Consumer Unit Discrimination ?

[dave (retired)]

I have just seen a recently replaced consumer unit in a sports pavilion, it has RCD as mainswitch, 4 RCD's so there is no discrimination between circuits, can someone please confirm I am right in saying this does not comply with regs., it only wants a minor fault on say a kettle and all lights go out, this would be dangerous, elderly and children use this building. Your help will help me to convince the building owners it is wrong.

Thanks Dave.

 

[Sharpend]

Is the upfront rcd a time delay version? Your say 4 RCDs is that rcbo's or mistaken MCB's?

 

[NozSpark]

Do you mean it has a RCD main switch and 4 MCBs?

If so then its not the best setup, but there must be hundreds of thousands of CUs that have the same configuration.

The best setup would have a isolator main switch and RCBOs..... all at a height that that is easily accessible by the occupants,,, but you have to balance all this with the associated cost

 

[Doc Hudson]

As RCD's come in different ratings and types, and you have not given any detail, nor have you stated what the earthing arrangement is, then it is hard to say if there is actually anything wrong. Might I hazard a guess that it could be a TT installation with 100ma time delayed front end, with multiple 30ma RCD protecting individual groups of circuits to minimise inconvenience? more info or a photo please.

Doc H.

 

[Apache]

This consumer unit discrimination is serious. They are all white these days. You used to see a few old black Wylex ones but no longer. I haven't seen a black, brown or yellow one for sale for years.............

 

[batty]

If its not TT surely most circuits would not need RCD protection. More information is required.

 

[dave (retired)]

Sorry, made a mistake in post, it should have read, RCD mainswitch and four MCB's, it is TN-C-S, RCD is 30 m/a . I feel normal mainswitch and four RCBO,s would give the best protection. Thanks for your replies so far, it will help me get my suggestions across to the owners of the building.

Dave.

 

[batty]

Does it actually need RCD protection on all circuits then if its commercial?

 

[Doc Hudson]

You are correct that better protection would be provided by 4 RCBO's, however if the installation is only four circuits then the costs of 1x RCD -vs- 4x RCBO may have been an issue when the board was replaced. Is this sports pavilion some sort of community building where funding and resources are limited? The regulations only require you to minimise inconvenience in the event of a single fault. They do not say that you cannot have a single RCD if you so wish. The hazard or danger you refer to about lights going off, would also be true in the event of a power cut whilst the building was in use. Therefore suitable emergency lights would overcome both the power cut and your loss of light if the RCD trips problem. 

Doc H.

 

[SBS Dave]

Hi Dave,

If the existing DB has a standard DIN rail, then the RCD and MCBs could be replaced by a Main Switch + 4 x RCBOs, as you and others suggest, using the existing box.

If there is sufficient height for Standard RCBOs in the box, then I can supply Main Switch + 4 x RCBOs for £58.00 inc postage + VAT.

If space is tight, I can do the Main Switch + 4 x Compact RCBOs inc busbars, for £65.00 inc postage + VAT.

This will help you, when you speak to the owners.

SBS Dave