Discuss RCBO trip times - no, not the usual what should it be . . . in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

S

Steve_P

I was doing a board change today and 10 out of the 15 RCBO's were returning a value in the region of 19ms at 1x and 30 at 5x. Tried more than 1 MFT (both Metrel but got the same sort of results). So this is still within the 40ms's but with new RCBO's would you personally accept or return them?
 
It passes so what exactly would you say to the wholesaler ...??? I wouldn't worry about it ...sign it off put your invoice in and move to next job ;)
 
Most hager RCBO's give those sort of readings. What is wrong with them.
 
Yeah, I know what you're saying but what if it was 39ms @ 5x? Or even 299.9 @ 1x? At what point on a new bit of kit would you say, naaaaa, that's too close?
 
Ive had a couple recently throw a (excuse the Americanism) curve ball recently, but if its in the set limits then don't worry, someone else spent alot of time and money working out the rules and if one RCBO happens to trip in 180mS when all the other 7 do it in 18 at x 1, then thats fine.

if a little annoying.
 
you dont get out much do you ?
:-D

Not enough mate.

It was just one of those 'on the way home' thoughts really. You know, the ones that creep up on you after what shall I have to eat tonight and oh sod it I didn't do that estimate last night.....
 
you'll tend to find the mechanical elements of the rcbo can be a bit stiff straight out the factory.
repeated tripping with the test button once its fitted can loosen up the internals a bit thus producing a slightly more favourable trip time.
;-)
 
I've not seen it before but reading some of the posts it doesn't seem to be uncommon. Usually I get times very similar with RCBO's. I suppose it's the real reason for this post.
 
It's tripping too fast at 1X?

Nice one, and what is the minimum trip time at 1x?

LMAO you lot are more slippery than a bunch of eels.

There's no complaint. I had a whole load of RCBO's that tripped at 5x higher than they did at 1x and 3/4 time of the max and wondered how high is too high on a new bit of kit, as a general consensus. Is it simply that if it trips, even if it only passes by .01ms it's ok, or does it actually have to fail? Bearing in mind this is new kit we're talking about. Like I've sais, I'm just wondering what you lot think about this.
 
The limits in the regulations are just that, limits. If an RCD trips at 5x Idn in 40.00 ms then it passes, if the RCD trips at 5 x Idn in 40.01ms then it fails.

You can second guess to some extent and choose to ignore this limit if the trip time is faster than 40ms since BS7671 is the minimum standard to which you should work but for strict compliance the 40ms trip time is a pass.
 
Last edited:
Seriously there is no issue here I'm surprised you are that concerned normally if that button works that's enough for me
 
Ok, I give up. I know the limits are the limits. There's no real issue. It's not a Friday wind up. I was just wondering when or if people send new kit back.
 

Reply to RCBO trip times - no, not the usual what should it be . . . in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock