No, not a 70’s energy saving idea from the gas board, but instead a way to squeeze multiple electric showers into a property without blowing the maximum demand figure (or the incoming fuse).


I came across a copy of the Daily Mirror from January 1974 recently. My grandparents had bought it around the date I was born and saved it with some other publications so I could look back at what was happening in the world at the time that I made my grand entrance.

Back then the UK was gripped in an energy crisis and so the South Eastern Gas Board ran a competition with a £10 prize to see if people could come up with simple energy saving ideas.

The winner was Ida Jones who had the idea to share a bath, something which caused some rather eyebrow raising controversy at the time with conservative society being horrified at the Carry-On style titillation the idea churned up in the press.

My 1974 Daily Mirror has it ‘splashed’ over the centre pages complete with seaside-postcard humour cartoon, comments from celebs and a random vicar (who was all for it), and tips on the etiquette of mixed bathing. Tip number ten reads ‘The gentleman, when the bath is over, helps the lady step out onto the nice dry bath-mat, and helps rub her dry with the towel. The lady, unfortunately, is left to clean the bath’.

showershare

Ida also had the idea of only boiling as much water as was needed when using a kettle instead of filling it to the top, however that top tip which is still touted today seems to have generated fewer ripples of controversy.

These days the suggestion of sharing a bath wouldn’t cause such a stir, and besides, most people prefer a shower.

Showers are really designed for quick cleaning, however many of us are guilty of prolonged naked singing sessions under jets of warm water while pretending the soap-on-a-rope is actually a microphone. Unfortunately doing such is probably going to add a significant chunk to your energy bill and would have poor Ida wondering if her message of efficient bathing helped do anything to ease energy consumption in the long term!

The three most common types of shower are:

1. Non-electric (gravity) shower which often comes off the bath taps and simply uses hot water from a tank located above.

2. The electric pump shower which pumps the hot water from the tank instead of using gravity. You’d see this where the tank is located on the same level or below the shower.

3. The fully electric shower which simply has a cold water feed and heats the water as it passes through the appliance.

This third type is very popular because it requires less plumbing to install with just a cold feed and no separate hot water pipe back to a tank. It can heat water instantaneously for as long as you want so there’s no need to wait for the hot water tank to get up to temperature and no cutting the shower short when the tank is empty.

However were you aware that if you have this type of electric shower it is likely to be the most energy slurping appliance in your home? Heating cold water to about 35-41 degrees as it rushes past under pressure requires quite some juice. A 7.5kW shower will consume up to 32A, 8.5kW up to 37A, 9.5kW up to 42A and a 10.5kW rated unit up to 46A. A quick look at your consumer unit will likely identify the shower circuit has having the biggest (highest rated) fuse or circuit breaker, more than an electric hob, oven, socket or heating circuit.

IMG-20130809-00527

A typical installation showing the shower as the highest rated breaker, 40A in this case


When fitting an electric shower you have to be mindful of the maximum demand of your property, that is to say the total current draw which is likely, based on the particulars of the fixed installation. The maximum demand cannot be allowed to exceed the rated current of the service head fuse. If you have a maximum demand of 100A but a 60A service head fuse then you risk cooking that fuse with obvious consequences.

If your property does only has a 60A fuse in the service head, then losing 40 or so Amps whenever the shower is in use doesn’t leave much margin for everything else. With dad hogging the shower on a cold winter morning while the rest of the family is using the toaster, kettle, lighting, a hair dryer etc. there is the potential for the incoming fuse to be overloaded leaving everyone in the dark.

Normally a single shower isn’t really a problem and most people sensibly stick with the lower power models (7.5 or 8.5kW), however en-suites with shower cubicles seem to be becoming more popular and it’s not unusual to see multiple electric showers being fitted into a single home.

In order to negate the risk of overloading your main fuse, it is perhaps wise to consider a ‘priority controller’. This device allows two showers to hang off one fuseway, but will only allow one of those showers to operate at any one time.

As soon as one shower starts pulling down a load above about 10A, a contactor cuts the feed to the second shower. These things can either operate on a first-come-first-served basis or you can choose a model which prioritises one shower over the other so, for example, the shower in the main bathroom could always be operated by automatically killing one that may be in use in an en-suite.

Because it’s not possible to run both showers simultaneously, the maximum demand is the same as if a single shower is installed.

IMG-20130805-00511

Here's one I fitted earlier. This Garo priority controller allows two new en-suites
in an extension build to each have a shower running off a single breaker at the consumer unit


These things are particularly popular in Ireland where service head fuses are generally 63A. In the UK domestic installations tend to range from 60A to 125A with 80A to 100A being the most common. This means a priority controller is rare here, but if you have a larger property or you’re fitting multiple en-suites, or if converting a house into student accommodation/installing a granny flat, etc. then it’s worth considering. This is especially the case if your sparkie/plumber has already told you that installing extra showers isn’t possible because of the limitations of the electrical installation or if they’ve gone ahead and installed such without consideration for maximum demand and your service head fuse has been fried once or twice already.

If you’d like to speak to me about such an installation, please get into contact for a chat.