Sanity check, RCD or what.....

Gringoking88 · May 27, 2017

Hi all,

A friend of mine has just called me up for a bit of advice and I said I would double check with you guys and girls who are perhaps older and wiser or just wise lol!

He has a coffee shop that has 2 distribution boards of approximately 10 ways each (both split dual RCD boards). One of his staff members called him up saying the power to numerous circuits had gone, but stayed on for others. The first time it went for about 30 seconds then came back on, the second time it went off for about 5 mins then came back on again. He said they were all on one half of one of the boards. My thought process is it can only be a faulty RCCB unit (protecting half the board) but I have never known this before. Does this actually happen or am I completely wrong? It sounds like a mcb fault more than an RCCB fault but I cant explain it with half the board going??

Many thanks in advance,

Martin

Octopus · May 27, 2017

Sounds like an appliance fault, or cabling fault to me.

telectrix · May 27, 2017

or a poor connection on RCD/s, busbar or MCBs. breaking down when under load. busbar incorrectly fitted, i.e. busbar behind MCB cage clamps instead of snugly in the cages.

LankyWill · May 27, 2017

Time to get the test kit out

westward10 · May 27, 2017

Sounds like a lose connection if it re energises itself. Needs attention ASAP.

Gringoking88 · May 27, 2017

Thanks all for the responses. I am told nothing has changed in the shop so would guess maybe the terminals have worked loose. Think I will start hear as sounds like the quickest easiest win lol.

Wilko · May 27, 2017

Protective switchgear is designed to stay off after detecting a fault condition so if power is self restoring it isn't an RCD or mcb, but could be connections to one

Gringoking88 · May 27, 2017

Thanks all, am I also correct in saying an rccb is the same as an rcd?

My thoughts wilko hence why I my mind was more around the unit bei g faulty or having a loose connection.....

telectrix · May 27, 2017

residual current circuit breaker.... residual current device.same thing. just to confuse the uneducated.

Gringoking88 · May 27, 2017

Lol thanks, uneducated like me lol.

westward10 · May 27, 2017

telectrix said:
residual current circuit breaker.... residual current device.same thing. just to confuse the uneducated.

Say again.

Risteard · May 30, 2017

Gringoking88 said:
Thanks all, am I also correct in saying an rccb is the same as an rcd?

Not quite. An RCCB is an RCD but an RCD may not be an RCCB. RCD is a generic term for all such devices, and includes RCCBs, RCBOs, PRCDs, SRCDs etc.

The term RCD is often incorrectly used to refer specifically to an RCCB.

telectrix · May 30, 2017

Risteard said:
Not quite. An RCCB is an RCD but an RCD may not be an RCCB. RCD is a generic term for all such devices, and includes RCCBs, RCBOs, PRCDs, SRCDs etc.

The term RCD is often incorrectly used to refer specifically to an RCCB.

pedant.

Midwest · May 30, 2017

telectrix said:
pedant.

I had to look that up, thought you said pendant

Rpa07 · May 30, 2017

Risteard said:
Not quite. An RCCB is an RCD but an RCD may not be an RCCB. RCD is a generic term for all such devices, and includes RCCBs, RCBOs, PRCDs, SRCDs etc.
The term RCD is often incorrectly used to refer specifically to an RCCB.

If I squint I can see a dolphin jumping out of water!

Midwest · May 30, 2017

I'm shallow, yet I am deep

dmxtothemax · May 31, 2017

If the power to these circuits is coming and going without tripping the RCD's
Then you have problems with a bad/loose/burnt out connection
You should get an electrician in to check it out, or a fire is possible.

bigspark17 · May 31, 2017

I second what @westward10 said a loose connection in rcd or busbar to mcbs

Rpa07 · May 31, 2017

Eicr with the boss and when he was checking tightness of screws there was fizzling - 1 bus bar on wrong side of tightening mechanism. Unfortunately it had seized the mcb so we had to replace. Been like that 12 years!
How long have short courses been around?