Electrical supplies used in domestic plumbing services

Domestic electrics-documents

British standard

Regulations

All of these documents will be used alongside manufacturers instructions.

18th edition

Voltages

Low voltage:

230v single phase AC
110v single phase AC

Extra low voltage for safety:

24v DC
18v DC
12v DC

Danger zone

A danger zone is within a bathroom, kitchen or outhouse. If an airing cupboard door is on the landing, that is not a danger zone, but if it is in the bathroom, it is a danger zone. If the boiler is in the loft, it is fine; in the kitchen it is not. To replace parts on these items in these locations, you need to be a Part P qualified plumber.

Under this regulation you do not, as a plumber, have to be Part P qualified to replace a like-for-like component, unless it is in a danger zone, when you need to be Part P registered.

Remember- for an installation you need to be a fully qualified electrician.

Electricity commonly used in plumbing situations

Here is a list where electricity is used in plumbing components and appliances;

Pumps
Showers
Programmers
Thermostats
Immersion heaters
Plugs/spurs
Boilers
Cookers

Tools

240v power drill

110v drill

All of these tools will be used regularly by a plumber in different circumstances, dependant on where you may be working and on which type of site.

Step down down transformer

Battery drill

Circuits

One way lighting circuit

House wiring for beginners

Ring main

Lighting circuit: Radial circuit

1.5mm twin and earth

6 amp circuit protection

One circuit upstairs and one downstairs

Ring main: Ring circuit

Sockets

2.5mm twin and earth

32 amp circuit protection (consumer unit)

13 amp appliance protection (plug)

Protection-

Fuses and MCBs are there to protect the circuit and appliance. If an appliance or circuit is overloaded, the insulation in the cable is the first item to get damaged and possibly burnt.

The fuse inside a fused spur will protect the cable and appliance.

Any visual faults need to be reported to the homeowner or your supervisor for them to make a decision.

All circuits and appliances must be protected by the use of a fuse or MCB. Modern regulations also require the use of an RCD
Every circuit and appliance must also have a means of isolation
Permanent de-commissioning is done at consumer unit
Temporary de-commissioning can be done at appliance.

MCB-miniature circuit breaker, for the protection of circuits.

Found in the consumer unit and protect one appliance or circuit
Trip out if an overload is detected.

Lighting 6 amp

Immersion 16 amp

Water heater 16 amp

Ring final 32 amp

Cooker 32A-45A (typically) amp

As plumbers, we are not allowed to interfere with either the ring final or lighting circuit.

Only a qualified electrician – competent person
We can attach an appliance from a fused spur.

Residual circuit breakers (RCD):

Found in modern consumer units
Trip out if there is an earth fault (test and re-set switch)
Plug-in RCDs should be used with 230v tools.

Consumer unit

Found where the electrics enter the property
Contains all MCBs, residual current device, RCDs and main isolator
Where the single source is divided into multiple circuits

Mains supply
Suppliers fuse
Meter
Consumer unit
Feeds the circuits

Earth bar

Up to the meter is the

responsibility of the supplier.

From the meter tails

onward is the responsibility

of homeowner.

Heating components

Central heating S plan

Wire in from switched fused spur:

• Programmer

• Cylinder thermostat

• Room thermostat

• Boiler

• Pump

• 2 x two port valves

Central heating Y plan

Wire in from switched fused spur:

• Programmer

• Cylinder thermostat

• Room thermostat

• Boiler

• Pump

• 1 x three port valve

Earthing

Correct earthing is very important, as the majority of electric shocks and electrocutions are due to incorrect earths or earthing faults
Any problems should always be reported to the customer.

Earthing to keep us safe from electric shocks: TNS from armoured cable

A TN-S system, shown in fig 1, has the neutral of the source of energy connected with earth at one point only, at or as near as is reasonably practicable to the source, and the consumer’s earthing terminal is typically connected to the metallic sheath or armour of the distributor’s service cable into the premises.

A TN-C-S system, shown here, has the supply neutral conductor of a distribution main connected with earth at source and at intervals along its run. This is usually referred to as protective multiple earthing (PME). With this arrangement the distributor’s neutral conductor is also used to return earth fault currents arising in the consumer’s installation safely to the source. To achieve this, the distributor will provide a consumer’s earthing terminal whi

A TT system, shown above, has the neutral of the source of energy connected as for TN-S, but no facility is provided by the distributor for the consumer’s earthing. With TT, the consumer must provide their own connection to earth, i.e. by installing a suitable earth electrode local to the installation.

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