I have a problem in an amusement arcade, there is a kmf switch feeding an rcd board which is switched off at night. This rcd board has 3 32A breakers feeding socket outlets for machines. Problem, when they come in and switch on the kmf switch the rcd trips out, i think all the machines starting up together is causing it. I wondered if anyone knows if a 30ma time delay rcd is available, the sockets do not feed outside equipment and a socket on the ground floor is available for this purpose.
30 ma rcd time delay
- Thread starter fireman22
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I've never come across a 30mA type S before. I'm mainly involved with the industrial ranges of DBs (MEM, Merlin Gerin etc.) which tend to have a much wider range of wierd and wonderful devices than the domestic stuff but I don't remember ever seeing a 30mA type S. I think the smallest I've ever seen is 100mA....
I've just checked the MEM catalogue, as I expected, I only see 100mA and 300mA as time delays (Consumer i/f prods).
Once you get above 100mS and 100mA you enter the zones of transient cardiac arrest and muscular contraction affecting breathing, the RCDs are more for fire protection than personal safety.
Once you get above 100mS and 100mA you enter the zones of transient cardiac arrest and muscular contraction affecting breathing, the RCDs are more for fire protection than personal safety.
Fireman, your trouble is too much earth leakage on the rcd consumer unit!!
Bear in mind anything with filters (eg PC's , monitors, switch mode power supplies etc) will have high leakage currents to earth. A typical amusement machine may have as much as 1mA leakage. If they have say, 30 machines connected overall (which is probably an underestimate) - then you are on tripping levels already - without any earth fault!! If the unit is fairly loaded up with lots of electrical appliances (as it probably is), then you either need to tell them to cut down on the number of machines they are running from those 3 ring circuits , or if they can't do that then install individual RCBO's for each 32 amp ring.
If the EFLI is low enough then you may get away with a 100mA RCD to cover the whole board - but only if theres no outside sockets.
Considering the public are using these machines and they are all 'Hands On' appliances, keeping them on RCD would be quite wise.
Can't you get them to switch the individual MCB's on instead of throwing the main KMF switch all the time?? Alternatively why not wire the rings into 32A DP isolators , and get them to put the main switch then switch the isolators one by one.
Have you considered changing the 30mA Rcd for a like for like (well branded) version. The latest ones are much better at coping with transients!
Seriously I reckon theres too many machines running from that unit. I have wired an amusement arcade in the past, and I ended up having 6 seperate consumers (60A feeds - 2 consumers per phase) , each with 3 x 20A rings , and each consumer having 30 mA RCD protection across all rings. All because of the known 'High CPC currents' that ths type of equipment have!
Where a situation of tripping occured where there was no circuit fault , reducing the number of appliances (or shifting them to a different consumer circuit ) solved the problems, and now it runs with approx 150 pieces of equipment.
Have they had their equipment PAT tested? Maybe theres a really leaky appliance!!
Bear in mind anything with filters (eg PC's , monitors, switch mode power supplies etc) will have high leakage currents to earth. A typical amusement machine may have as much as 1mA leakage. If they have say, 30 machines connected overall (which is probably an underestimate) - then you are on tripping levels already - without any earth fault!! If the unit is fairly loaded up with lots of electrical appliances (as it probably is), then you either need to tell them to cut down on the number of machines they are running from those 3 ring circuits , or if they can't do that then install individual RCBO's for each 32 amp ring.
If the EFLI is low enough then you may get away with a 100mA RCD to cover the whole board - but only if theres no outside sockets.
Considering the public are using these machines and they are all 'Hands On' appliances, keeping them on RCD would be quite wise.
Can't you get them to switch the individual MCB's on instead of throwing the main KMF switch all the time?? Alternatively why not wire the rings into 32A DP isolators , and get them to put the main switch then switch the isolators one by one.
Have you considered changing the 30mA Rcd for a like for like (well branded) version. The latest ones are much better at coping with transients!
Seriously I reckon theres too many machines running from that unit. I have wired an amusement arcade in the past, and I ended up having 6 seperate consumers (60A feeds - 2 consumers per phase) , each with 3 x 20A rings , and each consumer having 30 mA RCD protection across all rings. All because of the known 'High CPC currents' that ths type of equipment have!
Where a situation of tripping occured where there was no circuit fault , reducing the number of appliances (or shifting them to a different consumer circuit ) solved the problems, and now it runs with approx 150 pieces of equipment.
Have they had their equipment PAT tested? Maybe theres a really leaky appliance!!
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its a bit of a pricey option but you could do away with the RCD at the consumer unit altogether and use RCD plugs or sockets
or you could not RCD protect the stuff at all i don't belive there is any reg requiring it to be on RCD.
or you could not RCD protect the stuff at all i don't belive there is any reg requiring it to be on RCD.
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