RCD Tripping

[madkayaker]

a loose connection can sometimes cause it to pop as the sudden inrush of current can confuse them or maybe (thinking out load) the energy used to create the crack and spark results in a lower return. the RCD is not directly linked to earth (unless old voltage operated ones that are non compliment these days or RCBO when it is reference for the electronics) but N and earth are common at the star point of the supply transformer (the big one feeding the street)

 

[GrahamGKD]

Thanks for those suggestions. I've just checked all of the connections across the consumer unit - the screws securing the incoming tails from the meter were not as tight as I would like them but I don't think loose enough to cause the problem. If the problem continues looks like I need to get the circuits tested then.
BTW, it's definitely an RCD (not an RCBO)
Thanks,
Graham.

 

[mike os]

Rcd can become faulty, probably worth changing but must be the same ratings

 

[GrahamGKD]

OK, the Hypertherm plasma m/c came back today (no fault found - not surprising since after sending it away I have had repeated trips) - I plugged it in and was doing the pressure setting bit (not even started cutting) when bang, off went the power. I'll wager that that was the exact moment when my new Hydrovane decided the tank needed topping up and tried to start. Also, the air system I have connected to the Hydrovane is a bit leaky so the machine cuts in to pump up every now and again - I'd wager that the times the MIG and the shower tripped out the RCD were also times when the Hydrovane was attempting to cut in. That has to be relevant doesn't it?

I've run the Hydrovane on its own for an hour with no problem at all.

I know I should get it tested out properly and all that but I'm a tight fisted git so if I can solve it without spending money getting someone in I will (with your help, of course)!!

I've emailed the supplier of the Hydrovane to see if he has heard of similar problems elsewhere.

Anyone know where I can get a GE RCD (say 80A load, 30mA sensitivity) or one of another make that will fit a 15-18 year old GE consumer unit? There is a secondhand one on ebay but I think I need a new one to rule out the RCD being flakey.
Cheers,
Graham.

Edit addendum: Just started the shower then went out into the shed - air duster on and down it all went again - my problem is the Hydrovane cutting in when there is already a significant load on the system.

 

[the snooper]

with your other items running could it be a simple case of overload when the compressor kicks in.
brightspark measured the inrush of his compressor using a clamp meter and it was 55 amp intial draw then once running it was running as per the rating plate on the compressor

 

[madkayaker]

reer as rocking horse teeth im afraid

 

[GrahamGKD]

with your other items running could it be a simple case of overload when the compressor kicks in.
brightspark measured the inrush of his compressor using a clamp meter and it was 55 amp intial draw then once running it was running as per the rating plate on the compressor

...is the RCD supposed to trip on overload though Snooper? No MCBs are tripping, even though, in the case of the Hypertherm and Hydrovane running together, they are both wired back (via appropriate MCBs in my workshop) to a single 32A MCB in the house? The RCD is supposed to be good for 80A.
Graham.

 

[the snooper]

just checked up and apparently dont detect overload
back to the drawing board for you then

 

[brightspark]

as i said earlier in post the wiring will be down somwhere .putting a large load on anywhere on the circuit tends to knock the trip making u think its the apliance u put on when it goes. but it isnt bite the bullet and get an insulation test done any half decent sparky could tell u whats causing it in 20 mins. pity u wernt local id test it for u

 

[the snooper]

if it only happenes when the power is being used in your garage it would suggest a fault in the garage maybe worth checking the circuit for possible insulation problems in sockets and so on

 

[GrahamGKD]

Phew, this problem is beginning to cause me some serious stress.

I spoke to a domestic electrician but he seemed to think checking the wiring would be nugatory and that the problem was due to the accumulative effects of earth leakage from several sources (e.g. shower in the house and Hydrovane in my shed) and not likely to be a wiring issue. He suggested a time delay RCD but I'm not sure if this would give me or others adequate (or regulatory) personal protection if something goes awry? I don't think he was sure either.

I spoke to Hydrovane - they said similar to above but were unable to suggest what I could do to remedy the situation (although, in fairness, the chap said he would ask around and get back to me). Basically he was saying that RCDs were not recommended in industrial environments for these kind of reasons, although their use is, apparently, becoming more prevalent.

I have discovered that running the Hydrovane through a 25 metre extension cable actually damps down the surge enough to stop the problem happening - not a very practical long term solution though!

I was thinking of going down this route (below) as recommended by Brightspark in a previous thread:

if u want a decent supply to garage as robotstar says split the supply cable between the meter and house consumer unit fit a mains double pole service connector block eg a pair of mains tails out of meter into the twin block then one set to house consumer unit and another set to a 60 amp double pole switchfuse . then run a 16mmm 3 core swa cable out to garage the 3d core being the earth. use earth lugs on glands to bond the outer sheath. if the electricity board supply the eath back at meter u can fit a 5way db in garage with a 60 amp rcd mainswitch unit with 30 ma trip and minature circuit breakers the house services should be bonded eg cas and water supply in 10.0mm earthwire and the earth to the db s from the board supply in 16.0mmm.

I'm not sure it would fix my problem but at least that way I could share the leakage between two RCDs? Maybe the one in my shed could be time delayed if that is legal? The electrician seemed to think that I would need RCD protection of the SWA cable out to the shed though - is that right?

Graham.

 

[brightspark]

Phew, this problem is beginning to cause me some serious stress.

I spoke to a domestic electrician but he seemed to think checking the wiring would be nugatory and that the problem was due to the accumulative effects of earth leakage from several sources (e.g. shower in the house and Hydrovane in my shed) and not likely to be a wiring issue. He suggested a time delay RCD but I'm not sure if this would give me or others adequate (or regulatory) personal protection if something goes awry? I don't think he was sure either.

I spoke to Hydrovane - they said similar to above but were unable to suggest what I could do to remedy the situation (although, in fairness, the chap said he would ask around and get back to me). Basically he was saying that RCDs were not recommended in industrial environments for these kind of reasons, although their use is, apparently, becoming more prevalent.

I have discovered that running the Hydrovane through a 25 metre extension cable actually damps down the surge enough to stop the problem happening - not a very practical long term solution though!

I was thinking of going down this route (below) as recommended by Brightspark in a previous thread:

if u want a decent supply to garage as robotstar says split the supply cable between the meter and house consumer unit fit a mains double pole service connector block eg a pair of mains tails out of meter into the twin block then one set to house consumer unit and another set to a 60 amp double pole switchfuse . then run a 16mmm 3 core swa cable out to garage the 3d core being the earth. use earth lugs on glands to bond the outer sheath. if the electricity board supply the eath back at meter u can fit a 5way db in garage with a 60 amp rcd mainswitch unit with 30 ma trip and minature circuit breakers the house services should be bonded eg cas and water supply in 10.0mm earthwire and the earth to the db s from the board supply in 16.0mmm.

I'm not sure it would fix my problem but at least that way I could share the leakage between two RCDs? Maybe the one in my shed could be time delayed if that is legal? The electrician seemed to think that I would need RCD protection of the SWA cable out to the shed though - is that right?

Graham.

if the electricity board supply the earth back at the house with underground supply and its not overhead tt supply u dont need rcd protection back at the mains also u dont need to use one in the garage on wired in apliances .as all the wiring is surface . not burried in walls . the only protection u need is a 30ma rcd feeding socket outlets if u used a higher amperage eg 100ma trip time delayed thats only to protect the cable and stop nuisanse tripping further back down line

 

[madkayaker]

all circuits in a domestic now need 30mA rcd protection for cables beried in walls, for use by none electricaly compitent persions and all socket outlets. You could use SWA cable from the house (non RCD) to a RCD board in the garage that would comply (presuming installed and certificated by part P compitient persion) that would stop you triping the whole house. Or get the fusebaord changed and get double split or RCBO protection but expect to pay £500 + unless you have a pet electrician WOOF

 

[brightspark]

500 quid talk about take your eyes out . 70 quid for the 17th edition board 14 quid for some 10mm earthwire and a few clips to bond gas and water .1meter of 16 mm earth from mains earth to db a quid . 200 quid for 5 hours work including test. total cost 300 where do u live ??? the center of london RIPOFFwhats the other £ 2oo for im just changin a few 3 phase db s in a school there 500 quid each fitted and im scoring

 

[GrahamGKD]

Nearly there, I think....
My incoming earth is strapped back to the armour of the underground incoming supply (TN-S?). The supply to the shed is T&E for the first bit under the house floor and then SWA up the garden (there is a separate 10mm earth for the first bit and the SWA is 10mm). The wiring in the shed is cable trays and then galv conduit. From what you are both saying I think that means I can use a switchfuse from the meter tails to feed the spur out to the shed? Just leaves the question of how to configure the consumer unit in the shed. Sounds like I could wire the Hydrovane in direct and not use any RCD protection. For my own safety, irrespective of regulations, I want RCD on the sockets. Sounds like I need a split CU for the shed - half RCD and one side just main switch and MCB for Hydrovane? Could just try a split dual RCD CU and swap one RCD out for a main switch and hard wire Hydrovane if that is troublesome? Cheers, Graham.

 

[brightspark]

if u are going to buy a new db for garage just buy a volex split load unit from screwfix one half mainswitch other half rcd protected £40.00 ive got loads of volex breakers spare u can have sum free for the price of the postage

 

[madkayaker]

thats a lot cheeper than many around my way

 

[GrahamGKD]

Update for those still interested.....

I've separated off the supply to the workshop as suggested in a previous thread.

I haven’t fitted the split CU in the workshop yet but as a quick fix I've put the RCD from the new CU into my existing workshop system (temporarily giving RCD protection for the whole system from a single RCD).

Just tried a heap of plasma cutting with this set up and didn't have any trips with the plasma running and Hydrovane kicking in and out. As a belt and braces fix I will split the Hydrovane off to its own RCD protection in due course.

Graham.