Fused Spur Requirements

[installer44]

Have been on a course for installing fused spurs to get me up to spec, however there are still a few questions where I cant seem to det a definate answer.---

If one or both of the bondings is missing for gas/water can the spur still be installed with the point added to the depatures from regs section of the MWC? (obviousley the main earth reading would be tested as ok)

Can we wire in to the old style consumer units that have the wire fuses, not starting a new cct though?

[DirectFS]

Have been on a course for installing fused spurs to get me up to spec, however there are still a few questions where I cant seem to det a definate answer.---

If one or both of the bondings is missing for gas/water can the spur still be installed with the point added to the depatures from regs section of the MWC? (obviousley the main earth reading would be tested as ok)

Can we wire in to the old style consumer units that have the wire fuses, not starting a new cct though?

If supplementary bonding is missing, the installation is in any case non compliant. You would note on your inspection form that there was a serious defect, and the nature of the defect.

In practical terms, it wouldn't necessarily affect the installation of a plastic spur, as there are no extraneous metal parts - though installation of a metal cased end station would be a different matter. This would be doubly so, if in a special location, such as a bathroom, or in any case where installed near other exposed metal work, such as plumbing or central heating.

In the case of a metal panel or spur being used, e.g. contactable by a person, and also in reach of plumbing or heating I would suggest that a temporary (but properly attached) bond be made between the electrical connection to the spur/panel and the exposed metal in the area - not to do so leaves the user at risk to potential difference between the metal surfaces, and hence, shock. You alternative is not to power the system up, ensuring also no live connection to the system.

To answer your second point, I don't believe wire fuses comply with disconnection times indicated in 17th edition - so, you would be unable to use wire fuses as your means of circuit protection and remain complaint. However, if you're working within a system which has wire fises as the main form of protection, then clearly the system is not 17th edition in any case - though your work should be certificated to that standard.

IMO, it is never good practice to spur directly from a fuse or MCB, as this leads to confusion, and in your case would probably introduce mixed colours in an environment where none so far exist. My own preference would be either to add, or have added, another compliant board, and dedicate a circuit on that to the alarm. This also has the advantage that you are not taking any responsibility for the existing system, though on the down side you are installing a new one.

Your alternative would be to spur from the appropriate circuit wiring in an appropriate junction box at a point after the protective fuse, and outside the fuse board.

Bill.

[installer44]

thanks for the good answers bill, just to comfirm is it ok to fit a spur on a system that has the old consumer units with the wired fuses?

[DirectFS]

thanks for the good answers bill, just to comfirm is it ok to fit a spur on a system that has the old consumer units with the wired fuses?

Yes, it is OK, and as long as the work you do - e.g. fitting the spur and connecting it to an existing circuit, does not extend to provision of a new circuit, then all you need to certificate is the work you've completed, do your readings, and comment on the apparent state of the system as far as you've disturbed it.

If you do connect it to an existing fuse way on a board, you will need to label the board as containing mixed colours, as undoubtedly, most of the wiring within will be the old red/black - and presumably, your spur will be run in the brown/blue harmonised colours.

Bill.