Electrical wiring queries (2...so far!)
 

Do these sound right & proper?

a) 2 X 16A immersion heaters in a heatbank

Both on one circuit on a 32A MCB, on a new 2X RCD split CU.
Seperately switched, in two locations viz:-
1) next to heatbank via 2 X switched fused spurs (?) with a 13A (plug
type) fuse in each
2) in neighbouring room via 2 X 45a DP switches (more convenient for
residents to control)

Queries
13A fuses for 16A immersions?
45A DP switches - wouldn’t 20A DP do and be a bit cheaper?


b) Is it a requirement (or worth doing) to cover cables on walls with
plastic capping prior to dot’n’dab plasterboarding and skimming? If
it’s been installed is there any way of checking apart from
destructive investigations?

cheers

JimK

Electrical wiring queries (2...so far!)
 

"jim" wrote in message
...
Do these sound right & proper?

a) 2 X 16A immersion heaters in a heatbank

Both on one circuit on a 32A MCB, on a new 2X RCD split CU.
Seperately switched, in two locations viz:-
1) next to heatbank via 2 X switched fused spurs (?) with a 13A (plug
type) fuse in each
2) in neighbouring room via 2 X 45a DP switches (more convenient for
residents to control)

Queries
13A fuses for 16A immersions?
45A DP switches - wouldn’t 20A DP do and be a bit cheaper?


b) Is it a requirement (or worth doing) to cover cables on walls with
plastic capping prior to dot’n’dab plasterboarding and skimming? If
it’s been installed is there any way of checking apart from
destructive investigations?


I would expect two 16A MCBs and two 20A DP switches.

There is no requirement for capping.

Adam

Electrical wiring queries (2...so far!)
 

ARWadsworth wrote :
Queries
13A fuses for 16A immersions?
45A DP switches - wouldnt 20A DP do and be a bit cheaper?

The 13amp fuses might well last for months, but none the less they are
not appropriate, nor is the spur unit rated at 16amp.

Two separate circuits from the DB would be a better way to it, each
rated at 16 or 20amp. Failing that, a 2way DB mounted at the far end of
the 32amp feed, with a 20amp rated DP switch for control.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Electrical wiring queries (2...so far!)
 

In article
,
jim wrote:
13A fuses for 16A immersions?

Are they actually 16 amp? Common ones are 3kW so 13 amp fusing is fine.
But are normally fed with a 16 amp radial circuit from the CU as that's
the closest MCB - and the circuit will be protected ok by that.

45A DP switches - wouldn’t 20A DP do and be a bit cheaper?

Indeed. Perhaps they had a job lot. ;-)

--
*How about "never"? Is "never" good for you?

Dave Plowman London SW
To e-mail, change noise into sound.

Electrical wiring queries (2...so far!)
 

"Harry Bloomfield" wrote in message
k...
ARWadsworth wrote :
Queries
13A fuses for 16A immersions?
45A DP switches - wouldnt 20A DP do and be a bit cheaper?

The 13amp fuses might well last for months, but none the less they are not
appropriate, nor is the spur unit rated at 16amp.

Two separate circuits from the DB would be a better way to it, each rated
at 16 or 20amp. Failing that, a 2way DB mounted at the far end of the
32amp feed, with a 20amp rated DP switch for control.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk


The OP will have to have a look and see what the "one circuit" that feeds
the heaters consists of. I do like the idea of a 2 way CU at the far end of
the circuit if it is a 4mm or 6mm supply.

Adam

Electrical wiring queries (2...so far!)
 

On 30 Aug, 10:55, "ARWadsworth"
wrote:
"Harry Bloomfield" wrote in message

k...



ARWadsworth wrote :
Queries
13A fuses for 16A immersions?
45A DP switches - wouldn’t 20A DP do and be a bit cheaper?

The 13amp fuses might well last for months, but none the less they are not
appropriate, nor is the spur unit rated at 16amp.

Two separate circuits from the DB would be a better way to it, each rated
at 16 or 20amp. Failing that, a 2way DB mounted at the far end of the
32amp feed, with a 20amp rated DP switch for control.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

The OP will have to have a look and see what the "one circuit" that feeds
the heaters consists of. I do like the idea of a 2 way CU at the far end of
the circuit if it is a 4mm or 6mm supply.

Adam

yep I'll have a look later on and come back with full spec.
cheers
JimK

Electrical wiring queries (2...so far!)
 

On 30 Aug, 11:00, jim wrote:
On 30 Aug, 10:55, "ARWadsworth"
wrote:



"Harry Bloomfield" wrote in message

. uk...

ARWadsworth wrote :
Queries
13A fuses for 16A immersions?
45A DP switches - wouldn’t 20A DP do and be a bit cheaper?

The 13amp fuses might well last for months, but none the less they are not
appropriate, nor is the spur unit rated at 16amp.

Two separate circuits from the DB would be a better way to it, each rated
at 16 or 20amp. Failing that, a 2way DB mounted at the far end of the
32amp feed, with a 20amp rated DP switch for control.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

The OP will have to have a look and see what the "one circuit" that feeds
the heaters consists of. I do like the idea of a 2 way CU at the far end of
the circuit if it is a 4mm or 6mm supply.

Adam

yep I'll have a look later on and come back with full spec.
cheers
JimK

ok had a look now and there is

both wired to 1way in the CU (tho outside of the RCDs so presumably
it's a 32A RCBO? - has a yellow test button)
from CU in 2 runs of 4.0mm T+E to the 45A DP switches,
from 45A switches in 2 runs of 4.0mm T+E to the 13A switched fused
spurs next to the heatbank
from the 13 A spurs in heat resistant 3 core flex to each immersion

yes the immersions are 3kw each (the install notes required 16A
supplies for each which was where I got the 16A idea from...)

JimK

Electrical wiring queries (2...so far!)
 

"John Rumm" wrote in message
o.uk...
jim wrote:
On 30 Aug, 11:00, jim wrote:
On 30 Aug, 10:55, "ARWadsworth"
wrote:



"Harry Bloomfield" wrote in message
k...
ARWadsworth wrote :
Queries
13A fuses for 16A immersions?
45A DP switches - wouldn’t 20A DP do and be a bit cheaper?
The 13amp fuses might well last for months, but none the less they are
not
appropriate, nor is the spur unit rated at 16amp.
Two separate circuits from the DB would be a better way to it, each
rated
at 16 or 20amp. Failing that, a 2way DB mounted at the far end of the
32amp feed, with a 20amp rated DP switch for control.
--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk
The OP will have to have a look and see what the "one circuit" that
feeds
the heaters consists of. I do like the idea of a 2 way CU at the far
end of
the circuit if it is a 4mm or 6mm supply.
Adam
yep I'll have a look later on and come back with full spec.
cheers
JimK

ok had a look now and there is

both wired to 1way in the CU (tho outside of the RCDs so presumably
it's a 32A RCBO? - has a yellow test button)
from CU in 2 runs of 4.0mm T+E to the 45A DP switches,
from 45A switches in 2 runs of 4.0mm T+E to the 13A switched fused
spurs next to the heatbank
from the 13 A spurs in heat resistant 3 core flex to each immersion

yes the immersions are 3kw each (the install notes required 16A
supplies for each which was where I got the 16A idea from...)

In which case that all seems to be in order then ;-)

--
Cheers,

John.


It is just an odd setup. I cannot find anything dangerous about the setup it
just seems odd or just overkill. The sparks may not have had the specs about
the heaters. He certainly did not lay 4mm T&E for fun.

The standard circuit would be two seperate 16A MCBs using 2.5 T&E and 20A
double pole switches in all rooms.

As John says, "it is in order"

Adam

Electrical wiring queries (2...so far!)
 

On 30 Aug, 15:58, "ARWadsworth"
wrote:
"John Rumm" wrote in message

o.uk...



jim wrote:
On 30 Aug, 11:00, jim wrote:
On 30 Aug, 10:55, "ARWadsworth"
wrote:

"Harry Bloomfield" wrote in message
. co.uk...
ARWadsworth wrote :
Queries
13A fuses for 16A immersions?
45A DP switches - wouldn’t 20A DP do and be a bit cheaper?
The 13amp fuses might well last for months, but none the less they are
not
appropriate, nor is the spur unit rated at 16amp.
Two separate circuits from the DB would be a better way to it, each
rated
at 16 or 20amp. Failing that, a 2way DB mounted at the far end of the
32amp feed, with a 20amp rated DP switch for control.
--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk
The OP will have to have a look and see what the "one circuit" that
feeds
the heaters consists of. I do like the idea of a 2 way CU at the far
end of
the circuit if it is a 4mm or 6mm supply.
Adam
yep I'll have a look later on and come back with full spec.
cheers
JimK

ok had a look now and there is

both wired to 1way in the CU (tho outside of the RCDs so presumably
it's a 32A RCBO? - has a yellow test button)
from CU in 2 runs of 4.0mm T+E to the 45A DP switches,
from 45A switches in 2 runs of 4.0mm T+E to the 13A switched fused
spurs next to the heatbank
from the 13 A spurs in heat resistant 3 core flex to each immersion

yes the immersions are 3kw each (the install notes required 16A
supplies for each which was where I got the 16A idea from...)

In which case that all seems to be in order then ;-)

--
Cheers,

John.

It is just an odd setup. I cannot find anything dangerous about the setup it
just seems odd or just overkill. The sparks may not have had the specs about
the heaters. He certainly did not lay 4mm T&E for fun.

The standard circuit would be two seperate 16A MCBs using 2.5 T&E and 20A
double pole switches in all rooms.

As John says, "it is in order"

Adam

As I recall the heatbank was there when they wired it up (so heaters
specs etc were freely on view to them)..
The 12 way CU is very full though perhaps that may be why - to leave a
couple of spare ways?

JimK

Electrical wiring queries (2...so far!)
 

jim coughed up some electrons that declared:


As I recall the heatbank was there when they wired it up (so heaters
specs etc were freely on view to them)..
The 12 way CU is very full though perhaps that may be why - to leave a
couple of spare ways?

JimK

It's not illogical.

For my heatbank, I've allowed a single 45A RCBO in the main CU.

That will feed a local set of MCBs at the heatbank cupboard, 3 x 16A for the
3 immersion heaters and 1x 6A for the control circuits and boiler.

It made more sense than 4 x RCBOs or 1 x RCD + 4 x MCBs in the main CU
(which is large and still fairly full).

It also makes sense (to me at least) to be able to throw the 45A RCBO and
know that the entire heating system is dead.

It also allows me to house the 16A MCBs alongside contactors to operate the
immersion heaters from the main tank stat via a changeover switch where the
switch selects gas boiler or electrical backup driven by the same initial
control (tank stats and possibly a timer).

Cheers

Tim