Storage heaters, new 12 way board

[burntwire]

I need to replace a 12 way storage heater board and intend to us a 12 way dual rcd board, poss MK, RCBO's are too expensive, Whats peoples views on doing it this way ? or any problems I might encounter ?

 

[flameport]

First - do these heaters really need RCDs? Lots of heating elements on an RCD is likely to cause problems in the future.

Second - 12 heaters on one board is a lot - what is the total loading? No diversity allowed with storage heaters.
Even if an average of 2kW each, this is still over 100A, which is too much for a standard board.

 

[Steve]

If you use a dual RCD board, make sure theres an even split, and you dont just do upstairs on one side and downstairs on the other.

 

[burntwire]

Hi,

The reason I was going to use RCD was because of the cable installation method - chased in wall etc etc

I shall work out the total load in a bit but afaik 1 way is unused and 1 is water element

The property is undergoing a full restoration however it is an old stone cottage

 

[RF Lighting]

Tripetty tripetty trip trip trip

 

[burntwire]

Ive just worked out the rating @ 22990 kw in total (existing units) not including the immersion heater, Ive decieded to use RCBO's now to limit any tripping issues, I will have to talk to the householders to see how I can reduce the amount of heaters, there are actually 13 heaters in total.

 

[rebuke]

You also need to check what their incoming supply is rated to - most domestic properties have a maximum of 100A SP, which leaves nothing left for anything other than the storage heaters when they're on - if they run the immersion heater as well, after a short period of time the cut-out fuse will almost certainly blow...

Edit to add that it will almost certainly cost them a fortune as well, even at economoy 7 pricing etc!

 

[Steve]

And the contacts on whatever brings it all online at eco7 time, will probably wear out very quickly.

 

[Pensdown]

Ive just worked out the rating @ 22990 kw in total

You might want to check your calculations......22,990kW?

 

[rebuke]

I'm assuming that must be a typo, and he meant either 22.99kW, or 22990W - if it's nearly 23MW then somethings really wrong, and you'll need a small power station to run it!

 

[crystal ball]

Tripetty tripetty trip trip trip

Mmm but will it trip, I used to think that would happen until someone pointed out a vital fact

 

[ban-all-sheds]

Footage shot earlier of a house with 23MW of heating.....

 

[flameport]

Mmm but will it trip, I used to think that would happen until someone pointed out a vital fact

The fact being that the element casings are not usually connected to the circuit earth?

Regardless, it is poor design to have a whole lot of storage heaters on RCDs, particularly considering any trip will not be noticed until the following day, when the house is completely cold and there is no way of heating it.

 

[burntwire]

Surely RCBO'S will be ok, They are there to protect the cable, not the heater and each RCBO will be rated at suitable amps,

I did mean watts not kw, as im sure you all knew really !!

Thats a good video clip not far off what really happened to the property altough not down to the electrics.

This place has storage heaters everywhere even 100mm from the bath, Will be changing them to towel rails and looking at other ways to reduce load, this is quite tricky because of need to maintaain heat levels .Other option would be gas(stored) or oil heating but its not down to me.

 

[ban-all-sheds]

100mm from the bath.

That's not on.