem is the contract is not mine, im working on behalf of a much bigger firm and i dont have the authority to change all the lamps, switchgear or accessories so i have to ask, also because the place is full i have a limited window each day im available to get in to the rooms.......nightmare.

pushrod · Sep 17, 2011

Just a real longshot - intercom in the lift or staff walkie talkies?

LlandrilloSpark · Sep 17, 2011

both present in the building pushrod, but cant be the walkie talkies as they are used through out the building

Rockingit · Sep 17, 2011

I'm REALLY reaching at a guess, here, BUT... if this is a hotel scenario (having spent enough time living in the damn things myself) is there any possibility that you could have equipment brought in by guests (thinking laptops and phone chargers) which have inherently higher leakage, together with the possibility of some shoddy earthing?

Either that, or are these the type of rooms where guests are inclined to swing from the chandeliers???

LlandrilloSpark · Sep 17, 2011

Nice try but i reckon a long shot as guests bring items in to all 40 rooms and only 4 effected!

Rockingit · Sep 17, 2011

LlandrilloSpark said:
Nice try but i reckon a long shot as guests bring items in to all 40 rooms and only 4 effected!

Appreciated, but my thoughts were more towards the possibility of those four rooms having some commonality of earthing, hence just those rooms affected.

LlandrilloSpark · Sep 21, 2011

Quick update

The room which tripped on a daily basis has not tripped since the RCBO was changed from type B TO C, and its been fully occupied for 8 days, with no earth leakage on the final circuits its a bit of a mystery?!, faulty RCBO or as suggested hight start up current upstream.

nickblake · Sep 21, 2011

Bet you its the coffee machine ......it would be if i was there lol

pushrod · Sep 21, 2011

One of the world's great unsolved mysteries - maybe all of the suicidal spiders that lived near the CU are now all dead.

It certainly shows the downside of rcbos compared to rcd+Mcb. Yes they might minimise inconvenience, but when it comes to a problem you don't know whether you are starting with an overload or an earth fault.