RCD keep tripping with lots of computer equipment

Hi there,

Firstly, I'm not an electrician but an end user.  I've struggled to figure out this problem I have and struggled even more to find an electrician who is willing to even look at the problem when I explain what is happening.

I work mainly from home and have a lot of computer equipment running in the house.  The problem I have is when I power on the server equipment I need for work, the main RCD in the fuse box trips out.  I've managed to get it working to a point that I can power on a single server with just a single power cable installed.  If I plug in the 2nd power cable (they have dual power supplies), the RCD will trip.

My colleague who does the same job has similar equipment in his house.  He had exactly the same problem and we discovered from a website that it has something to do with computer equipment (servers, desktops, laptops) etc all having mini circuit breakers built into them.  Apparently, they make the line very sensitive. (forgive me if what I'm saying is all rubbish - total newbie here).

My colleague fixed his problem by having a new circuit installed with a separate fuse box next to his main one.  This was quite easy to do since everything was in his garage.  Mine is in my utility room so more difficult?

I'm hoping this sound familiar to someone.  I've had one quote from an electrician who never got back to me.  He suggested running all new power to the garage (would prefer the kit to run in there) and that was looking at costing around £1200.  Another electrician said to put in a new fuse box with RCBOs?

Any suggestions on what I can do?  And if anyone is near Milton Keynes, I'm still looking for an electrician to look at this problem.

Without any hands on testing, I would suspect that the cumulative earthing that is leaking is tripping the RCD, an RCD Ramp test would confirm or deny this.

Andy Guinness

Get someone to do a few tests, as Andy said, my first thought would be cumulative leakage. Changing the board and fitting RCBO's may or may not cure the problem, if you have your computer stuff plugged into the downstairs ring as well as getting leakage off the computer gear you will be getting leakage off other stuff that's plugged in too. Then depending on how the house is wired the kitchen may be on the same ring, even more leakage, so in that case putting each circuit on it's own RCBO wouldn't solve the problem.

Try this one, turn off all the breakers in the consumer unit, except the one feeding the circuit that has the computers on it, does the RCD hold? If it does then you may be able to use RCBO's on each circuit. If it doesn't then go around and turn off at the sockets every other piece of equipment that is on that circuit, does the RCD hold now? If it does then fitting RCBO's isn't going to work and you'll need to put the computer gear on it's own circuit, when you do this you'll then have a couple of options, 1 leave everything as it is and add a separate unit to feed the computers, or 2 change the consumer unit for one with RCBO's instead of a single RCD, you'll still need the separate feed for the computers by the way. Changing the whole board would I imagine be a lot more expensive than just adding a second one, but it's up to you, it may be an easy job to get new cables to where the computers are or it may not be . They wouldn't have to be on a ring, they could go on a radial circuit, in which case you could run a single cable, the size could be anything from a single 2.5 twin and earth, right up to a 6mm twin and earth depending on the distance and the load.

computer equipment has a lot of 'smoothing protection' built in, which in short chucks a bit of leccy down the earth cable. 1 PC isn't a problem, but multiple PCs and other equipment will mean that the RCD sees this as a fault, and if that RCD is shared with other circuits in the house you will have earth leakage from other appliances, and constant problems, so there are 2 ways to go:-

1/ change MCBs (circuit breakers) and RCD if shared across multile circuits for RCBOs which combine both functions into 1 unit. This effectively gives you an RCD per circuit so is more reliable

2/ install a non-rcd protected circuit for your computer equipment, or protect it with something like a 100mA RCD - I prefer no RCDs at all, but there are constraints on cable runs using this method, and no socket should be anywhere likely to be used for plugging in your lawn mower, or other portable equipment to be used outdoors.  The later point can be overcome by using RCD protected sockets. (you could also take circuit off RCD and use RCD sockets depending on cable runs).

How many RCD's does your existing fuseboard have? 

Is there 1 "up front" ?

Is there 2 protecting the socket circuits ?

Are there 2?

And what make is the fuseboard?

Leonard Powers said:

Hi there,

Firstly, I'm not an electrician but an end user.  I've struggled to figure out this problem I have and struggled even more to find an electrician who is willing to even look at the problem when I explain what is happening.

I work mainly from home and have a lot of computer equipment running in the house.  The problem I have is when I power on the server equipment I need for work, the main RCD in the fuse box trips out.  I've managed to get it working to a point that I can power on a single server with just a single power cable installed.  If I plug in the 2nd power cable (they have dual power supplies), the RCD will trip.

My colleague who does the same job has similar equipment in his house.  He had exactly the same problem and we discovered from a website that it has something to do with computer equipment (servers, desktops, laptops) etc all having mini circuit breakers built into them.  Apparently, they make the line very sensitive. (forgive me if what I'm saying is all rubbish - total newbie here).

My colleague fixed his problem by having a new circuit installed with a separate fuse box next to his main one.  This was quite easy to do since everything was in his garage.  Mine is in my utility room so more difficult?

I'm hoping this sound familiar to someone.  I've had one quote from an electrician who never got back to me.  He suggested running all new power to the garage (would prefer the kit to run in there) and that was looking at costing around £1200.  Another electrician said to put in a new fuse box with RCBOs?

Any suggestions on what I can do?  And if anyone is near Milton Keynes, I'm still looking for an electrician to look at this problem.

Click to expand...

Welcome to the forum, A bit of background detail may help you make your decision.  An RCD is a safety device designed to protect against electrical shock. It measures any current leaking from the circuit. It must NOT operate at 15miliamps or less, but MUST operate at 30miliamps or greater as that is sufficient to kill a healthy adult. (That is 0.03Amps, remember your socket circuit could allow over 1000 times this amount of electricity to flow through it in normal use if it is rated at 32Amps). So we are talking exceptionally small amount of electricity leaking, but some appliances also have natural leakage, especially computer equipment. So if you have multiple appliances with sufficient natural leakage then they can trip an RCD. Or an RCD may be over sensitive and tripping too early. Wiring regulations do say that installations must be designed to minimise inconvenience in the event of a single fault  (Reg 314). I would suggest that either your RCD is oversensitive or your installation has insufficient RCD's per the quantity of final circuits. Probably the latter, it is easy for someone with an appropriate tester to verify if you RCD is operating correctly, probably just a standard 1hour call out charge. In an ideal world every circuit would have its own RCBO, but they are more expensive than standard MCB fuses which is why a lot of electricians & customers opt for the cheaper, but potentially far more inconvenient option. An individual RCD board may well solve your problem as you can get similar issues with some makes of electric ovens/cookers as they can have natural leakage, also old fluorescent tube fittings, so the more potential leaky appliances you have sharing a single RCD, the greater the risk of inconvenience.  

Doc H.