Additional protection

[Waynem]

We have installed 230v bus bar track fitted in a floor void in an office block. These tracks supply the standard floor box outlets. The protective device is a standard BSEN 60898 MCB. I'm struggling to find out how this complies with the 17th edition regs. I was under the assumption that all sockets with a rating of up to 20A had to have additional protection. Any ideas?

 

[IQ Electrical]

I could make a case for compliance where the installation is used by employees and is (as required by the electricity at Work Regulations 1989) under the control of a skilled or instructed person.

The exception here is sockets that can be used by members of the public, such as in an internet cafe to power the customer's own laptop etc. and (the main reason for the RCD requirement) socket outlets in a domestic situation.

The exception was introduced because installations under the Electricity at Work Regulations 1989 have to ensure that workplace equipment is safe and that systems are adequately maintained.

 

[Glen Stimson]

also being used for computers it possibly needs an high integrity CPC plus the earth leakage from them all could cause the RCD to nuisance trip if one was fitted.

 

[IQ Electrical]

also being used for computers it possibly needs an high integrity CPC plus the earth leakage from them all could cause the RCD to nuisance trip if one was fitted.

You might find that the busbar meets the requirements for high integrity earthing while the possibility of nuisance tripping is a design problem rather than an additional reason to omit the RCD protection.

 

[Waynem]

Thanks.
I did think that this may be the case. However, if you can't guarantee that the person is skilled or instructed surely the designer should err on the side of caution. There are cleaners that regularly plug into these floor boxes, Would these staff be classed as skilled or instructed? There are other design issues also. there appears to be nothing protecting the 2.5mm cable that connects the floor box to the bus bar track. With a 63A mcb poviding the only protection the possibilities for severe over load obvious. Think i'll be contacting the designer!

 

[malcolmsanford]

We install a lot of power track systems over here and all the track is protected by normal BS 60898 MCBs basically to
1 avoid RCD protection for the entire track
2. High protective conductor currents.

We normally fit BS 7288 RCD sockets on the majority of the tap off points, and normal sockets for larger ink jet printers, etc that are not normally portable.

Again Like IQ say it is regarded as it is an office/commericla enviroment that it is under the supervision of skilled or instructed persons

 

[IQ Electrical]

Thanks.
I did think that this may be the case. However, if you can't guarantee that the person is skilled or instructed surely the designer should err on the side of caution. There are cleaners that regularly plug into these floor boxes, Would these staff be classed as skilled or instructed? There are other design issues also. there appears to be nothing protecting the 2.5mm cable that connects the floor box to the bus bar track. With a 63A mcb poviding the only protection the possibilities for severe over load obvious. Think i'll be contacting the designer!

Normally provision would be made for 'cleaners sockets' which should be RCD protected due to the nature of use, as for the 2.5mm busbar feeds, a 63A device is certainly not acceptable.

 

[malcolmsanford]

Thanks.
I did think that this may be the case. However, if you can't guarantee that the person is skilled or instructed surely the designer should err on the side of caution. There are cleaners that regularly plug into these floor boxes, Would these staff be classed as skilled or instructed? There are other design issues also. there appears to be nothing protecting the 2.5mm cable that connects the floor box to the bus bar track. With a 63A mcb poviding the only protection the possibilities for severe over load obvious. Think i'll be contacting the designer!

Normally if your tap off point is under 3 mts then there is no need to protect the tap off cable, but then the track is normally rated at 32amp only.

If you have a 63amp track then you can normally only able to fit 63amp leads, which are normally colour coded, say grey for 32amp and green 63amp, and all the 63 amp taqp offs are fused. So chect that.