The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Consumer unit feed / main tails more than 3m

Hi, what are the requirements when a consumer unit is to be located where the mains tails are more than 3m from the cut-out? Quickly searching online it seems that a switched fuse unit (60A, 80A, 100A as applicable) is required after the meter? Does anyone know the regulation number in BS7671? Some have mentioned taking high voltage drop and Ze into consideration for a long run. Is SWA usually used? It is safer and could be buried in a wall if needed couldn't it? Mains tails are a bit dodgy anyway as contacting the line you could get the full PFC so I prefer the idea of the earthed armouring. 25mm 3-core SWA at CEF is about £13 per meter. I guess that's what happens in blocks of flats?

In this installation, the current position of the intake and CU is in the kitchen. They would like it moving under the stairs if possible which would mean a 5 or 6 meter run from the kitchen, up above ceiling, across and down into the under-stairs cupboard. I could potentially take an alternative route behind the kitchen units. Thanks.

  • Slightly different tack a few miles down the road!

    I recall the Irish using a DIN rail mounted HBC fuse as their incoming device some years ago - the switch to a DP MCB puzzles me - isn't there likely to be a complete lack of discrimination with downstream MCBs/RCBOs on faults?

       - Andy.

  • Indeed AJ, this has been much discussed here but there doesn’t seem to be a problem. Perhaps the convenience of a device that can be reset is the overriding factor.