Where to mount switch for hand wash unit (in the UK) ?

[Dave]

My garage has a small room attached with a sink. I'd like to fit a hand
wash unit above the sink, so I can get hot water. The one I have is
similar to this:

http://www.plumbnation.co.uk/site/heatrae-sadia-handy-3---7-hand-wash-units/

but is 7.2 kW.

I consider myself competent to fit the water heater (I have an
electrical engineering degree, I'm a member of the IEE and a chartered
engineer). However, I'm not sure of the IEE regulations on this, in
particular where a switch must be placed.

The house has a 3-phase supply, one of which goes to the garage. This is
fused at 80A in the house, and goes to an 8-way consumer unit in the
garage. Hence there is plenty of power in the garage for this.

I have fitted a 40 A RCBO, with a trip current of 30 mA. (The load
current is 32 A @ 230 V, so I thought a 40 A breaker was probably optimal).

Obviously I need to run a cable from the consumer unit to hand wash
unit. For this I have 6 mm^2 twin and earth.

But I have two questions:

1) Is it normal (or advisable) to put a switch close to the hand wash
unit, so it can be isolated without going to the consumer unit? Given
the heater will be on its own RCBO I could switch it off at the consumer
unit, without affecting anything else. It's only about 10 m away from
the consumer unit, but there is a door between the consumer unit and the
sink.

2) It if is usual to put a switch near the hand wash unit, where should
it be - height, distance from sink etc. Should it be so high up, that it
can't be reached from the floor without standing on something?

In some ways, I think it might be safer (and cheaper) to have no switch
near the handwash unit at all, but I suspect there should be one.

Can anyone tell me what the latest IEE regulations say on this?

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[Andrew Gabriel]

My garage has a small room attached with a sink. I'd like to fit a hand
wash unit above the sink, so I can get hot water. The one I have is
similar to this:

http://www.plumbnation.co.uk/site/heatrae-sadia-handy-3---7-hand-wash-units/

but is 7.2 kW.

I consider myself competent to fit the water heater (I have an
electrical engineering degree, I'm a member of the IEE and a chartered
engineer). However, I'm not sure of the IEE regulations on this, in
particular where a switch must be placed.

The house has a 3-phase supply, one of which goes to the garage. This is
fused at 80A in the house, and goes to an 8-way consumer unit in the
garage. Hence there is plenty of power in the garage for this.

I have fitted a 40 A RCBO, with a trip current of 30 mA. (The load
current is 32 A @ 230 V, so I thought a 40 A breaker was probably optimal).

Obviously I need to run a cable from the consumer unit to hand wash
unit. For this I have 6 mm^2 twin and earth.

That's OK providing it's not running in thermal insulation, and
not grouped with lots of other cables running at or near their
max capacity.

But I have two questions:

1) Is it normal (or advisable) to put a switch close to the hand wash
unit, so it can be isolated without going to the consumer unit? Given
the heater will be on its own RCBO I could switch it off at the consumer
unit, without affecting anything else. It's only about 10 m away from
the consumer unit, but there is a door between the consumer unit and the
sink.

A switch near enough to the heater to be under the direct control
of someone working on the heater is required (another room wouldn't
count). If the switch is too far away or in another room, it would
need to be of a type which can be locked in the off position by the
electrician's own padlock.

I would suggest using a pull-cord 40A electric shower switch.
Although a pull cord switch is not structly required in this
location, it's not unreasonable to think it might well be used
by people with wet hands, having just washed them, so it would
be a good idea here. Get a good quality one (such as MK) for
this high current load, not just the cheapest one in the store.
A pull-cord shower switch must have a mechanical on/off indication
(and it might also have a neon light, but that's not required).

I suggest you mount it so the cord can be reached from the basin,
but it doesn't hang down in the way directly over the basin or
heater.

2) It if is usual to put a switch near the hand wash unit, where should
it be - height, distance from sink etc. Should it be so high up, that it
can't be reached from the floor without standing on something?

In some ways, I think it might be safer (and cheaper) to have no switch
near the handwash unit at all, but I suspect there should be one.

That's why I suggest using a pull-cord shower switch, which will
be fixed to the ceiling.

Can anyone tell me what the latest IEE regulations say on this?

17th Edition regs will apply.

 

[Dave]

That's OK providing it's not running in thermal insulation, and
not grouped with lots of other cables running at or near their
max capacity.

That is not a problem.

A switch near enough to the heater to be under the direct control
of someone working on the heater is required (another room wouldn't
count). If the switch is too far away or in another room, it would
need to be of a type which can be locked in the off position by the
electrician's own padlock.

That is the sort of help I needed. The consumer unit (MK Sentry) can't
be padlocked, so I need a switch. (At least I don't think it can be
padlocked. I can't say I noticed, but it might be possible to do it).

I would suggest using a pull-cord 40A electric shower switch.
Although a pull cord switch is not structly required in this
location, it's not unreasonable to think it might well be used
by people with wet hands, having just washed them, so it would
be a good idea here. Get a good quality one (such as MK) for
this high current load, not just the cheapest one in the store.
A pull-cord shower switch must have a mechanical on/off indication
(and it might also have a neon light, but that's not required).

I suggest you mount it so the cord can be reached from the basin,
but it doesn't hang down in the way directly over the basin or
heater.

Good idea. The unit has its own 'switch', which is controlled by the
flow of water. i.e. turn water on, and the heater runs. But clearly that
is useless for servicing. I don't believe there is any other switch on
it, but I'm not 100% sure. (It is in the garage and I can't be bothered
to go and look).

That's why I suggest using a pull-cord shower switch, which will
be fixed to the ceiling.

I'll get one of them.

17th Edition regs will apply.

I was aware of that, but I don't have a copy of the regs, and don't want
to buy a copy just to find this out where to mount a switch. But your
idea of a shower type switch seems good.

Dave


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'Exchange Experts' take questions posted on the web and try to find
idiots stupid enough to pay for the answers, which were posted freely
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[Andrew Gabriel]

That is the sort of help I needed. The consumer unit (MK Sentry) can't
be padlocked, so I need a switch. (At least I don't think it can be
padlocked. I can't say I noticed, but it might be possible to do it).

I think most (all?) MK MCB's can actually be locked off.
You will see two tiny holes either side of the dolly,
and they take a locking bracket. Can also be used to lock
the MCB's on (that doesn't stop them from tripping, but
does stop them from being switched back on again after
having tripped).

However, the local pull-cord switch is a much better solution,
and I would also suggest you switch off there when you've
finished working in the garage for the day.

I'll get one of them.

One other thing -- you tug quite hard on the cord of those
high current switches -- make it's screwed into a joist and
not just plasterboard.

I was aware of that, but I don't have a copy of the regs, and don't want
to buy a copy just to find this out where to mount a switch. But your
idea of a shower type switch seems good.

IEE also do something called the "On-Site Guide". That is a
very good summary of the parts of the regs applicable to a
house. Make sure you buy the one which goes with the 17th
Edition (still lots of older ones in the shops).

When modifying an installation like this, you should also
check things like the installation's earth bonding are up to
current regs. You don't need to bring the whole installation
up to 17th edition regs, but the parts relevant to the safety
of your new work should be.

 

[Dave]

I think most (all?) MK MCB's can actually be locked off.
You will see two tiny holes either side of the dolly,
and they take a locking bracket. Can also be used to lock
the MCB's on (that doesn't stop them from tripping, but
does stop them from being switched back on again after
having tripped).

Thanks for that. I'll check for interest sake, but from a practical
point at home, I'm not going to padlock them. I'll just fit the pull switch.

However, the local pull-cord switch is a much better solution,
and I would also suggest you switch off there when you've
finished working in the garage for the day.



One other thing -- you tug quite hard on the cord of those
high current switches -- make it's screwed into a joist and
not just plasterboard.

Cheers. Useful to know. I can easily arrange that. All I need now is the
weather to get a bit warmer. I don't fancy fitting this in this weather
- I'll wait until the weather warms up and I don't need it!

There is one there are the minute, but it is only 2 or 3 kW, and just
not enough to be very useful when the outside temperature is low.

IEE also do something called the "On-Site Guide". That is a
very good summary of the parts of the regs applicable to a
house. Make sure you buy the one which goes with the 17th
Edition (still lots of older ones in the shops).

Thanks.


PS, I will probably see you in a few days. There is someone of your name
giving a talk at LOSUG on ZFS, which I assume is probably you.

Dave (using a Sun Blade 2000 with ZFS file systems)


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I respectfully request that this message is not archived by companies as
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'Exchange Experts' take questions posted on the web and try to find
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[Andrew Gabriel]

PS, I will probably see you in a few days. There is someone of your name
giving a talk at LOSUG on ZFS, which I assume is probably you.

Yes, that's me!

Dave (using a Sun Blade 2000 with ZFS file systems)

See you.